tag:blogger.com,1999:blog-49967695375010943842024-03-13T20:12:38.164+01:00Retos TerrícolasEarth Science Blog
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Blog sobre GeocienciaDaniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.comBlogger98125tag:blogger.com,1999:blog-4996769537501094384.post-6964480847988301612022-05-08T02:53:00.005+02:002022-11-04T19:06:15.561+01:00Tomanowos: la roca que sobrevivió al billar cósmico, a las megainundaciones glaciares y a la estupidez humana<div class="js-tweet-text-container" style="background-color: white;"><span style="font-size: x-small;">[This is the Spanish version of the english <a href="https://theconversation.com/tomanowos-the-meteorite-that-survived-mega-floods-and-human-folly-134213#:~:text=Tomanowos%20is%20a%2015%2Dton,their%20lives%20in%20supernovae%20explosions.">original in The Conversation</a>, Space.com, and Phys.org]</span></div><div class="js-tweet-text-container" style="background-color: white; font-size: 17.6px;">
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<tr><td><img alt="" border="0" data-aria-label-part="" src="https://pbs.twimg.com/media/CszofjOXYAEtQi6.jpg" style="background-color: transparent; background: transparent; border: 0px; box-shadow: rgba(0, 0, 0, 0.1) 0px 0px 0px; display: block; margin-left: auto; margin-right: auto; max-width: 100%; padding: 0px; position: relative; top: 0px; width: 506px;" title="Tomanowos" /></td></tr>
<tr><td class="tr-caption" style="font-size: 14.08px;"><span style="font-family: arial;"><span class="notranslate">Localización actual de Tomanowos en el Museo Americano de Historia Natural de Nueva York.</span> <span class="notranslate">Foto: DGC.</span></span></td></tr>
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<span style="font-family: arial;"><span class="notranslate">La roca más fascinante que conozco tiene un nombre milenario: </span><b style="font-style: italic;">Tomanowos.</b> Significa "<i>el visitante del cielo</i>" en el extinto idioma clacama. Según los miembros de la <a href="https://anthro.amnh.org/anthropology/databases/projects/nagpra20/grandronde.pdf">tribu norteamericana de los Clacamas</a>, Tomanowos vino para <i>unir el cielo, la tierra y el agua</i>.</span></div>
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<tr><td style="text-align: center;"><a href="https://3.bp.blogspot.com/-72AJGIiRoNs/V_PUWITyKRI/AAAAAAAAwlQ/xVCveethhccvBlFuENCrjqg3SIdnNpehgCLcB/s1600/NASA-SNR0519690-ChandraXRayObservatory-20150122.jpg" style="clear: right; color: #7c7c7c; margin-bottom: 1em; margin-left: auto; margin-right: auto; text-decoration-line: none;"><span style="font-family: arial;"><img border="0" height="320" src="https://3.bp.blogspot.com/-72AJGIiRoNs/V_PUWITyKRI/AAAAAAAAwlQ/xVCveethhccvBlFuENCrjqg3SIdnNpehgCLcB/s320/NASA-SNR0519690-ChandraXRayObservatory-20150122.jpg" style="background-color: transparent; background: transparent; border: none; box-shadow: rgba(0, 0, 0, 0.1) 0px 0px 0px; padding: 0px; position: relative;" width="320" /></span></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8px; text-align: center;"><span style="font-family: arial;"><span class="notranslate">Las explosiones de supernovas esparcen por el espacio</span><br />
<span class="notranslate">el hierro producido en las estrellas más pesadas.</span> <span class="notranslate">Este hierro </span><br />
<span class="notranslate">termina en nebulosas de partículas que terminan por formar</span><br />
<span class="notranslate">nuevas estrellas y protoplanetas como el que formó<br />Tomanowos.</span> <span class="notranslate">[Imagen: NASA]</span></span></td></tr>
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<span class="notranslate" face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white; font-size: 17.6px;">Hoy esta roca yace en el Museo de Historia Natural de Nueva York debido a</span><span class="notranslate" face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white; font-size: 17.6px;"> una de las historias más tronchantes que conozco en geología, acontecida cuando</span></span><span class="notranslate" style="background-color: white; font-family: arial; font-size: 17.6px;"> unos colonos se enteraron de su existencia </span><span class="notranslate" style="background-color: white; font-family: arial; font-size: 17.6px;">cerca de Portland (Oregón) </span><span style="background-color: white; font-family: arial; font-size: 17.6px;">hace un siglo</span><span class="notranslate" style="background-color: white; font-family: arial; font-size: 17.6px;">. </span></div><div class="js-tweet-text-container"><span style="font-family: arial;">
<span class="notranslate" face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white; font-size: 17.6px;"><br /></span>
<span class="notranslate" face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white; font-size: 17.6px;">Pero antes de entrar en eso, ¿qué sabemos sobre el orígen de esta roca?</span></span></div>
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<span style="font-family: arial; font-size: medium;"><span class="notranslate">Tomanowos es un meteorito de un tamaño inusual, compuesto por <span face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif"><span style="background-color: white;">15 toneladas de hierro y níquel (Fe 91%, Ni 7.6%).</span></span></span><span face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif"><span style="background-color: white;"> </span></span><span class="notranslate" face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white;">Como en otros meteoritos metálicos, sus átomos de <i>Fe</i> y <i>Ni</i> se <b>formaron en el núcleo de estrellas</b> que esparcieron por el espacio los subproductos de la fusión nuclear al terminar sus vidas en gigantescas explosiones de supernovas.</span><span face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif"><span style="background-color: white;"> Hace unos 4.500 millones de años, e</span></span><span class="notranslate"><span face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif"><span style="background-color: white;">stos átomos pululaban en una nebulosa de detritos cósmicos que comenzaba a agregarse en partículas de polvo, primero, y de rocas y protoplanetas después. </span></span></span>Esa nube formó nuestro Sistema Solar y Tomanowos fue parte del núcleo de uno de estos <b>protoplanetas</b> (los metales, más pesados que los silicatos, tienden a ocupar el centro de los planetas).</span></div>
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<span class="notranslate" style="font-family: arial;">Vesta, un protoplaneta superviviente del</span></div>
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<span style="font-family: arial;"><span class="notranslate">Sistema Solar primigenio.</span> La</span><span style="font-family: arial;"> gravedad forma</span></div><div style="font-size: 12.8px;"><span style="font-family: arial;">una estructura de capas </span><span class="notranslate" style="font-family: arial; font-size: 14.08px;"><span style="font-size: 12.8px;">ordenadas por</span></span><span class="notranslate" style="font-family: arial; font-size: 14.08px;"><span style="font-size: 12.8px;"> densidades </span></span></div><div style="font-size: 12.8px;"><span class="notranslate" style="font-family: arial; font-size: 14.08px;"><span style="font-size: 12.8px;">con elementos más pesados como </span></span><span class="notranslate" style="font-family: arial; font-size: 14.08px;">el hierro <span style="font-size: 12.8px;">concentrados </span></span></div><div style="font-size: 12.8px;"><span class="notranslate" style="font-family: arial; font-size: 14.08px;"><span style="font-size: 12.8px;">en el núcleo.</span></span><span style="font-family: arial; font-size: 14.08px;"> </span><span class="notranslate" style="font-family: arial; font-size: 14.08px;"><span style="font-size: 12.8px;">Tomanowos es un </span></span><span style="font-family: arial;">pieza</span><span style="font-family: arial; font-size: 14.08px;"> </span><span style="font-family: arial;">expulsada</span><span style="font-family: arial; font-size: 14.08px;"> </span><span style="font-family: arial;">del </span><span style="font-family: arial;">núcleo</span></div><div style="font-size: 12.8px;"><span style="font-family: arial;"> de un protoplaneta similar.</span></div><span style="font-family: arial;">
<span class="notranslate">[EPFL / Jamani Caillet, Harold Clenet]</span></span></td></tr>
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<span style="font-family: arial; font-size: medium;"><span class="notranslate" face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white;">También sabemos que, poco después, una <b>colisión</b> entre dos de esos protoplanetas devolvió nuestra pieza de museo a la soledad espacial. Lo sabemos<i> </i>porque es la única manera conocida de extraer una masa de 15 toneladas del </span><span class="notranslate">centro de un protoplaneta. Posteriores impactos <span face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif"><span style="background-color: white;">a lo largo de cuatro mil millones de años hicieron que la órbita del meteorito finalmente se cruzara con la de la Tierra. Eso ocurrió hace apenas 17.000 años.</span></span></span></span><div><span style="font-family: arial; font-size: medium;"><span class="notranslate" face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white;"><br /></span></span></div><div><span style="font-family: arial; font-size: medium;"><span class="notranslate" face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white;">Como resultado de este <b>billar cósmico</b>, el meteorito entró en nuestra atmósfera a una velocidad de unos 60.000 km/h, <b>aterrizando en el casquete glaciar que ocupaba el actual Canadá a finales del Pleistoceno</b>. Gracias a que el hielo es un lugar relativamente mullido para aterrizar, los glaciares son una importante fuente de meteoritos bien preservados. A estas alturas Tomanowos ya había atravesado un impresionante cúmulo de casualidades que le permitirían acabar en la sala del museo de Nueva York. Pero lo más increíble estaba todavía por ocurrirle.</span><br />
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<span style="font-family: arial;"><span class="notranslate">Durante las siguientes décadas, el hielo transportó lentamente a Tomanowos hacia el sur, hacia una lengua glaciar que en ese momento bloqueaba el río Fork en Montana (EEUU).</span> <span class="notranslate">Esa lengua glacial había bloqueado con hielo el valle del río acumulando una barrera de 600 m de altura que causó la formación aguas arriba de un enorme lago, hoy desaparecido pero estudiado por los sedimentólogos bajo el nombre de Lago Missoula.</span> Esto lo sabemos porque en los años 20, el doctor Joseph Pardee encontró abundantes sedimentos lacustres de un gran lago pleistoceno que carecía de una barrera física en su lado occidental. </span></div>
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<span style="font-family: arial;"><span class="notranslate">Arrastrado por el glaciar, Tomanowos llegó a esa gigantesca presa de hielo justo cuando</span></span><span style="font-family: arial;"><span class="notranslate"> esta colapsó desencadenando <b>una de las mayores inundaciones jamás documentadas. L</b>as <b>inundaciones de Missoula </b>(en plural porque el fenómeno se repitió decenas de veces) remodelaron el relieve de la inmensa región de los Scablands en el estado de Washington, un paisaje excavado por la erosión de este evento cataclísmico.</span> <span class="notranslate">Este fenómeno se conoce como <i>inundación </i></span></span><i style="font-family: arial;">glaciar</i><span style="font-family: arial;"> </span><span class="notranslate" style="font-family: arial;"><i>explosiva </i>y ocurre cada pocos años, por ejemplo, en el glaciar Perito Moreno (Argentina).</span><span style="font-family: arial;"> Sin embargo, e</span><span class="notranslate" style="font-family: arial;">l gran volumen de agua apresado en el Lago Missoula hizo que </span><span style="font-family: arial;">allí </span><span class="notranslate" style="font-family: arial;">el flujo de agua alcanzara el equivalente a <b>miles de Cataratas del Niágara</b>, concretamente unos 10 millones de metros cúbicos por segundo.</span><span style="font-family: arial;"> Para los curiosos, l</span><span class="notranslate" style="font-family: arial;">a investigación de estas inundaciones por Bretz y Pardee a principios del siglo XX condujo a uno de los </span><span style="font-family: arial;">más significativos </span><span style="font-family: arial;">cambios de paradigma en la geología: el reconocimiento de que los eventos catastróficos pueden contribuir significativamente a la evolución del relieve.</span></div>
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-pWd-BGxeamw/V_OvkEiZ-iI/AAAAAAAAwks/003iq4wosok0meOVSLtHA6DoD1VFCpjZwCLcB/s1600/floodsmap_lg.jpg" style="clear: right; color: #7c7c7c; margin-bottom: 1em; margin-left: auto; margin-right: auto; text-decoration-line: none;"><span style="font-family: arial;"><img border="0" height="199" src="https://1.bp.blogspot.com/-pWd-BGxeamw/V_OvkEiZ-iI/AAAAAAAAwks/003iq4wosok0meOVSLtHA6DoD1VFCpjZwCLcB/s320/floodsmap_lg.jpg" style="background-color: transparent; background: transparent; border: none; box-shadow: rgba(0, 0, 0, 0.1) 0px 0px 0px; padding: 0px; position: relative;" width="320" /></span></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8px; text-align: center;"><span style="font-family: arial;"><span class="notranslate">Mapa del recorrido de las inundaciones de Missoula, que <br />muestra el lago Missoula </span><span class="notranslate">(azul),</span> <span class="notranslate">la capa de hielo donde<br />aterrizó Tomanowos (al norte del </span><span class="notranslate">lago) y las áreas<br />inundadas de Washington y </span><span class="notranslate">Oregón (gris). </span><span class="notranslate">Fuente: Washington Univ.</span></span></td></tr>
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<span class="notranslate"><span face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif"><span style="background-color: white; font-size: 17.6px;">Al colapsar la presa glaciar, el meteorito, </span></span><b style="background-color: white; font-size: 17.6px;">atrapado en hielo</b> <span face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white; font-size: 17.6px;">y flotando con él, fue arrastrado por la inundación cruzando los estados de Idaho, Washington y Oregón siguiendo el cauce del río Columbia a</span><span style="background-color: white;"> v</span><span face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif"><span style="background-color: white; font-size: 17.6px;">elocidades de más de 20 metros por segundo, según simulaciones numéricas del Servicio Geológico de EEUU (USGS).</span></span></span><span face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif"><span style="background-color: white; font-size: 17.6px;"> </span></span></span></div><div class="js-tweet-text-container"><span style="font-family: arial;"><span class="notranslate" face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white; font-size: 17.6px;"><br /></span></span></div><div class="js-tweet-text-container"><span style="font-family: arial;"><span class="notranslate" face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white; font-size: 17.6px;">Mientras flotaba en las aguas de la inundación sobre lo que hoy es la ciudad de Portland, la carcasa de hielo se desprendió y el pesado meteorito se hundió en las aguas, posándose en el fondo.</span><span face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif"><span style="background-color: white; font-size: 17.6px;"> </span></span><span class="notranslate" face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white; font-size: 17.6px;">En la región se han encontrado cientos de otras </span><span face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white; font-size: 17.6px;">rocas incompatibles con la geología local. Se les llama </span><span class="notranslate" face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white; font-size: 17.6px;">rocas <i>erráticas</i> y fueron transportadas también en <i>balsas</i> de hielo a lo largo del río Columbia durante </span><span class="notranslate" face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white; font-size: 17.6px;">las inundaciones. </span><br />
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<span class="notranslate" face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white; font-size: 17.6px;">Al terminar la inundación, el meteorito quedó expuesto a la atmósfera.</span><span face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif"><span style="background-color: white; font-size: 17.6px;"> </span></span><span class="notranslate" face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white; font-size: 17.6px;">Durante lo siguientes miles de años, la lluvia reaccionó con un mineral raro en la Tierra pero común en los meteoritos, la troilita (FeS), <b>disolviendo</b> entonces lentamente <b>el hierro</b> del lado expuesto de la roca:</span></span></div>
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<tr><td><a href="https://1.bp.blogspot.com/-YQb-BKUw0EA/V_Ol1zbUVkI/AAAAAAAAwkc/HS3GRJWx32cwRhmDexR4p4TfEAT77P1ewCLcB/s1600/Willamette_meteorite_surface_detail.jpg" style="color: #7c7c7c; margin-left: auto; margin-right: auto; text-decoration-line: none;"><span style="font-family: arial;"><img border="0" height="243" src="https://1.bp.blogspot.com/-YQb-BKUw0EA/V_Ol1zbUVkI/AAAAAAAAwkc/HS3GRJWx32cwRhmDexR4p4TfEAT77P1ewCLcB/s400/Willamette_meteorite_surface_detail.jpg" style="background-color: transparent; background: transparent; border: none; box-shadow: rgba(0, 0, 0, 0.1) 0px 0px 0px; padding: 0px; position: relative;" width="400" /></span></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8px;"><span style="font-family: arial;"><span class="notranslate">Las cavidades del meteorito fueron producidas por la disolución del hierro en el </span><br />
<span class="notranslate">lado expuesto a la atmósfera.</span></span></td></tr>
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<span style="font-family: arial;"><span class="notranslate"><span face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif"><span style="background-color: white; font-size: 17.6px;">Poco después de la inundación, </span></span><b style="background-color: white; font-size: 17.6px;">los Clacamas llegaron a Oregón y bautizaron al meteorito como el <i>Visitante del Cielo</i>. </b><span face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white; font-size: 17.6px;">Para ellos,</span><span face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif"><span style="background-color: white; font-size: 17.6px;"> Tomanowos vino a unir la tierra, el agua y el cielo.</span></span></span><span face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif"><span style="background-color: white; font-size: 17.6px;"> </span></span><span class="notranslate" face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white; font-size: 17.6px;">Posiblemente supieran que las rocas metálicas provienen del cielo, una preclaridad que no deja de ser inquietante.</span><span face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif"><span style="background-color: white; font-size: 17.6px;"> </span></span><span class="notranslate" face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white; font-size: 17.6px;">¿Les intrigaba la ausencia de un cráter en el sitio del hallazgo?</span><span face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif"><span style="background-color: white; font-size: 17.6px;"> ¿Vislumbraron como explicación una inundación que tardaría aún miles de años en ser <i>redescubierta</i> para cambiar la historia de la geología? </span></span><span class="notranslate" face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white; font-size: 17.6px;">En cualquier caso, el nombre del meteorito nos recuerda que las culturas precientíficas no eran idiotas, o en todo caso no lo eran más que la nuestra hoy en día.</span><br />
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<span class="notranslate" face=""arial" , "tahoma" , "helvetica" , "freesans" , sans-serif" style="background-color: white; font-size: 17.6px;">Como queriendo confirmar esta última hipótesis, en 1902 un colono llamado Ellis Hughes, buscando </span></span><span style="background-color: white; font-family: arial; font-size: 17.6px;">enriquecerse con la roca,</span><span class="notranslate" style="background-color: white; font-family: arial; font-size: 17.6px;"> decidió trasladarla a sus propias tierras, en secreto.</span><span style="font-family: arial;"><span style="background-color: white; font-size: 17.6px;"> </span></span><span class="notranslate" style="background-color: white; font-family: arial; font-size: 17.6px;">Milenios de descanso pacífico en el valle del río Willamette llegaron a su fin.</span><span style="font-family: arial;"><span style="background-color: white; font-size: 17.6px;"> </span></span><span class="notranslate" style="background-color: white; font-family: arial; font-size: 17.6px;">Pero claro, no es fácil desplazarse varios kilómetros </span><span style="background-color: white; font-family: arial; font-size: 17.6px;">en secreto </span><span class="notranslate" style="background-color: white; font-family: arial; font-size: 17.6px;">con una roca de 15 toneladas, ni siquiera en Oregón. Hughes y su hijo trabajaron de noche durante tres duros meses y f</span><span style="background-color: white; font-family: arial; font-size: 17.6px;">ue durante ese transporte que la roca sufrió severas mutilaciones.</span></div>
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<tr><td><a href="https://2.bp.blogspot.com/-Lg4SSSb6l-4/V_PANfXOlpI/AAAAAAAAwk8/z5NzSoBJYnUAz41PDr8kOrrlUGiY7eGLQCLcB/s1600/hughes-with-meteorite1.png" style="color: #7c7c7c; margin-left: auto; margin-right: auto; text-decoration-line: none;"><span style="font-family: arial; font-size: medium;"><img border="0" height="312" src="https://2.bp.blogspot.com/-Lg4SSSb6l-4/V_PANfXOlpI/AAAAAAAAwk8/z5NzSoBJYnUAz41PDr8kOrrlUGiY7eGLQCLcB/s400/hughes-with-meteorite1.png" style="background-color: transparent; background: transparent; border: none; box-shadow: rgba(0, 0, 0, 0.1) 0px 0px 0px; padding: 0px; position: relative;" width="400" /></span></a></td></tr>
<tr><td class="tr-caption">Una vez hubo trasladado Tomanowos, Hughes <br /> construyó una cabaña alrededor del meteorito, anunció <br />que había caído en su propiedad y comenzó a cobrar<br /> veinticinco centavos por verlo. </td></tr>
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<span style="font-family: arial; font-size: medium;"><div><span style="font-family: arial; font-size: medium;"><br /></span></div></span>Una vez en su propiedad, Hughes comenzó a cobrar veinticinco centavos por ver el meteorito. Sin embargo, su vecino, <span class="notranslate" style="font-family: arial;"><span style="background-color: white; font-size: 17.6px;">no impresionado por el despliegue de idiotez, le demandó asegurando que el meteorito, en realidad, había aterrizado en SU propiedad.</span></span><span style="background-color: white; font-family: arial; font-size: 17.6px;"> </span><span class="notranslate" style="background-color: white; font-family: arial; font-size: 17.6px;">Y para respaldarlo mostró a los jueces un enorme cráter en su terreno.</span><span style="background-color: white; font-family: arial; font-size: 17.6px;"> </span><span class="notranslate" style="background-color: white; font-family: arial; font-size: 17.6px;">Su caso hubo de ser desestimado cuando un tercer vecino de la zona informó de una enorme explosión provocada apenas una semana antes del juicio.</span><div class="js-tweet-text-container" style="background-color: white; font-size: 17.6px;"><span style="font-family: arial;">
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<a href="https://www.blogger.com/blogger.g?blogID=4996769537501094384" style="clear: right; color: #7c7c7c; float: right; margin-bottom: 1em; margin-left: 1em; text-decoration-line: none;"></a><span style="font-family: arial;"><span class="notranslate">Irónicamente, el propietario legal del lugar de aterrizaje de la roca de hierro resultó ser la <i>Compañía de Hierro y Acero de Oregón,</i> que hasta entonces desconocía la existencia del meteorito. Inmediatamente contrató a un guardia que se parapetó sobre la roca día y noche, armado, mientras la compañía apelaba la sentencia.</span> <span class="notranslate">Ganaron el caso en 1905 y vendieron Tomanowos al museo de Nueva York un año después. Las autoridades, igual que ya habían relocalizado a los Clacamas y a otras 20 tribus a una <i>reserva</i>, decidieron también relocalizar a Tomanowos en la otra costa de los EEUU, la que sería la última parada de su billar cósmico. </span></span></div>
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<tr><td><a href="https://3.bp.blogspot.com/-avUoqfxGSFE/V_Ok90-fArI/AAAAAAAAwkU/U1oL1Abu620j6ahyoUXq0nyO8sJNF1CFQCLcB/s1600/The_American_Museum_journal_%2528c1900-%25281918%2529%2529_%252817973455149%2529.jpg" style="color: #7c7c7c; margin-left: auto; margin-right: auto; text-decoration-line: none;"><span style="font-family: arial;"><img border="0" height="232" src="https://3.bp.blogspot.com/-avUoqfxGSFE/V_Ok90-fArI/AAAAAAAAwkU/U1oL1Abu620j6ahyoUXq0nyO8sJNF1CFQCLcB/s400/The_American_Museum_journal_%2528c1900-%25281918%2529%2529_%252817973455149%2529.jpg" style="background-color: transparent; background: transparent; border: none; box-shadow: rgba(0, 0, 0, 0.1) 0px 0px 0px; padding: 0px; position: relative;" width="400" /></span></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8px;"><span class="notranslate" style="font-family: arial;">Tomanowos a principios del siglo XX, antes de ser transportado a Nueva York.</span></td></tr>
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<span style="font-family: arial;">Sorprendentemente,</span><span style="font-family: arial;"> </span><span style="font-family: arial;"><span class="notranslate">la exposición del American Museum of National History no menciona las inundaciones de Missoula, una parte clave de la historia de Tomanowos. Esto a pesar del amplio consenso científico y de la narrativa de sus primeros descubridores.</span> Pero l<span class="notranslate">os descendientes de los Clacamas sí conservan todavía el derecho a acudir al museo a rendir tributo al <i>visitante que reunió el Cielo, el Agua y la Tierra</i>.</span></span></div>
</div>Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com0tag:blogger.com,1999:blog-4996769537501094384.post-6432846734162781652020-05-05T20:46:00.004+02:002022-01-21T20:57:40.233+01:00La tormenta Gloria aísla el sur del Delta del Ebro<span style="font-size: x-small;">[Publicado 2020-05-04 en <a href="https://theconversation.com/la-tormenta-gloria-deja-una-nueva-isla-y-nos-recuerda-el-delicado-equilibrio-del-delta-del-ebro-134463?utm_source=linkedin&utm_medium=linkedinbutton">The Conversation España</a>]</span><br />
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<tr><td class="tr-caption" style="font-size: 12.8px; text-align: center;">Las máquinas de Salvador intentan por tercera vez extender una pista de arena que le permita acceder de nuevo a su salina (al fondo, la <i>montaña</i> de sal), aislada frente a San Carlos de la Rápita (Tarragona). Los anteriores intentos han sido desbaratados por tormentas menos intensas que Gloria.</td></tr>
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Llevamos dos meses luchando contra las olas para reconstruir la barra del Trabucador,<span class="Apple-converted-space"> </span><a href="https://www.diaridetarragona.com/ebre/Les-obres-dInfosa-a-la-barra-del-Trabucador-al-jutjat-20200426-0005.html" style="color: #555768; outline: none; overflow-wrap: break-word; white-space: pre-wrap;">hemos invertido todas nuestras excavadoras y 400 000 euros. Ninguna institución nos ayuda</a>.<span class="Apple-converted-space"> - </span><span style="background-color: white; caret-color: rgb(56, 56, 56); color: #383838; font-style: normal;">Salvador Cavaller</span></div></blockquote>
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<figure class="align-right zoomable" style="border: 0px; caret-color: rgb(56, 56, 56); clear: right; color: #383838; float: right; font-family: "Libre Baskerville", Georgia, Times, "Times New Roman", serif; font-size: 18px; margin: 0px 0px 18px 20px; outline: 0px; padding: 0px; position: relative; text-size-adjust: auto; vertical-align: baseline; width: 237px;"><a href="https://images.theconversation.com/files/331003/original/file-20200428-110734-10jq8vq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip" style="color: #555768; display: block; max-width: 100%; outline: none; overflow-wrap: break-word; text-decoration-line: none; white-space: pre-wrap;"><img alt="" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" src="https://images.theconversation.com/files/331003/original/file-20200428-110734-10jq8vq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/331003/original/file-20200428-110734-10jq8vq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=903&fit=crop&dpr=1 600w, https://images.theconversation.com/files/331003/original/file-20200428-110734-10jq8vq.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=903&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/331003/original/file-20200428-110734-10jq8vq.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=903&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/331003/original/file-20200428-110734-10jq8vq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1134&fit=crop&dpr=1 754w, https://images.theconversation.com/files/331003/original/file-20200428-110734-10jq8vq.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1134&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/331003/original/file-20200428-110734-10jq8vq.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1134&fit=crop&dpr=3 2262w" style="border: none; display: block; margin: 0px; max-width: 100%; outline: 0px; padding: 0px; vertical-align: baseline;" /><div class="enlarge_hint" style="background-color: rgba(0, 0, 0, 0.6); background-image: url("https://cdn.theconversation.com/static/tc/icons/16x16search-white-67f83a253e8e71281277c5cf51a362ac.png"); background-position: 50% 50%; background-repeat: no-repeat; border-bottom-left-radius: 2px; border-top-right-radius: 2px; border: 0px; height: 26px; margin: 0px; opacity: 0; outline: 0px; overflow: hidden; padding: 0px; position: absolute; right: 0px; text-indent: -999em; top: 0px; transition: opacity 0.1s ease-in 0s; vertical-align: baseline; width: 26px;">
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</a><figcaption style="border: 0px; color: #727272; cursor: default; font-family: "Helvetica Neue", Helvetica, sans-serif; font-size: 11px; line-height: 18px; margin: 0px; outline: 0px; padding: 6px 0px 0px; vertical-align: baseline;"><span class="caption" style="border: 0px; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;">Actual estado de la playa del Trabucador, que unía la punta de la Banya (ahora una isla) con el resto del delta. Se distinguen los restos de un puerto deportivo para windsurfistas.</span><span class="Apple-converted-space"> </span><span class="attribution" style="border: 0px; color: #cccccc; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;">Infosa</span></figcaption></figure><br />
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Salvador Cavaller habla de Infosa, una salina que lleva décadas produciendo sal en el delta del Ebro (Tarragona). Técnicamente, su empresa ha dejado de estar en la península ibérica para formar parte de una nueva isla, la decimocuarta mayor de España. Su tamaño, cercano a los 30 km², es similar al de La Graciosa canaria.<span class="Apple-converted-space"> </span></div>
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Los efectos de Gloria</h2>
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El 21 de enero de 2020, el viento y las bajas presiones asociados a la<span class="Apple-converted-space"> </span><a href="https://www.nat-hazards-earth-syst-sci-discuss.net/nhess-2020-75/" style="color: #555768; outline: none; overflow-wrap: break-word; white-space: pre-wrap;">borrasca Gloria</a><span class="Apple-converted-space"> </span>hicieron subir las aguas del Mediterráneo alrededor de un metro. Las olas de hasta 8 metros arrasaron la barra del Trabucador, una estrecha y frágil playa de 6 km de longitud y 120 metros de anchura que unía la punta sur del delta (la punta de la Banya) con el continente.<span class="Apple-converted-space"> </span></div>
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<figure class="align-center zoomable" style="border: 0px; caret-color: rgb(56, 56, 56); color: #383838; font-family: "Libre Baskerville", Georgia, Times, "Times New Roman", serif; font-size: 18px; margin: 0px 0px 18px; outline: 0px; padding: 0px; position: relative; text-size-adjust: auto; vertical-align: baseline;"><a href="https://images.theconversation.com/files/331550/original/file-20200429-51508-13bi6h8.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip" style="color: #555768; display: block; max-width: 100%; outline: none; overflow-wrap: break-word; text-decoration-line: none; white-space: pre-wrap;"><img alt="" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" src="https://images.theconversation.com/files/331550/original/file-20200429-51508-13bi6h8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/331550/original/file-20200429-51508-13bi6h8.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=221&fit=crop&dpr=1 600w, https://images.theconversation.com/files/331550/original/file-20200429-51508-13bi6h8.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=221&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/331550/original/file-20200429-51508-13bi6h8.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=221&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/331550/original/file-20200429-51508-13bi6h8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=278&fit=crop&dpr=1 754w, https://images.theconversation.com/files/331550/original/file-20200429-51508-13bi6h8.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=278&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/331550/original/file-20200429-51508-13bi6h8.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=278&fit=crop&dpr=3 2262w" style="border: none; display: block; margin: 0px; max-width: 100%; outline: 0px; padding: 0px; vertical-align: baseline; width: 600px;" /><div class="enlarge_hint" style="background-color: rgba(0, 0, 0, 0.6); background-image: url("https://cdn.theconversation.com/static/tc/icons/16x16search-white-67f83a253e8e71281277c5cf51a362ac.png"); background-position: 50% 50%; background-repeat: no-repeat; border-bottom-left-radius: 2px; border-top-right-radius: 2px; border: 0px; height: 26px; margin: 0px; opacity: 0; outline: 0px; overflow: hidden; padding: 0px; position: absolute; right: 0px; text-indent: -999em; top: 0px; transition: opacity 0.1s ease-in 0s; vertical-align: baseline; width: 26px;">
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</a><figcaption style="border: 0px; color: #727272; cursor: default; font-family: "Helvetica Neue", Helvetica, sans-serif; font-size: 11px; line-height: 18px; margin: 0px; outline: 0px; padding: 6px 0px 0px; vertical-align: baseline;"><span class="caption" style="border: 0px; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;">Fotografías satelitales (Sentinel) antes (izquierda) y después (derecha) del paso de la tormenta Gloria. A la derecha se ve el lóbulo sur del Delta convertido en una nueva isla.</span><span class="Apple-converted-space"> </span><span class="attribution" style="border: 0px; color: #cccccc; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;"><a class="source" href="https://sentinel.esa.int/web/sentinel/home" style="color: #555768; display: inline; max-width: 100%; outline: none; overflow-wrap: break-word; text-decoration-line: none; white-space: pre-wrap;">Sentinel (ESA)</a></span></figcaption></figure><br />
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Gloria ha puesto de manifiesto una vez más la fragilidad de los deltas. La retención del sedimento en los embalses está poniendo en peligro muchos de estos importantes ecosistemas en el mundo. El sedimento que cada tormenta se lleva del delta ya no es repuesto por el río en los años siguientes.</div>
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<i><span style="caret-color: rgb(56, 56, 56); color: #383838;">Mi familia tiene una propiedad en la desembocadura del delta y de niño nos solíamos acercar a ver el</span><span class="Apple-converted-space" style="caret-color: rgb(56, 56, 56); color: #383838;"> </span><a href="http://ingenieria-civil.org/GOING/obra.php?id=85" style="caret-color: rgb(56, 56, 56); color: #555768; outline: none; overflow-wrap: break-word; white-space: pre-wrap;">faro de Buda</a></i><span style="color: #383838; font-style: normal;">, cuenta Salvador.</span><span class="Apple-converted-space" style="color: #383838; font-style: normal;"> </span></div>
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Hoy ese faro está casi<span class="Apple-converted-space"> </span><a href="https://www.lavanguardia.com/natural/20190224/46479837429/delta-faro-regresion.html" style="color: #555768; outline: none; overflow-wrap: break-word; white-space: pre-wrap;">3 km mar adentro</a>. Fue construido en tierra en 1864. Cada año el mar le gana unos metros al delta y hoy apenas se le distingue en el horizonte.<span class="Apple-converted-space"> </span></div>
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<figure class="align-center zoomable" style="border: 0px; caret-color: rgb(56, 56, 56); color: #383838; font-family: "Libre Baskerville", Georgia, Times, "Times New Roman", serif; font-size: 18px; margin: 0px 0px 18px; outline: 0px; padding: 0px; position: relative; text-size-adjust: auto; vertical-align: baseline;"><a href="https://images.theconversation.com/files/331004/original/file-20200428-110761-1ik73d9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip" style="color: #555768; display: block; max-width: 100%; outline: none; overflow-wrap: break-word; text-decoration-line: none; white-space: pre-wrap;"><img alt="" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" src="https://images.theconversation.com/files/331004/original/file-20200428-110761-1ik73d9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/331004/original/file-20200428-110761-1ik73d9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=290&fit=crop&dpr=1 600w, https://images.theconversation.com/files/331004/original/file-20200428-110761-1ik73d9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=290&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/331004/original/file-20200428-110761-1ik73d9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=290&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/331004/original/file-20200428-110761-1ik73d9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=364&fit=crop&dpr=1 754w, https://images.theconversation.com/files/331004/original/file-20200428-110761-1ik73d9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=364&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/331004/original/file-20200428-110761-1ik73d9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=364&fit=crop&dpr=3 2262w" style="border: none; display: block; margin: 0px; max-width: 100%; outline: 0px; padding: 0px; vertical-align: baseline; width: 600px;" /><div class="enlarge_hint" style="background-color: rgba(0, 0, 0, 0.6); background-image: url("https://cdn.theconversation.com/static/tc/icons/16x16search-white-67f83a253e8e71281277c5cf51a362ac.png"); background-position: 50% 50%; background-repeat: no-repeat; border-bottom-left-radius: 2px; border-top-right-radius: 2px; border: 0px; height: 26px; margin: 0px; opacity: 0; outline: 0px; overflow: hidden; padding: 0px; position: absolute; right: 0px; text-indent: -999em; top: 0px; transition: opacity 0.1s ease-in 0s; vertical-align: baseline; width: 26px;">
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</a><figcaption style="border: 0px; color: #727272; cursor: default; font-family: "Helvetica Neue", Helvetica, sans-serif; font-size: 11px; line-height: 18px; margin: 0px; outline: 0px; padding: 6px 0px 0px; vertical-align: baseline;"><span class="caption" style="border: 0px; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;">El faro de Buda en los años 50.</span><span class="Apple-converted-space"> </span><span class="attribution" style="border: 0px; color: #cccccc; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;">Author provided</span></figcaption></figure><br />
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El delta del Ebro, un producto humano</h2>
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Para salvar el delta, hoy barajamos al fin la eliminación de presas poco necesarias y el dragado de otras para restaurar el tránsito natural del sedimento y la fauna, siguiendo la<span class="Apple-converted-space"> </span><a href="https://www.americanrivers.org/threats-solutions/restoring-damaged-rivers/dam-removal-map/" style="color: #555768; outline: none; overflow-wrap: break-word; white-space: pre-wrap;">estela de EE UU</a>.<span class="Apple-converted-space"> </span></div>
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Sin embargo, tanto el del Ebro como muchos otros deltas son en realidad<span class="Apple-converted-space"> </span><a href="https://www.nature.com/articles/srep01926" style="color: #555768; outline: none; overflow-wrap: break-word; white-space: pre-wrap;">paisajes tan antropogénicos como las presas</a><span class="Apple-converted-space"> </span>que los amenazan.<span class="Apple-converted-space"> </span></div>
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En el caso del delta del Ebro, existen datos muy completos sobre su origen y la evolución. Las primeras descripciones legadas en el periodo romano hablan de un delta de tamaño insignificante. La datación del suelo indica que su formación comenzó hace unos cuatro mil años y el principal sospechoso es el ser humano. Concretamente, los habitantes de Iberia que en ese periodo cambiaron su vida cazadora y recolectora por la<span class="Apple-converted-space"> </span><a href="https://www.sciencedirect.com/science/article/abs/pii/S034181621000010X" style="color: #555768; outline: none; overflow-wrap: break-word; white-space: pre-wrap;">agricultura, talando grandes extensiones de bosque</a><span class="Apple-converted-space"> </span>y dejando el suelo desprotegido. La erosión avanzó entonces entre diez y mil veces más rápidamente, según los lugares.</div>
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<figure class="align-right zoomable" style="border: 0px; caret-color: rgb(56, 56, 56); clear: right; color: #383838; float: right; font-family: "Libre Baskerville", Georgia, Times, "Times New Roman", serif; font-size: 18px; margin: 0px 0px 18px 20px; outline: 0px; padding: 0px; position: relative; text-size-adjust: auto; vertical-align: baseline; width: 237px;"><a href="https://images.theconversation.com/files/331385/original/file-20200429-51500-18i9yxz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip" style="color: #555768; display: block; max-width: 100%; outline: none; overflow-wrap: break-word; text-decoration-line: none; white-space: pre-wrap;"><img alt="" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" src="https://images.theconversation.com/files/331385/original/file-20200429-51500-18i9yxz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/331385/original/file-20200429-51500-18i9yxz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=354&fit=crop&dpr=1 600w, https://images.theconversation.com/files/331385/original/file-20200429-51500-18i9yxz.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=354&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/331385/original/file-20200429-51500-18i9yxz.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=354&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/331385/original/file-20200429-51500-18i9yxz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=445&fit=crop&dpr=1 754w, https://images.theconversation.com/files/331385/original/file-20200429-51500-18i9yxz.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=445&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/331385/original/file-20200429-51500-18i9yxz.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=445&fit=crop&dpr=3 2262w" style="border: none; display: block; margin: 0px; max-width: 100%; outline: 0px; padding: 0px; vertical-align: baseline;" /><div class="enlarge_hint" style="background-color: rgba(0, 0, 0, 0.6); background-image: url("https://cdn.theconversation.com/static/tc/icons/16x16search-white-67f83a253e8e71281277c5cf51a362ac.png"); background-position: 50% 50%; background-repeat: no-repeat; border-bottom-left-radius: 2px; border-top-right-radius: 2px; border: 0px; height: 26px; margin: 0px; opacity: 0; outline: 0px; overflow: hidden; padding: 0px; position: absolute; right: 0px; text-indent: -999em; top: 0px; transition: opacity 0.1s ease-in 0s; vertical-align: baseline; width: 26px;">
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</a><figcaption style="border: 0px; color: #727272; cursor: default; font-family: "Helvetica Neue", Helvetica, sans-serif; font-size: 11px; line-height: 18px; margin: 0px; outline: 0px; padding: 6px 0px 0px; vertical-align: baseline;"><span class="caption" style="border: 0px; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;">El Castildetierra (Bardenas Reales) es un paisaje creado por la erosión de sedimentos de distinta dureza acumulados en la cuenca sedimentaria del Ebro hace entre 50 y 10 millones de años. Los estratos más duros que protegen estos montículos de la erosión son rocas calcáreas que se forman en el fondo de lagos.</span><span class="attribution" style="border: 0px; color: #cccccc; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;"><a class="source" href="https://es.wikipedia.org/wiki/Archivo:El_Castildetierra.JPG" style="color: #555768; display: inline; max-width: 100%; outline: none; overflow-wrap: break-word; text-decoration-line: none; white-space: pre-wrap;">Yurki/Wikimedia Commons</a>,<span class="Apple-converted-space"> </span><a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/" style="color: #555768; display: inline; max-width: 100%; outline: none; overflow-wrap: break-word; text-decoration-line: none; white-space: pre-wrap;">CC BY-SA</a></span></figcaption></figure><br />
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Antes de la agricultura, el sedimento provenía (en mucha menor cantidad) de los Pirineos, de la cordillera ibérica y de la erosión de la cuenca del Ebro, responsable de parajes tan característicos como las<span class="Apple-converted-space"> </span><a href="https://es.wikipedia.org/wiki/Bardenas_Reales" style="color: #555768; outline: none; overflow-wrap: break-word; white-space: pre-wrap;">Bardenas Reales</a><span class="Apple-converted-space"> </span>(Navarra). La vegetación autóctona protegía el suelo de la erosión y por eso el aporte de sedimento al delta era mucho menor.<span class="Apple-converted-space"> </span></div>
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Además, muchos de los ríos de la península ibérica, también el Ebro, desembocaban en estuarios en lugar de deltas porque el nivel del mar acababa de subir unos 120 metros debido a la fusión del hielo polar. Esa subida del nivel del mar culminó hace 6 000 años inundando los valles de los ríos junto a sus desembocaduras. Luego, la agricultura aceleró el relleno con sedimento de esos estuarios.<span class="Apple-converted-space"> </span></div>
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Los lagos que se transformaron en río</h2>
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Pero el río Ebro no siempre fluyó hasta al Mediterráneo. Hasta hace unos 10 millones de años (recientemente, en términos geológicos) todo ese sedimento quedaba atrapado en un enorme conjunto de lagos en el interior de su cuenca hidrográfica, que abarca desde los Monegros y Lleida hasta las propias Bardenas Reales (Navarra) y La Rioja.<span class="Apple-converted-space"> </span></div>
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Después, ese gran lago, que se había ido llenando de sedimento hasta alcanzar unos 700 metros de elevación, se desbordó vertiendo sus aguas hacia el Mediterráneo.</div>
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Conforme el nuevo río (el Ebro) se encajaba a través de la cordillera costero-catalana donde se produjo el desbordamiento, el sedimento acumulado en la cuenca interior empezó también a ser excavado de nuevo por la erosión –así se formó el fotogénico relieve actual–. Este material fue transportado a lo largo del Ebro y sus afluentes hasta el mar.</div>
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<figure style="border: 0px; caret-color: rgb(56, 56, 56); color: #383838; font-family: "Libre Baskerville", Georgia, Times, "Times New Roman", serif; font-size: 18px; margin: 0px 0px 18px; outline: 0px; padding: 0px; position: relative; text-size-adjust: auto; vertical-align: baseline;"><div class="fluidvids" style="border: 0px; margin: 0px; max-width: 100%; outline: 0px; padding: 354.531px 0px 0px; position: relative; vertical-align: baseline; width: 600px;">
<iframe allowfullscreen="" class="fluidvids-item" data-fluidvids="loaded" frameborder="0" height="260" src="https://www.youtube.com/embed/q___eADYvJM?wmode=transparent&start=0" style="border-style: initial; border-width: 0px; display: block; height: 354.531px; left: 0px; margin: 0px; outline: 0px; padding: 0px; position: absolute; top: 0px; vertical-align: baseline; width: 600px;" width="440"></iframe></div>
<figcaption style="border: 0px; color: #727272; cursor: default; font-family: "Helvetica Neue", Helvetica, sans-serif; font-size: 11px; line-height: 18px; margin: 0px; outline: 0px; padding: 6px 0px 0px; vertical-align: baseline;"><span class="caption" style="border: 0px; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;">Simulación geofísica de la evolución de la cuenca del Ebro combinando movimientos tectónicos con el cálculo de la erosión.</span></figcaption></figure><br />
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La parte invisible de los deltas</h2>
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Fruto de esos 10 millones de años de transporte por el río, hoy el volumen de sedimentos es mucho mayor de lo que se aprecia a simple vista. Abarca una longitud de hasta 200 km a lo largo de la costa y penetra hasta 50 km mar adentro. En total, alberga unos 40 000 kilómetros cúbicos de arena acumulados durante 10 millones de años.<span class="Apple-converted-space"> </span></div>
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La parte emergida de los deltas, la que visitamos en vacaciones y compartimos con cientos de especies de aves, es una pequeña parte de una enorme masa submarina de sedimento.<span class="Apple-converted-space"> </span></div>
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<figure class="align-right zoomable" style="border: 0px; caret-color: rgb(56, 56, 56); clear: right; color: #383838; float: right; font-family: "Libre Baskerville", Georgia, Times, "Times New Roman", serif; font-size: 18px; margin: 0px 0px 18px 20px; outline: 0px; padding: 0px; position: relative; text-size-adjust: auto; vertical-align: baseline; width: 237px;"><a href="https://images.theconversation.com/files/328838/original/file-20200418-152563-ng8veq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip" style="color: #555768; display: block; max-width: 100%; outline: none; overflow-wrap: break-word; text-decoration-line: none; white-space: pre-wrap;"><img alt="" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" src="https://images.theconversation.com/files/328838/original/file-20200418-152563-ng8veq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/328838/original/file-20200418-152563-ng8veq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/328838/original/file-20200418-152563-ng8veq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/328838/original/file-20200418-152563-ng8veq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/328838/original/file-20200418-152563-ng8veq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/328838/original/file-20200418-152563-ng8veq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/328838/original/file-20200418-152563-ng8veq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" style="border: none; display: block; margin: 0px; max-width: 100%; outline: 0px; padding: 0px; vertical-align: baseline;" /><div class="enlarge_hint" style="background-color: rgba(0, 0, 0, 0.6); background-image: url("https://cdn.theconversation.com/static/tc/icons/16x16search-white-67f83a253e8e71281277c5cf51a362ac.png"); background-position: 50% 50%; background-repeat: no-repeat; border-bottom-left-radius: 2px; border-top-right-radius: 2px; border: 0px; height: 26px; margin: 0px; opacity: 0; outline: 0px; overflow: hidden; padding: 0px; position: absolute; right: 0px; text-indent: -999em; top: 0px; transition: opacity 0.1s ease-in 0s; vertical-align: baseline; width: 26px;">
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</a><figcaption style="border: 0px; color: #727272; cursor: default; font-family: "Helvetica Neue", Helvetica, sans-serif; font-size: 11px; line-height: 18px; margin: 0px; outline: 0px; padding: 6px 0px 0px; vertical-align: baseline;"><span class="caption" style="border: 0px; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;">Torres eléctricas en la playa del trabucador, 2013.</span><span class="Apple-converted-space"> </span><span class="attribution" style="border: 0px; color: #cccccc; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;"><span class="source" style="border: 0px; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;">Quynh Nhu Hoang</span>,<span class="Apple-converted-space"> </span><span class="license" style="border: 0px; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;">Author provided</span></span></figcaption></figure><br />
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Esa fracción visible es el resultado de un frágil equilibrio entre la erosión de los continentes, el transporte del sedimento por los ríos, la corriente y dinámica costera y la subida del nivel del mar (relacionada con el cambio climático).<span class="Apple-converted-space"> </span></div>
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A los procesos mencionados se suman la progresiva compactación del sedimento y el hundimiento de la litosfera terrestre bajo el creciente peso del delta (debido a que la litosfera descansa sobre el magma fluido del manto terrestre, un fenómeno conocido como<span class="Apple-converted-space"> </span><em style="border: 0px; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;">isostasia</em>).<span class="Apple-converted-space"> </span></div>
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Estos dos últimos mecanismos son los principales responsables, por ejemplo, del peligro creciente que corre el delta del Rin (Holanda). Su mayor parte se encuentra hoy a varios metros bajo el nivel del mar y protegido por diques.<span class="Apple-converted-space"> </span></div>
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<iframe allowfullscreen="" class="fluidvids-item" data-fluidvids="loaded" frameborder="0" height="260" src="https://www.youtube.com/embed/2mrHUHaT8vg?wmode=transparent&start=0" style="border-style: initial; border-width: 0px; display: block; height: 354.531px; left: 0px; margin: 0px; outline: 0px; padding: 0px; position: absolute; top: 0px; vertical-align: baseline; width: 600px;" width="440"></iframe></div>
<figcaption style="border: 0px; color: #727272; cursor: default; font-family: "Helvetica Neue", Helvetica, sans-serif; font-size: 11px; line-height: 18px; margin: 0px; outline: 0px; padding: 6px 0px 0px; vertical-align: baseline;"><span class="caption" style="border: 0px; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;">La barra del Trabucador en el lugar donde las olas la arrasaron.</span></figcaption></figure><br />
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Decisiones humanas</h2>
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A estos mecanismos hay que añadir a la humanidad, autoexcluida de esa naturaleza y autoerigida en árbitro que designa qué es natural y qué artificial. Primero formamos el delta talando bosques y usándolos para la agricultura, promoviendo la erosión del suelo. Luego construimos presas que impiden que ese sedimento alcance la costa. Ahora necesitamos excavadoras para restaurar lo que primero creamos y luego destruimos. Como decía el poeta Bloem sobre su tierra (el antropogénico delta del Rin): <i>Wat is natuur </i><i>nog </i><i>in dit land,</i> “¿qué queda de natural en este país?”, ¿qué debemos <i>preservar</i>?<span class="Apple-converted-space"> </span></div>
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<a href="https://1.bp.blogspot.com/-FzVPUneaArQ/XrPHleqDpvI/AAAAAAABFpc/yL15nvAGMOAdQFNbXndN1AdPNvsFgECmgCNcBGAsYHQ/s1600/WhatsApp%2BImage%2B2020-03-24%2Bat%2B17.16.04%2Bantiguo%2Bcentro%2Bde%2Bwindsurf.jpeg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="720" data-original-width="1080" height="213" src="https://1.bp.blogspot.com/-FzVPUneaArQ/XrPHleqDpvI/AAAAAAABFpc/yL15nvAGMOAdQFNbXndN1AdPNvsFgECmgCNcBGAsYHQ/s320/WhatsApp%2BImage%2B2020-03-24%2Bat%2B17.16.04%2Bantiguo%2Bcentro%2Bde%2Bwindsurf.jpeg" width="320" /></a></div>
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Hoy, la pandemia lo ha paralizado todo, pero en algún momento<span class="Apple-converted-space"> </span><a href="https://www.diaridetarragona.com/ebre/Les-obres-dInfosa-a-la-barra-del-Trabucador-al-jutjat-20200426-0005.html" style="color: #555768; outline: none; overflow-wrap: break-word; white-space: pre-wrap;">los gestores, los científicos y los ingenieros tendrán que buscar respuestas</a><span class="Apple-converted-space"> </span>y reencontrar un equilibrio. La removilización de sedimento o la<span class="Apple-converted-space"> </span><a href="https://theconversation.com/eliminar-embalses-y-presas-abandonadas-un-respiro-para-los-rios-116293" style="color: #555768; outline: none; overflow-wrap: break-word; white-space: pre-wrap;">eliminación de presas</a><span class="Apple-converted-space"> </span>son soluciones que se deben sopesar con otros intereses.<span class="Apple-converted-space"> </span>Pero el delta del Ebro<span class="Apple-converted-space"> </span><a href="https://theconversation.com/aprendamos-de-los-desastres-ambientales-del-delta-del-ebro-y-el-mar-menor-131096" style="color: #555768; outline: none; overflow-wrap: break-word; white-space: pre-wrap;">ya nos ha enseñado</a><span class="Apple-converted-space"> </span>que cada vez que desafiamos los equilibrios naturales, más tarde o más temprano, lo pagamos.<br />
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Actualización<br />
La empresa ha conseguido comunicar la isla con el resto del delta.<br />
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<br /><iframe allowfullscreen='allowfullscreen' webkitallowfullscreen='webkitallowfullscreen' mozallowfullscreen='mozallowfullscreen' width='320' height='266' src='https://www.blogger.com/video.g?token=AD6v5dysBZIimcxe93Obi0wGsGQmlqQ3JskT-cZOek6pEi3vAgjVXq0jEY3Hrwub60Q0wCHrF4fv-BwOCT1Mv9_1TQ' class='b-hbp-video b-uploaded' frameborder='0'></iframe></div>
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-yBJt87Qextk/XrPHTLWiZAI/AAAAAAABFpU/_9rT4b821RQnOjq4MOoN_rDTyIULViCQgCNcBGAsYHQ/s1600/Trabucador%2Bbar%2Bbefore%2BGloria%2B-%2Bby%2BChristian%2BLang.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1199" data-original-width="1600" height="239" src="https://1.bp.blogspot.com/-yBJt87Qextk/XrPHTLWiZAI/AAAAAAABFpU/_9rT4b821RQnOjq4MOoN_rDTyIULViCQgCNcBGAsYHQ/s320/Trabucador%2Bbar%2Bbefore%2BGloria%2B-%2Bby%2BChristian%2BLang.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Trabucador bar before Gloria - by Christian Lang</td></tr>
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-FzVPUneaArQ/XrPHleqDpvI/AAAAAAABFpc/yL15nvAGMOAdQFNbXndN1AdPNvsFgECmgCNcBGAsYHQ/s1600/WhatsApp%2BImage%2B2020-03-24%2Bat%2B17.16.04%2Bantiguo%2Bcentro%2Bde%2Bwindsurf.jpeg" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="720" data-original-width="1080" height="213" src="https://1.bp.blogspot.com/-FzVPUneaArQ/XrPHleqDpvI/AAAAAAABFpc/yL15nvAGMOAdQFNbXndN1AdPNvsFgECmgCNcBGAsYHQ/s320/WhatsApp%2BImage%2B2020-03-24%2Bat%2B17.16.04%2Bantiguo%2Bcentro%2Bde%2Bwindsurf.jpeg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: 12.8px;">Trabucador bar before Gloria - by Infosa</span></td></tr>
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Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com0tag:blogger.com,1999:blog-4996769537501094384.post-63190615087322306942020-04-09T12:02:00.001+02:002020-04-13T11:01:19.147+02:00Lithospheric slab bouyancy during plate convergence - Python code for an analytic solutionThis code relates to the Boonma et al. (2019) paper: Lithospheric mantle buoyancy: the role of tectonic convergence and mantle composition.<br />
<a href="https://www.nature.com/articles/s41598-019-54374-w">https://www.nature.com/articles/s41598-019-54374-w</a><br />
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It is my analytical approach to the same problem. <br />
It calculates the evolution of lithospheric bouyancy as a function of convergence rate, and initial density contrast.<br />
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Edit parameters in lines 27 to 35. Then run the code clicking the 'play' symbol.<br />
Then watch the results looking at the grapic output (click the top left icon).<br />
<iframe height="800px" width="100%" src="https://repl.it/@DanielGarciaCas/buoyancy?lite=true" scrolling="no" frameborder="no" allowtransparency="true" allowfullscreen="true" sandbox="allow-forms allow-pointer-lock allow-popups allow-same-origin allow-scripts allow-modals"></iframe>Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com0tag:blogger.com,1999:blog-4996769537501094384.post-91283085050730318042019-11-21T17:40:00.001+01:002022-01-21T20:59:40.154+01:00Habitabilidad planetaria, Biosphere-2 y la primera vez que supe de Bannon<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-N1qMQKr79T4/Xe6JyluCNJI/AAAAAAABEh0/UqwXwZqfELA8lfF-w-lQFOkIHrTdF35LACNcBGAsYHQ/s1600/Venus_transit.jpg" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="613" data-original-width="706" height="277" src="https://1.bp.blogspot.com/-N1qMQKr79T4/Xe6JyluCNJI/AAAAAAABEh0/UqwXwZqfELA8lfF-w-lQFOkIHrTdF35LACNcBGAsYHQ/s320/Venus_transit.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: "helvetica neue light"; font-size: 9.5pt;">El tránsito solar de Venus en junio de 2012 resalta su <br />atmósfera gracias a la dispersión y refracción de la luz del Sol.<br />Credit: JAXA/NASA/Lockheed Martin</span><!--EndFragment--></td></tr>
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La de físico es una profesión que te legitima para hacer cosas como considerar la Tierra como una esfera perfecta justo a la distancia del Sol que hace su temperatura habitable. Si esa esfera estuviera más lejos, su temperatura de equilibrio radiativo sería demasiado baja. Si nuestra estrella fuera de mayor tamaño o luminosidad, nuestra bolita sería demasiado calurosa para albergar agua líquida y ya no sería el <i>blue marble</i>. Jugar con la ley de Stefan-Boltzman es divertido porque, sustituyendo la temperatura y el radio del Sol (<i>T<span style="font-size: xx-small;">ef</span></i>=5505 ºC; <i>R*</i>=695.000 km) y su distancia a la Tierra (<i>a</i>=149 millones de km), nos predice una temperatura de equilibrio radiativo de 5.4 confortables grados Celsius, bastante cercana a la que disfrutamos.<br />
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<a href="https://1.bp.blogspot.com/-Sy4V5SpDA2o/Xdax3NGkm4I/AAAAAAABEdg/iQOF2xJFLuctWwBHODBpANnbnUKmTivAQCNcBGAsYHQ/s1600/Screen%2BShot%2B2019-11-21%2Bat%2B16.48.20.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="204" data-original-width="372" height="109" src="https://1.bp.blogspot.com/-Sy4V5SpDA2o/Xdax3NGkm4I/AAAAAAABEdg/iQOF2xJFLuctWwBHODBpANnbnUKmTivAQCNcBGAsYHQ/s200/Screen%2BShot%2B2019-11-21%2Bat%2B16.48.20.png" width="200" /></a></div>
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Puedes modificar los valores en este script y calcular T_eq pulsando el 'play':</div>
<iframe allowfullscreen="" frameborder="0" height="356" marginheight="0" marginwidth="0" src="https://trinket.io/embed/python/5490ae21f2" width="100%"></iframe>
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La fórmula funciona bastante bien para Mercurio y para Marte y la tentación es pensar que esta ley dará igual de buenos resultados en todos los planetas, pero las cosas no son tan fáciles. Por ejemplo, aplicando la fórmula a Venus obtienes 66 ºC, muy lejos de los tórridos 464 ºC medidos por las misiones espaciales. Se sabe que la principal causa de esta disparidad es el efecto invernadero de la densa atmósfera de Venus.<br />
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Pero los mecanismos que hacen que un planeta resulte habitable son muy <br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-Jh37H2KyDzM/Xe6WUouPskI/AAAAAAABEiA/MhmS2Xi5g0MPT5DO307afzxnmvtyMaL3ACNcBGAsYHQ/s1600/Screen%2BShot%2B2019-12-09%2Bat%2B19.44.56.png" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="770" data-original-width="846" height="291" src="https://1.bp.blogspot.com/-Jh37H2KyDzM/Xe6WUouPskI/AAAAAAABEiA/MhmS2Xi5g0MPT5DO307afzxnmvtyMaL3ACNcBGAsYHQ/s320/Screen%2BShot%2B2019-12-09%2Bat%2B19.44.56.png" width="320" /></a></td></tr>
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La atmósfera de un planeta determina </div>
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su clima y está a la vez muy ligada a la </div>
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tectónica de placas, que facilita el reciclado </div>
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del carbono emitido en volcanes de </div>
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vuelta al manto.</div>
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La ilustración es del libro que próximamente </div>
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publicaremos en ed. Marcombo: </div>
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<i>(In-)Habitabilidad planetaria</i>, </div>
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por Butturini y coautores, 2020. </div>
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diversos e interactúan de formas muy complejas. La vida, por ejemplo, ha ido modelando el ciclo del agua, del carbono y del oxígeno en la Tierra, además de su albedo. Y todos estos componentes son esenciales para regular el clima. El ciclo del agua determina a qué velocidad se erosionan las rocas silíceas en la superficie de la Tierra, y esa erosión es clave en la captura del CO2 atmosférico y su fijación natural en forma de roca en el fondo marino. Sin erosión, nada limita el efecto invernadero del CO2.<br />
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La gran pregunta entonces es:<br />
<b>¿Cómo un sistema tan complejo ha sido capaz de mantener su habitabilidad de forma continua desde casi la <a href="https://twitter.com/danigeos/status/1197545352699744257?ref_src=twsrc%5Etfw%7Ctwcamp%5Etweetembed%7Ctwterm%5E1197545352699744257&ref_url=http%3A%2F%2Fretosterricolas.blogspot.com%2F">formación de la Tierra hace 4.400 millones de años</a>?</b><br />
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Hace 7 años conocí a los creadores de un proyecto que los mayores de 40 quizá recuerden de las noticias de la época:<br />
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<a href="https://1.bp.blogspot.com/-bpRC93x7eLo/Xda2ljSRC4I/AAAAAAABEdw/bWt9F_Uu08AbjRthRq2HORB7NEZ4sncygCNcBGAsYHQ/s1600/bannerbio2ocean.jpg" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="587" data-original-width="980" height="191" src="https://1.bp.blogspot.com/-bpRC93x7eLo/Xda2ljSRC4I/AAAAAAABEdw/bWt9F_Uu08AbjRthRq2HORB7NEZ4sncygCNcBGAsYHQ/s320/bannerbio2ocean.jpg" width="320" /></a><br />
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<i><a href="https://en.wikipedia.org/wiki/Biosphere_2">Biosphere 2</a> fue </i>un gigantesco espacio de 12.700 m2 completamente sellado y aislado en medio del desierto de Arizona, ideado y desarrollado por <a href="https://en.wikipedia.org/wiki/John_P._Allen">John P. Allen</a> y un variopinto grupo de ingenieros, artistas y científicos. Habitado por 8 humanos, el recinto acristalado fue diseñado para evitar cualquier intercambio de masa con el exterior durante años. El oxígeno respirado por las plantas y animales era regenerado por la fotosíntesis. El agua evaporada del suelo o transpirada por las plantas era recogida en zonas de condensación. Los desechos de todas las actividades humanas eran reciclados dentro de la nave en forma de abono. El agua de irrigación evapotranspirada por las plantas era recogida en zonas de condensación. Incluso la dilatación diurna del aire se acomodaba por medio de unas membranas elásticas gigantes que evitaban la fractura del aislamiento de cristal.</div>
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El resultado del gigantesco experimento fue aleccionador: A los problemas para mantener algunos de los ecosistemas como el marino, pronto se sumó la eclosión de algunas especies como hormigas, cucarachas y enredaderas en cantidades inesperadas. Llegó a haber reproducción animal y vegetal, aunque la mayoría de vertebrados e insectos polinizadores se extinguió. Pero desde el punto de vista científico y técnico, el problema más complejo fue detectar la razón por la que <b>los niveles de oxígeno no se mantuvieron</b> como se esperaba en base al balance entre fotosíntesis y respiración. Tras mucho análisis, se supo que el O2 era absorbido por la <b>reacción del cemento de la estructura</b> con la atmósfera de la nave.<br />
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Pero lo peor estaba por llegar: En el tránsito entre su primera misión (1991-1993) y la segunda, <i>Biosphere-2</i> tuvo la <a href="http://www.motherjones.com/politics/2016/08/stephen-bannon-donald-trump-biosphere-2-arizona">mala fortuna de cruzarse en el camino de Steve K. Bannon</a>, sí, el director de campaña y <b>embajador europeo de Donald Trump</b>. El entonces desconocido Bannon aprovechó mediáticamente las complicaciones que encontró Biosphere-2 y acabó haciéndose con el control financiero del proyecto y desbaratándolo.<br />
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<a href="https://1.bp.blogspot.com/-498Y_6L89LU/Xda3zAVHyNI/AAAAAAABEeA/XONE_dFUT5w6RkCB7BeT02S3VJ0kSBjlQCNcBGAsYHQ/s1600/bannon_0.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="556" data-original-width="989" height="179" src="https://1.bp.blogspot.com/-498Y_6L89LU/Xda3zAVHyNI/AAAAAAABEeA/XONE_dFUT5w6RkCB7BeT02S3VJ0kSBjlQCNcBGAsYHQ/s320/bannon_0.jpg" width="320" /></a></div>
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Desde entonces el lugar se ha reconvertido en destino turístico sin valor científico alguno. Pero el audaz experimento ayudó a comprender mejor la inestabilidad de los ecosistemas y la dificultad de la colonización de otros planetas. Mostró la enorme complejidad de mantener habitable un pequeño ecosistema cerrado y su inherente inestabilidad.<br />
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Y lo más importante para mí: cuando Bannon llegó al poder, John y sus amigos ya me habían avisado de qué se le venía encima al mundo!<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-2S1B_dk1meU/Xda7nY6CQdI/AAAAAAABEeM/y1pHCzirFZwuw98Bv6DJWDP1G5kLlL0XwCNcBGAsYHQ/s1600/2016-08%2BDani%252C%2BJohn%2BAllen%2BDSC00336%2Bcrop.jpg" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="701" data-original-width="699" height="320" src="https://1.bp.blogspot.com/-2S1B_dk1meU/Xda7nY6CQdI/AAAAAAABEeM/y1pHCzirFZwuw98Bv6DJWDP1G5kLlL0XwCNcBGAsYHQ/s320/2016-08%2BDani%252C%2BJohn%2BAllen%2BDSC00336%2Bcrop.jpg" width="319" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">John Allen and myself at his Institute of Ecotechnics in New Mexico, 2016</td></tr>
</tbody></table>
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See also:<br />
<ul>
<li>Mother Jones <a href="http://www.motherjones.com/politics/2016/08/stephen-bannon-donald-trump-biosphere-2-arizona">article on Bannon and Biosphere 2</a>.</li>
<li><span face="sans-serif" style="background-color: white; font-size: 17.145px;">Allen, John (December 1991). </span><a class="external text" href="https://archive.org/details/biosphere2humane00alle" rel="nofollow" style="background-color: white; background: linear-gradient(transparent, transparent) right center no-repeat, url("/w/resources/src/mediawiki.skinning/images/external-ltr.svg?59558") rgb(255, 255, 255); color: #663366; font-family: sans-serif; font-size: 17.145px; padding-right: 13px; text-decoration-line: none;"><i>Biosphere 2: The human experiment</i></a><span face="sans-serif" style="background-color: white; font-size: 17.145px;">. </span><a href="https://en.wikipedia.org/wiki/International_Standard_Book_Number" style="background: none rgb(255, 255, 255); color: #5a3696; font-family: sans-serif; font-size: 17.145px; text-decoration-line: none;" title="International Standard Book Number">ISBN</a><span face="sans-serif" style="background-color: white; font-size: 17.145px;"> </span><a href="https://en.wikipedia.org/wiki/Special:BookSources/978-0140153927" style="background: none rgb(255, 255, 255); color: #5a3696; font-family: sans-serif; font-size: 17.145px; text-decoration-line: none;" title="Special:BookSources/978-0140153927"><bdi>978-0140153927</bdi></a><span face="sans-serif" style="background-color: white; font-size: 17.145px;">.</span></li>
<li><a href="https://en.wikipedia.org/wiki/Faint_young_Sun_paradox">Faint young Sun paradox - Wikipedia</a></li>
</ul>
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<br />Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com0tag:blogger.com,1999:blog-4996769537501094384.post-79149766832536243732019-03-04T12:53:00.006+01:002022-01-21T21:01:39.008+01:00Cómo cambiarán los continentes en el futuro<div class="MsoNormal">
<span lang="ES" style="font-size: x-small; mso-ansi-language: ES;"><o:p>[Ampliación de una contribución en <a href="https://www.lavanguardia.com/ciencia/planeta-tierra/20190304/46793824091/preguntas-big-vang-forma-continentes-cambia-nivel-mar.html">La Vanguardia</a>]</o:p></span></div>
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<span lang="ES" style="mso-ansi-language: ES;"><b><i>Preguntas Big-Vang (La Vanguardia): ¿Cómo cambiarán los continentes en el futuro?</i></b></span><br />
<span lang="ES" style="mso-ansi-language: ES;"><br /></span><b style="mso-bidi-font-weight: normal;"><span lang="ES" style="mso-ansi-language: ES;">Muy probablemente, el Mediterráneo se separará del Océano, se evaporará de nuevo y acabará convertido en una gran cordillera. Australia acabará empotrada
contra</span></b> <b style="mso-bidi-font-weight: normal;"><span lang="ES" style="mso-ansi-language: ES;">China. En la Tierra habrá de nuevo un único supercontinente.</span></b></div>
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A corto plazo
(geológicamente eso son algunos miles de años), la forma de los continentes
varía debido a los cambios del nivel del mar. La acumulación del agua en los
polos debido a las glaciaciones deja expuesto el fondo marino menos profundo en
el resto del planeta. El último de estos descensos del nivel del mar fue de 120
metros y ocurrió hace veinte mil años, pudiéndose entonces caminar entre Gran
Bretaña y la Europa continental o entre Asia y las grandes islas del sudeste (Indonesia,
Sumatra, Java) o entre Asia y América por el actual estrecho de Bering. Estos cambios geográficos permitieron la colonización de todo el planeta por del Homo Sapiens.</div>
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<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-9zxGBDyXY8k/W-zLAzzAX0I/AAAAAAABA74/qK0DfvkLcIw-QIE6Ux5DaOKMSY6v_xmWACLcBGAs/s1600/Sin%2Bti%25CC%2581tulo.png" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="296" data-original-width="409" height="231" src="https://2.bp.blogspot.com/-9zxGBDyXY8k/W-zLAzzAX0I/AAAAAAABA74/qK0DfvkLcIw-QIE6Ux5DaOKMSY6v_xmWACLcBGAs/s320/Sin%2Bti%25CC%2581tulo.png" width="320" /></a></td></tr>
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<b style="mso-bidi-font-weight: normal;"><span lang="ES" style="font-size: 10.5pt; mso-ansi-language: ES;">Parte del actual fondo marino de la Tierra fue expuesto durante la última glaciación, aumentando la superficie expuesta de los continentes, como muestran las imágenes. [Datos: NOAA]</span></b></div>
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<a href="https://4.bp.blogspot.com/-wl7fGLk4_64/W-zLAiJMrZI/AAAAAAABA70/wLYhqWV7l_IPVZ5HjMTzN1ZZZDY6UV2jQCLcBGAs/s1600/Sin%2Bti%25CC%2581tulo2.png" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="296" data-original-width="474" height="199" src="https://4.bp.blogspot.com/-wl7fGLk4_64/W-zLAiJMrZI/AAAAAAABA70/wLYhqWV7l_IPVZ5HjMTzN1ZZZDY6UV2jQCLcBGAs/s320/Sin%2Bti%25CC%2581tulo2.png" width="320" /></a><br />
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<span lang="ES" style="mso-ansi-language: ES;">El actual aumento
del nivel del mar de 3 milímetros por año, causado principalmente por el cambio
climático ligado a la actividad humana, ya amenaza con inundar amplias zonas
como Bangladesh o Nueva Orleans y se teme que cause </span><span lang="EN-US"><a href="https://www.nature.com/articles/nclimate3271"><span lang="ES" style="mso-ansi-language: ES;">grandes migraciones </span></a></span><span lang="ES" style="mso-ansi-language: ES;"><span style="mso-spacerun: yes;"> </span>en
las próximas décadas.<o:p></o:p></span></div>
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<span lang="ES" style="mso-ansi-language: ES;">A más largo plazo,
en los próximos millones de años, el fenómeno principal que determina los cambios de los continentes es la tectónica de placas. La capa externa y rígida de la Tierra (litosfera) está dividida en
una decena de placas que se mueven sobre el magma fluido en distintas
direcciones. África se aproxima a Europa a una velocidad de entre 4 y 25
milímetros cada año. En pocos millones de años el Estrecho de Gibraltar se
cerrará y el Mar Mediterráneo perderá el suministro de agua del Atlántico,
evaporándose y depositando una capa de sal de cientos de metros de espesor, rodeada de un inmenso desierto. </span></div>
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<span lang="ES" style="mso-ansi-language: ES;">20
millones de años después, el acercamiento entre África y Eurasia aplastará en
medio al Mediterráneo y lo convertirá en una enorme cadena montañosa desde
Cádiz a Arabia. Para entonces, Australia habrá sido arrastrada hacia el
continente asiático debido al hundimiento (<i style="mso-bidi-font-style: normal;">subducción</i>)
de la densa litosfera del Pacífico.</span></div>
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<tr><td style="text-align: center;"><a href="https://3.bp.blogspot.com/-2x1AM731CGs/W-zLx7CuvGI/AAAAAAABA8E/fAoObHZ4dSc660kfu2Ga6KsYtkThd2a8gCLcBGAs/s1600/Sin%2Bti%25CC%2581tulo.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="627" data-original-width="940" height="424" src="https://3.bp.blogspot.com/-2x1AM731CGs/W-zLx7CuvGI/AAAAAAABA8E/fAoObHZ4dSc660kfu2Ga6KsYtkThd2a8gCLcBGAs/s640/Sin%2Bti%25CC%2581tulo.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b style="font-size: medium; text-align: start;"><span lang="ES" style="font-size: 10.5pt; mso-ansi-language: ES;">Los continentes dentro de 50 millones de años según C.R. Scotese. http://www.scotese.com/</span></b></td></tr>
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La relevancia científica de estas predicciones es cuestionable, puesto que nadie va a poder comprobar su validez. Pero su belleza es indiscutible. Os dejo con este vídeo de C.R. Scotesse con los movimientos de placas tectónicas previstos para el futuro: </div>
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<span style="font-size: x-small;">Más información:</span></div>
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<span lang="ES" style="font-size: x-small; mso-ansi-language: ES;"><o:p>Original article about sea level changes and future migrations:</o:p></span></div>
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<span style="font-size: x-small;">https://www.nature.com/articles/nclimate3271</span><br />
<span style="font-size: x-small;"><br /></span></div>
Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com2tag:blogger.com,1999:blog-4996769537501094384.post-7967151529168530032018-07-07T22:10:00.000+02:002019-07-27T19:27:29.660+02:00Megainundaciones: ¿cuánto contribuyen al relieve terrestre?<span style="font-size: xx-small;">[Este post fue inicialmente escrito para la <a href="https://naukas.com/2018/07/12/megainundaciones-cuanto-contribuyen-al-relieve-terrestre-2/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+naukas+%28Naukas%29">revista de divulgación Naukas</a> y está relacionado con dos artículos científicos que hemos publicado recientemente (ver lista de referencias al final)]</span><br />
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Antes de la geología estaba el mito. Catástrofes épicas que explicaban porqué vemos fósiles de seres que no existen y porqué otros fósiles que reconocemos como seres marinos se encuentran en lo alto de las montañas. Esa visión catastrofista tenía respuesta para todo y se convirtió en parte fundamental de las religiones.<br />
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Pero cuando la revolución copernicana emergió del renacimiento, esa forma mágica y sobrenatural de entender el mundo dejó de bastar y surgió la necesidad de comprender en base a lo cotidiano, a lo empírico, con un alcance universal.<br />
Nicolas Steno desarrolló en 1669 los <a href="https://en.wikipedia.org/wiki/Nicolas_Steno#Geology_and_stratigraphy">principios de la estratigrafía</a> y un siglo después, el concepto <i>trending</i> de la época, el <i><a href="https://es.wikipedia.org/wiki/Uniformismo">uniformismo</a>,</i> fue incorporado a la geología bajo el nombre de <i><b>gradualismo</b></i> (Hutton, 1785)<i>.</i> Postulaba que las rocas y sus fósiles han sido formadas por los mismos procesos que observamos hoy en día, actuando lentamente, a velocidades similares a las actuales y durante larguísimos periodos de tiempo que desafiaban los dogmas religiosos.<br />
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Así pues, desde los <a href="http://retosterricolas.blogspot.com/2013/10/the-early-history-of-geoscience.html">orígenes de la geología</a> como una ciencia moderna más, el relieve de la Tierra ha sido visto como el resultado de lentos procesos: la erosión de los ríos; el movimiento y la deformación de los continentes. La ciencia geológica se fraguó por tanto en contraposición con aquella visión religiosa de grandes cataclismos. <a href="https://retosterricolas.blogspot.com/2012/02/megafloods-gradualism-and-birth-of.html">El gradualismo se convirtió en uno de sus más sólidos mantras científicos</a>.<br />
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Y todo fue muy bien durante 150 años hasta que, a principios del siglo pasado, un hombre se atrevió a blasfemar contra ese paradigma tan lentamente consolidado. Se llamaba J. Harlen Bretz.<br />
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<a href="https://4.bp.blogspot.com/-WfFC0IoJvj4/W0kWJVThbvI/AAAAAAAA8Ec/ql6qZsGmqBkWODKS5na9DI6hgwD_juOXwCLcBGAs/s1600/Bretz.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="700" data-original-width="664" height="320" src="https://4.bp.blogspot.com/-WfFC0IoJvj4/W0kWJVThbvI/AAAAAAAA8Ec/ql6qZsGmqBkWODKS5na9DI6hgwD_juOXwCLcBGAs/s320/Bretz.jpg" width="303" /></a></div>
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J. Harlen Bretz, 1949.</div>
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Bretz estudió el paisaje de la región de los Scablands, que ocupan buena parte del estado de Washington (EEUU). Encontró formas erosivas y acumulaciones de sedimento que sólo podía explicar invocando <i>megainundaciones</i> de una magnitud sin precedentes, hoy bien conocidas como las <a href="http://retosterricolas.blogspot.com/2012/02/megafloods-gradualism-and-birth-of.html">Inundaciones de Missoula</a>. Inundaciones descomunales ocurridas hace unos 17.000 años y que debían haber excedido en varios órdenes de magnitud las inundaciones que habitualmente, en base a nuestra corta experiencia histórica, consideramos <i>catastróficas</i>.<br />
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Pese a su conocido carácter terco, <b>Bretz tardó cuatro décadas</b> en convencer a la comunidad geomorfológica de que su interpretación, por excéntrica que pareciera, era la más sencilla. Se estaba enfrentando a siglos de lucha entre las concepciones geológica y religiosa del mundo, y muchos de sus colegas le consideraban un lunático defensor de la segunda. A su manera, Bretz se convirtió en un <b><i>hereje</i> de la ciencia</b>.<br />
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Todavía hoy en día, la noción de que las inundaciones más excepcionales también contribuyen al modelado del paisaje sigue siendo vastamente ignorada.<br />
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Pero ¿cuáles son estos fenómenos? ¿Cuanto contribuyen? ¿Cómo de excepcionales son?<br />
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Uno de los mecanismos responsables de estas megainundaciones es el desbordamiento de grandes lagos. El fenómeno es idéntico al que ocurre cuando una <a href="http://retosterricolas.blogspot.com.es/2010/05/hunza-landslide-and-possible-outburst.html">avalancha de roca bloquea el valle de un río</a> de montaña y forma un nuevo lago: Cuando el lago rebosa, aunque inicialmente lo haga muy lentamente, la erosión puede desencadenar un aumento exponencial del flujo de agua, hasta producir caudales enormes de agua que pueden causar importantes pérdidas humanas y económicas río abajo.<br />
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Para emular el proceso, en este experimento en el USGS de Oregón formamos un pequeño lago tras una barrera de arena compactada:<br />
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<span style="font-family: "arial" , "helvetica" , sans-serif; font-size: xx-small;"><b>Experimento de desbordamiento de un lago </b></span></div>
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<span style="font-family: "arial" , "helvetica" , sans-serif; font-size: xx-small;"><b>de 23 m2 barrado por arena compactada.</b></span></div>
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La erosión que produce el agua en el canal de salida se retroalimenta con el flujo de agua que dicho canal permite evacuar:<br />
<div>
<br /></div>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td><a href="http://4.bp.blogspot.com/-Ae-FPyIQMYg/UegJue5VABI/AAAAAAAAVS4/rMUgGmwak8s/s1600/cartoon+conceptual+desbordamiento+overtopping.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="186" src="https://4.bp.blogspot.com/-Ae-FPyIQMYg/UegJue5VABI/AAAAAAAAVS4/rMUgGmwak8s/s400/cartoon+conceptual+desbordamiento+overtopping.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.7273px;"><b>Esquema de la retroalimentación entre flujo de agua </b><b>y erosión del </b><br />
<b>desaguadero de un lago de montaña. Cuanta más erosión, más caudal </b><br />
<b>de agua. Cuanto más caudal, más rápida la erosión.</b></td></tr>
</tbody></table>
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<br />
<br />
Los datos disponibles sobre el pico de caudal que se alcanza en desbordamientos históricos permiten estimar empíricamente el riesgo en escenarios naturales. Los resultados son bastante intuitivos: cuanto mayor es el tamaño del lago y más débil es la barrera, más intenso será el pico de descarga de agua tras el desbordamiento. Pero estos resultados apenas permiten predecir la intensidad de las inundaciones porque las heterogeneidades de la barrera pueden ser tan determinantes como los factores anteriores: Una sola roca de gran tamaño, por ejemplo, puede retrasar la erosión del desaguadero y evitar la inundación. <br />
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<span style="font-family: "arial" , "helvetica" , sans-serif; font-size: xx-small;"><b>Este sigue siendo el video que mejor muestra </b></span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif; font-size: xx-small;"><b>la fuerza a la que puede conducir un desbordamiento </b></span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif; font-size: xx-small;"><b>(en este caso el mar desborda sobre una mina a cielo </b></span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif; font-size: xx-small;"><b>abierto). </b><b>Se trata de la <a href="http://en.wikipedia.org/wiki/Pantai_Remis_landslide">Pantai Remis landslide</a>, </b></span><br />
<span style="font-family: "arial" , "helvetica" , sans-serif; font-size: xx-small;"><b>que ocurrió en Malasia en 1993.</b></span></div>
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<b><span style="font-family: "arial" , "helvetica" , sans-serif; font-size: xx-small;">Time-lapse del desbordamiento de una presa de tierra </span></b></div>
<div style="margin: 0px;">
<b><span style="font-family: "arial" , "helvetica" , sans-serif; font-size: xx-small;">en Oregón (Marmot Dam, Sandy River, Oregon)</span></b></div>
</div>
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Sin embargo, las inundaciones por desbordamiento han sido mucho mayores en el pasado geológico que esos casos históricos, y pese a ello han permanecido mayormente ignoradas.<br />
<br />
En un artículo reciente (la referencia está al final de este post, <span style="font-size: xx-small;">Abril et al., 2018</span>) hemos modelizado en 3D el flujo de la mayor megainundación de entre las mejor documentadas: El desbordamiento del <a href="http://retosterricolas.blogspot.com/2012/09/see-lithosphere-moving-up-and-down.html">Lago Bonneville</a> durante el Pleistoceno, hace unos 15.000 años:<br />
<blockquote class="twitter-tweet" data-lang="en">
<div dir="ltr" lang="en">
Our last publication is already online! - As Lake Bonneville overtopped... <br />
Fluid Dynamics simulations of the Late Pleistocene Lake Bonneville Flood <a href="https://t.co/JKTIuptsfl">https://t.co/JKTIuptsfl</a> <a href="https://t.co/xsSd8BPwer">pic.twitter.com/xsSd8BPwer</a></div>
— ∆(Garcia-Castellanos) (@danigeos) <a href="https://twitter.com/danigeos/status/992886144806408193?ref_src=twsrc%5Etfw">May 5, 2018</a></blockquote>
<script async="" charset="utf-8" src="https://platform.twitter.com/widgets.js"></script>
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<br />
El desbordamiento del Lago Bonneville <span style="font-size: xx-small;">(Jarrett & Malde, 1987)</span> tuvo lugar al sobrepasar su nivel la barrera topográfica formada por un delta fluvial (sedimento consolidado) a unos 1500 m sobre el nivel del mar. Alcanzó un caudal de agua de un millón de metros cúbicos por segundo: <b>el agua que cabe en el Camp Nou, cada 2 segundos</b>. Estos posts dan algo más de contexto: <a href="https://retosterricolas.blogspot.com/2012/07/large-pleistocene-floods-along-columbia.html">[1]</a>, <a href="http://retosterricolas.blogspot.com/2012/09/see-lithosphere-moving-up-and-down.html">[2]</a>.<br />
<br />
Desde las primeras exploraciones de Gilbert en el <a href="http://retosterricolas.blogspot.com.es/2012/09/see-lithosphere-moving-up-and-down.html">Lago Bonneville</a> (Gilbert, 1890) y las de Bretz, se han acumulado numerosas evidencias de que el desbordamiento de muchos otros lagos ha desencadenado inundaciones de mayor intensidad que las registradas históricamente, que alcanzan los 10^5 m3/s (la mitad del débito medio actual del río Amazonas), como ocurrió p.e. tras el bloqueo del río Yigong por una avalancha en 2000.<br />
<br />
Sin embargo, la mayor inundación podría haber sido la <a href="https://es.wikipedia.org/wiki/Inundaci%C3%B3n_zancliense">Inundación Zancliense</a>, que puso fin a la Crisis de Salinidad Messiniense hace 5.3 millones de años <span style="font-size: xx-small;">(e.g., Blanc, 2006; <a href="https://www.nature.com/articles/nature08555">Garcia-Castellanos et al., 2009</a>)</span>, tras el desbordamiento del Océano Atlántico sobre un Mediterráneo parcialmente desecado. El consenso en este caso no es completo, pero de confirmarse podría haber causado caudales de hasta 100 millones de metros cúbicos por segundo. La compilación más completa de este tipo de eventos puede encontrarse en el material suplementario de nuestro artículo <span style="font-size: xx-small;">(Garcia-Castellanos & O'Connor, 2018, </span><i><span style="font-size: xx-small;">Scientific Reports</span></i><span style="font-size: xx-small;">)</span> referencia más abajo).<br />
<br />
Lo que proponemos en ese segundo artículo es un nuevo método para medir la erodabilidad de la superficie de la Tierra, es decir la facilidad con la que ésta es modificada por la acción mecánica del agua. Y ese método utiliza precisamente la erosión producida en todas estas megainundaciones ocurridas en el pasado reciente de la Tierra.<br />
<br />
El método consiste en resolver con un código escrito en C un sistema de ecuaciones que calcula la erosión producida por el agua (modelos desarrollados por la comunidad geomorfológica global) y el caudal de agua que se produce en el desaguadero de un lago (relaciones hidrológicas relativamente sencillas). Simulando con este programa el desbordamiento de cada lago buscamos el valor de la erodabilidad de la presa natural correspondiente que permite reproducir los datos del caudal de agua. Estos datos de caudal han sido derivados a lo largo de décadas en numerosos estudios de geomorfología de campo en lagos del Pleistoceno <span style="font-size: xx-small;">(O'Connor & Beebee, 2009)</span>.<br />
<br />
Esos estudios previos, junto con experimentos realizados con presas de tierra o arena, nos permiten disponer de datos sobre la descarga de agua y la erosión que se extienden a lo largo de 10 órdenes de magnitud en términos de volumen de agua total evacuada. La figura muestra los escenarios naturales mejor estudiados (los de volúmenes más importantes).</div>
<div>
<br />
<a href="http://www.blogger.com/blogger.g?blogID=4996769537501094384" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"></a><a beebee="" connor="" data.png="" flood="" href="http://2.bp.blogspot.com/-RCCRsirV6K8/UegJOq9CwqI/AAAAAAAAVSo/QR2BxO87hOw/s1600/O" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img beebee="" border="0" connor="" data.png="" flood="" height="300" src="https://2.bp.blogspot.com/-RCCRsirV6K8/UegJOq9CwqI/AAAAAAAAVSo/QR2BxO87hOw/s400/O" width="400" /></a><b><span style="font-size: x-small;">Datos sobre inundaciones debidas al desbordamiento de lagos naturales, compilados por O’Connor & Beebee (2010). Cada punto es una inundación indicando la descarga máxima de agua frente al volumen total de agua del lago. Los datos se extienden a 10 órdenes de magnitud en términos de volumen. </span></b></div>
<div>
<br />
<br />
<br />
<br />
Estos datos han servido para estimar el riesgo en escenarios naturales, aunque con muy poca precisión, para decidir el desalojo de valles fluviales cuando un río es bloqueado por una avalancha de roca, como ocurrió en el <a href="http://retosterricolas.blogspot.com.es/2010/06/la-presa-de-attabad-ya-vierte-casi.html">río Hunza</a> (sin consecuencias) o en el desbordamiento e inundación en 1963 del Lago Issyk.</div>
<div>
<br />
A nosotros, los datos de caudal nos han servido para cuantificar mejor a qué velocidad erosiona el agua el relieve del planeta. La esperanza es que en un futuro seamos capaces de predecir mejor la erosión, y concretamente, la peligrosidad de lagos a punto de ser desbordados.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://3.bp.blogspot.com/-9Xt_tWGKQWQ/W0DzxZi9UFI/AAAAAAAA8CI/fwksEFMHmAYO4XK5VBGUCeAAVfBkQmB2QCLcBGAs/s1600/Garcia-Castellanos%252C%2BO%2527Connor%2B-%2Bfigures%2B2.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1413" data-original-width="1600" height="563" src="https://3.bp.blogspot.com/-9Xt_tWGKQWQ/W0DzxZi9UFI/AAAAAAAA8CI/fwksEFMHmAYO4XK5VBGUCeAAVfBkQmB2QCLcBGAs/s640/Garcia-Castellanos%252C%2BO%2527Connor%2B-%2Bfigures%2B2.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b>Resultado de la simulación numérica de dos inundaciones (izquierda: <br />Lago Bonneville; derecha, experimento del vídeo mostrado más arriba).<br />Se muestra la evolución de varios parámetros como el caudal de agua Q <br />o el nivel del agua z_l. La erodabilidad necesitada para reproducir los <br />datos de caudal (círculos) es mucho menor en el experimento que en<br />Bonneville.</b></td></tr>
</tbody></table>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-V6X5SzP3u7o/W0D09AjG47I/AAAAAAAA8CU/4XeKj3xliIobFanOULHI1KDKpjgiEeE6gCLcBGAs/s1600/Garcia-Castellanos%252C%2BO%2527Connor%2B-%2Bfigures%2B3%2Bcrop.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1234" data-original-width="1060" height="400" src="https://4.bp.blogspot.com/-V6X5SzP3u7o/W0D09AjG47I/AAAAAAAA8CU/4XeKj3xliIobFanOULHI1KDKpjgiEeE6gCLcBGAs/s400/Garcia-Castellanos%252C%2BO%2527Connor%2B-%2Bfigures%2B3%2Bcrop.png" width="342" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b>Relación encontrada entre la erodabilidad del </b><b>desaguadero </b><br />
<b>de los lagos estudiados y el tipo </b><b>de roca. La correlación </b><br />
<b>demuestra que el método permite </b><b>medir la erodabilidad.</b></td></tr>
</tbody></table>
<br />
Los resultados indican no sólo que los desbordamientos catastróficos, pese a ser poco frecuentes, pueden cambiar significativamente el relieve, sino que además será importante incluir la periodicidad de las inundaciones (meteorológicas o no) en los futuros modelos, porque su distribución frecuencia-magnitud es también crucial en la evolución del relieve terrestre.<br />
<br />
[M<a href="https://www.youtube.com/watch?v=tyhHjDLwHlI">y conference on this subject at the PAGES meeting, 2017</a>]<br />
<div>
<br />
<br /></div>
<br />
<b>Referencias:</b><br />
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<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Body Text 3"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Body Text Indent 2"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Body Text Indent 3"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Block Text"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Hyperlink"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="FollowedHyperlink"/>
<w:LsdException Locked="false" Priority="22" QFormat="true" Name="Strong"/>
<w:LsdException Locked="false" Priority="20" QFormat="true" Name="Emphasis"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Document Map"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Plain Text"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="E-mail Signature"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="HTML Top of Form"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="HTML Bottom of Form"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Normal (Web)"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="HTML Acronym"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="HTML Address"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="HTML Cite"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="HTML Code"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="HTML Definition"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="HTML Keyboard"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="HTML Preformatted"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="HTML Sample"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="HTML Typewriter"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="HTML Variable"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Normal Table"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="annotation subject"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="No List"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Outline List 1"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Outline List 2"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Outline List 3"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Simple 1"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Simple 2"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Simple 3"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Classic 1"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Classic 2"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Classic 3"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Classic 4"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Colorful 1"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Colorful 2"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Colorful 3"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Columns 1"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Columns 2"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Columns 3"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Columns 4"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Columns 5"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Grid 1"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Grid 2"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Grid 3"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Grid 4"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Grid 5"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Grid 6"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Grid 7"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Grid 8"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table List 1"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table List 2"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table List 3"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table List 4"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table List 5"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table List 6"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table List 7"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table List 8"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table 3D effects 1"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table 3D effects 2"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table 3D effects 3"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Contemporary"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Elegant"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Professional"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Subtle 1"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Subtle 2"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Web 1"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Web 2"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Web 3"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Balloon Text"/>
<w:LsdException Locked="false" Priority="39" Name="Table Grid"/>
<w:LsdException Locked="false" SemiHidden="true" UnhideWhenUsed="true"
Name="Table Theme"/>
<w:LsdException Locked="false" SemiHidden="true" Name="Placeholder Text"/>
<w:LsdException Locked="false" Priority="1" QFormat="true" Name="No Spacing"/>
<w:LsdException Locked="false" Priority="60" Name="Light Shading"/>
<w:LsdException Locked="false" Priority="61" Name="Light List"/>
<w:LsdException Locked="false" Priority="62" Name="Light Grid"/>
<w:LsdException Locked="false" Priority="63" Name="Medium Shading 1"/>
<w:LsdException Locked="false" Priority="64" Name="Medium Shading 2"/>
<w:LsdException Locked="false" Priority="65" Name="Medium List 1"/>
<w:LsdException Locked="false" Priority="66" Name="Medium List 2"/>
<w:LsdException Locked="false" Priority="67" Name="Medium Grid 1"/>
<w:LsdException Locked="false" Priority="68" Name="Medium Grid 2"/>
<w:LsdException Locked="false" Priority="69" Name="Medium Grid 3"/>
<w:LsdException Locked="false" Priority="70" Name="Dark List"/>
<w:LsdException Locked="false" Priority="71" Name="Colorful Shading"/>
<w:LsdException Locked="false" Priority="72" Name="Colorful List"/>
<w:LsdException Locked="false" Priority="73" Name="Colorful Grid"/>
<w:LsdException Locked="false" Priority="60" Name="Light Shading Accent 1"/>
<w:LsdException Locked="false" Priority="61" Name="Light List Accent 1"/>
<w:LsdException Locked="false" Priority="62" Name="Light Grid Accent 1"/>
<w:LsdException Locked="false" Priority="63" Name="Medium Shading 1 Accent 1"/>
<w:LsdException Locked="false" Priority="64" Name="Medium Shading 2 Accent 1"/>
<w:LsdException Locked="false" Priority="65" Name="Medium List 1 Accent 1"/>
<w:LsdException Locked="false" SemiHidden="true" Name="Revision"/>
<w:LsdException Locked="false" Priority="34" QFormat="true"
Name="List Paragraph"/>
<w:LsdException Locked="false" Priority="29" QFormat="true" Name="Quote"/>
<w:LsdException Locked="false" Priority="30" QFormat="true"
Name="Intense Quote"/>
<w:LsdException Locked="false" Priority="66" Name="Medium List 2 Accent 1"/>
<w:LsdException Locked="false" Priority="67" Name="Medium Grid 1 Accent 1"/>
<w:LsdException Locked="false" Priority="68" Name="Medium Grid 2 Accent 1"/>
<w:LsdException Locked="false" Priority="69" Name="Medium Grid 3 Accent 1"/>
<w:LsdException Locked="false" Priority="70" Name="Dark List Accent 1"/>
<w:LsdException Locked="false" Priority="71" Name="Colorful Shading Accent 1"/>
<w:LsdException Locked="false" Priority="72" Name="Colorful List Accent 1"/>
<w:LsdException Locked="false" Priority="73" Name="Colorful Grid Accent 1"/>
<w:LsdException Locked="false" Priority="60" Name="Light Shading Accent 2"/>
<w:LsdException Locked="false" Priority="61" Name="Light List Accent 2"/>
<w:LsdException Locked="false" Priority="62" Name="Light Grid Accent 2"/>
<w:LsdException Locked="false" Priority="63" Name="Medium Shading 1 Accent 2"/>
<w:LsdException Locked="false" Priority="64" Name="Medium Shading 2 Accent 2"/>
<w:LsdException Locked="false" Priority="65" Name="Medium List 1 Accent 2"/>
<w:LsdException Locked="false" Priority="66" Name="Medium List 2 Accent 2"/>
<w:LsdException Locked="false" Priority="67" Name="Medium Grid 1 Accent 2"/>
<w:LsdException Locked="false" Priority="68" Name="Medium Grid 2 Accent 2"/>
<w:LsdException Locked="false" Priority="69" Name="Medium Grid 3 Accent 2"/>
<w:LsdException Locked="false" Priority="70" Name="Dark List Accent 2"/>
<w:LsdException Locked="false" Priority="71" Name="Colorful Shading Accent 2"/>
<w:LsdException Locked="false" Priority="72" Name="Colorful List Accent 2"/>
<w:LsdException Locked="false" Priority="73" Name="Colorful Grid Accent 2"/>
<w:LsdException Locked="false" Priority="60" Name="Light Shading Accent 3"/>
<w:LsdException Locked="false" Priority="61" Name="Light List Accent 3"/>
<w:LsdException Locked="false" Priority="62" Name="Light Grid Accent 3"/>
<w:LsdException Locked="false" Priority="63" Name="Medium Shading 1 Accent 3"/>
<w:LsdException Locked="false" Priority="64" Name="Medium Shading 2 Accent 3"/>
<w:LsdException Locked="false" Priority="65" Name="Medium List 1 Accent 3"/>
<w:LsdException Locked="false" Priority="66" Name="Medium List 2 Accent 3"/>
<w:LsdException Locked="false" Priority="67" Name="Medium Grid 1 Accent 3"/>
<w:LsdException Locked="false" Priority="68" Name="Medium Grid 2 Accent 3"/>
<w:LsdException Locked="false" Priority="69" Name="Medium Grid 3 Accent 3"/>
<w:LsdException Locked="false" Priority="70" Name="Dark List Accent 3"/>
<w:LsdException Locked="false" Priority="71" Name="Colorful Shading Accent 3"/>
<w:LsdException Locked="false" Priority="72" Name="Colorful List Accent 3"/>
<w:LsdException Locked="false" Priority="73" Name="Colorful Grid Accent 3"/>
<w:LsdException Locked="false" Priority="60" Name="Light Shading Accent 4"/>
<w:LsdException Locked="false" Priority="61" Name="Light List Accent 4"/>
<w:LsdException Locked="false" Priority="62" Name="Light Grid Accent 4"/>
<w:LsdException Locked="false" Priority="63" Name="Medium Shading 1 Accent 4"/>
<w:LsdException Locked="false" Priority="64" Name="Medium Shading 2 Accent 4"/>
<w:LsdException Locked="false" Priority="65" Name="Medium List 1 Accent 4"/>
<w:LsdException Locked="false" Priority="66" Name="Medium List 2 Accent 4"/>
<w:LsdException Locked="false" Priority="67" Name="Medium Grid 1 Accent 4"/>
<w:LsdException Locked="false" Priority="68" Name="Medium Grid 2 Accent 4"/>
<w:LsdException Locked="false" Priority="69" Name="Medium Grid 3 Accent 4"/>
<w:LsdException Locked="false" Priority="70" Name="Dark List Accent 4"/>
<w:LsdException Locked="false" Priority="71" Name="Colorful Shading Accent 4"/>
<w:LsdException Locked="false" Priority="72" Name="Colorful List Accent 4"/>
<w:LsdException Locked="false" Priority="73" Name="Colorful Grid Accent 4"/>
<w:LsdException Locked="false" Priority="60" Name="Light Shading Accent 5"/>
<w:LsdException Locked="false" Priority="61" Name="Light List Accent 5"/>
<w:LsdException Locked="false" Priority="62" Name="Light Grid Accent 5"/>
<w:LsdException Locked="false" Priority="63" Name="Medium Shading 1 Accent 5"/>
<w:LsdException Locked="false" Priority="64" Name="Medium Shading 2 Accent 5"/>
<w:LsdException Locked="false" Priority="65" Name="Medium List 1 Accent 5"/>
<w:LsdException Locked="false" Priority="66" Name="Medium List 2 Accent 5"/>
<w:LsdException Locked="false" Priority="67" Name="Medium Grid 1 Accent 5"/>
<w:LsdException Locked="false" Priority="68" Name="Medium Grid 2 Accent 5"/>
<w:LsdException Locked="false" Priority="69" Name="Medium Grid 3 Accent 5"/>
<w:LsdException Locked="false" Priority="70" Name="Dark List Accent 5"/>
<w:LsdException Locked="false" Priority="71" Name="Colorful Shading Accent 5"/>
<w:LsdException Locked="false" Priority="72" Name="Colorful List Accent 5"/>
<w:LsdException Locked="false" Priority="73" Name="Colorful Grid Accent 5"/>
<w:LsdException Locked="false" Priority="60" Name="Light Shading Accent 6"/>
<w:LsdException Locked="false" Priority="61" Name="Light List Accent 6"/>
<w:LsdException Locked="false" Priority="62" Name="Light Grid Accent 6"/>
<w:LsdException Locked="false" Priority="63" Name="Medium Shading 1 Accent 6"/>
<w:LsdException Locked="false" Priority="64" Name="Medium Shading 2 Accent 6"/>
<w:LsdException Locked="false" Priority="65" Name="Medium List 1 Accent 6"/>
<w:LsdException Locked="false" Priority="66" Name="Medium List 2 Accent 6"/>
<w:LsdException Locked="false" Priority="67" Name="Medium Grid 1 Accent 6"/>
<w:LsdException Locked="false" Priority="68" Name="Medium Grid 2 Accent 6"/>
<w:LsdException Locked="false" Priority="69" Name="Medium Grid 3 Accent 6"/>
<w:LsdException Locked="false" Priority="70" Name="Dark List Accent 6"/>
<w:LsdException Locked="false" Priority="71" Name="Colorful Shading Accent 6"/>
<w:LsdException Locked="false" Priority="72" Name="Colorful List Accent 6"/>
<w:LsdException Locked="false" Priority="73" Name="Colorful Grid Accent 6"/>
<w:LsdException Locked="false" Priority="19" QFormat="true"
Name="Subtle Emphasis"/>
<w:LsdException Locked="false" Priority="21" QFormat="true"
Name="Intense Emphasis"/>
<w:LsdException Locked="false" Priority="31" QFormat="true"
Name="Subtle Reference"/>
<w:LsdException Locked="false" Priority="32" QFormat="true"
Name="Intense Reference"/>
<w:LsdException Locked="false" Priority="33" QFormat="true" Name="Book Title"/>
<w:LsdException Locked="false" Priority="37" SemiHidden="true"
UnhideWhenUsed="true" Name="Bibliography"/>
<w:LsdException Locked="false" Priority="39" SemiHidden="true"
UnhideWhenUsed="true" QFormat="true" Name="TOC Heading"/>
<w:LsdException Locked="false" Priority="41" Name="Plain Table 1"/>
<w:LsdException Locked="false" Priority="42" Name="Plain Table 2"/>
<w:LsdException Locked="false" Priority="43" Name="Plain Table 3"/>
<w:LsdException Locked="false" Priority="44" Name="Plain Table 4"/>
<w:LsdException Locked="false" Priority="45" Name="Plain Table 5"/>
<w:LsdException Locked="false" Priority="40" Name="Grid Table Light"/>
<w:LsdException Locked="false" Priority="46" Name="Grid Table 1 Light"/>
<w:LsdException Locked="false" Priority="47" Name="Grid Table 2"/>
<w:LsdException Locked="false" Priority="48" Name="Grid Table 3"/>
<w:LsdException Locked="false" Priority="49" Name="Grid Table 4"/>
<w:LsdException Locked="false" Priority="50" Name="Grid Table 5 Dark"/>
<w:LsdException Locked="false" Priority="51" Name="Grid Table 6 Colorful"/>
<w:LsdException Locked="false" Priority="52" Name="Grid Table 7 Colorful"/>
<w:LsdException Locked="false" Priority="46"
Name="Grid Table 1 Light Accent 1"/>
<w:LsdException Locked="false" Priority="47" Name="Grid Table 2 Accent 1"/>
<w:LsdException Locked="false" Priority="48" Name="Grid Table 3 Accent 1"/>
<w:LsdException Locked="false" Priority="49" Name="Grid Table 4 Accent 1"/>
<w:LsdException Locked="false" Priority="50" Name="Grid Table 5 Dark Accent 1"/>
<w:LsdException Locked="false" Priority="51"
Name="Grid Table 6 Colorful Accent 1"/>
<w:LsdException Locked="false" Priority="52"
Name="Grid Table 7 Colorful Accent 1"/>
<w:LsdException Locked="false" Priority="46"
Name="Grid Table 1 Light Accent 2"/>
<w:LsdException Locked="false" Priority="47" Name="Grid Table 2 Accent 2"/>
<w:LsdException Locked="false" Priority="48" Name="Grid Table 3 Accent 2"/>
<w:LsdException Locked="false" Priority="49" Name="Grid Table 4 Accent 2"/>
<w:LsdException Locked="false" Priority="50" Name="Grid Table 5 Dark Accent 2"/>
<w:LsdException Locked="false" Priority="51"
Name="Grid Table 6 Colorful Accent 2"/>
<w:LsdException Locked="false" Priority="52"
Name="Grid Table 7 Colorful Accent 2"/>
<w:LsdException Locked="false" Priority="46"
Name="Grid Table 1 Light Accent 3"/>
<w:LsdException Locked="false" Priority="47" Name="Grid Table 2 Accent 3"/>
<w:LsdException Locked="false" Priority="48" Name="Grid Table 3 Accent 3"/>
<w:LsdException Locked="false" Priority="49" Name="Grid Table 4 Accent 3"/>
<w:LsdException Locked="false" Priority="50" Name="Grid Table 5 Dark Accent 3"/>
<w:LsdException Locked="false" Priority="51"
Name="Grid Table 6 Colorful Accent 3"/>
<w:LsdException Locked="false" Priority="52"
Name="Grid Table 7 Colorful Accent 3"/>
<w:LsdException Locked="false" Priority="46"
Name="Grid Table 1 Light Accent 4"/>
<w:LsdException Locked="false" Priority="47" Name="Grid Table 2 Accent 4"/>
<w:LsdException Locked="false" Priority="48" Name="Grid Table 3 Accent 4"/>
<w:LsdException Locked="false" Priority="49" Name="Grid Table 4 Accent 4"/>
<w:LsdException Locked="false" Priority="50" Name="Grid Table 5 Dark Accent 4"/>
<w:LsdException Locked="false" Priority="51"
Name="Grid Table 6 Colorful Accent 4"/>
<w:LsdException Locked="false" Priority="52"
Name="Grid Table 7 Colorful Accent 4"/>
<w:LsdException Locked="false" Priority="46"
Name="Grid Table 1 Light Accent 5"/>
<w:LsdException Locked="false" Priority="47" Name="Grid Table 2 Accent 5"/>
<w:LsdException Locked="false" Priority="48" Name="Grid Table 3 Accent 5"/>
<w:LsdException Locked="false" Priority="49" Name="Grid Table 4 Accent 5"/>
<w:LsdException Locked="false" Priority="50" Name="Grid Table 5 Dark Accent 5"/>
<w:LsdException Locked="false" Priority="51"
Name="Grid Table 6 Colorful Accent 5"/>
<w:LsdException Locked="false" Priority="52"
Name="Grid Table 7 Colorful Accent 5"/>
<w:LsdException Locked="false" Priority="46"
Name="Grid Table 1 Light Accent 6"/>
<w:LsdException Locked="false" Priority="47" Name="Grid Table 2 Accent 6"/>
<w:LsdException Locked="false" Priority="48" Name="Grid Table 3 Accent 6"/>
<w:LsdException Locked="false" Priority="49" Name="Grid Table 4 Accent 6"/>
<w:LsdException Locked="false" Priority="50" Name="Grid Table 5 Dark Accent 6"/>
<w:LsdException Locked="false" Priority="51"
Name="Grid Table 6 Colorful Accent 6"/>
<w:LsdException Locked="false" Priority="52"
Name="Grid Table 7 Colorful Accent 6"/>
<w:LsdException Locked="false" Priority="46" Name="List Table 1 Light"/>
<w:LsdException Locked="false" Priority="47" Name="List Table 2"/>
<w:LsdException Locked="false" Priority="48" Name="List Table 3"/>
<w:LsdException Locked="false" Priority="49" Name="List Table 4"/>
<w:LsdException Locked="false" Priority="50" Name="List Table 5 Dark"/>
<w:LsdException Locked="false" Priority="51" Name="List Table 6 Colorful"/>
<w:LsdException Locked="false" Priority="52" Name="List Table 7 Colorful"/>
<w:LsdException Locked="false" Priority="46"
Name="List Table 1 Light Accent 1"/>
<w:LsdException Locked="false" Priority="47" Name="List Table 2 Accent 1"/>
<w:LsdException Locked="false" Priority="48" Name="List Table 3 Accent 1"/>
<w:LsdException Locked="false" Priority="49" Name="List Table 4 Accent 1"/>
<w:LsdException Locked="false" Priority="50" Name="List Table 5 Dark Accent 1"/>
<w:LsdException Locked="false" Priority="51"
Name="List Table 6 Colorful Accent 1"/>
<w:LsdException Locked="false" Priority="52"
Name="List Table 7 Colorful Accent 1"/>
<w:LsdException Locked="false" Priority="46"
Name="List Table 1 Light Accent 2"/>
<w:LsdException Locked="false" Priority="47" Name="List Table 2 Accent 2"/>
<w:LsdException Locked="false" Priority="48" Name="List Table 3 Accent 2"/>
<w:LsdException Locked="false" Priority="49" Name="List Table 4 Accent 2"/>
<w:LsdException Locked="false" Priority="50" Name="List Table 5 Dark Accent 2"/>
<w:LsdException Locked="false" Priority="51"
Name="List Table 6 Colorful Accent 2"/>
<w:LsdException Locked="false" Priority="52"
Name="List Table 7 Colorful Accent 2"/>
<w:LsdException Locked="false" Priority="46"
Name="List Table 1 Light Accent 3"/>
<w:LsdException Locked="false" Priority="47" Name="List Table 2 Accent 3"/>
<w:LsdException Locked="false" Priority="48" Name="List Table 3 Accent 3"/>
<w:LsdException Locked="false" Priority="49" Name="List Table 4 Accent 3"/>
<w:LsdException Locked="false" Priority="50" Name="List Table 5 Dark Accent 3"/>
<w:LsdException Locked="false" Priority="51"
Name="List Table 6 Colorful Accent 3"/>
<w:LsdException Locked="false" Priority="52"
Name="List Table 7 Colorful Accent 3"/>
<w:LsdException Locked="false" Priority="46"
Name="List Table 1 Light Accent 4"/>
<w:LsdException Locked="false" Priority="47" Name="List Table 2 Accent 4"/>
<w:LsdException Locked="false" Priority="48" Name="List Table 3 Accent 4"/>
<w:LsdException Locked="false" Priority="49" Name="List Table 4 Accent 4"/>
<w:LsdException Locked="false" Priority="50" Name="List Table 5 Dark Accent 4"/>
<w:LsdException Locked="false" Priority="51"
Name="List Table 6 Colorful Accent 4"/>
<w:LsdException Locked="false" Priority="52"
Name="List Table 7 Colorful Accent 4"/>
<w:LsdException Locked="false" Priority="46"
Name="List Table 1 Light Accent 5"/>
<w:LsdException Locked="false" Priority="47" Name="List Table 2 Accent 5"/>
<w:LsdException Locked="false" Priority="48" Name="List Table 3 Accent 5"/>
<w:LsdException Locked="false" Priority="49" Name="List Table 4 Accent 5"/>
<w:LsdException Locked="false" Priority="50" Name="List Table 5 Dark Accent 5"/>
<w:LsdException Locked="false" Priority="51"
Name="List Table 6 Colorful Accent 5"/>
<w:LsdException Locked="false" Priority="52"
Name="List Table 7 Colorful Accent 5"/>
<w:LsdException Locked="false" Priority="46"
Name="List Table 1 Light Accent 6"/>
<w:LsdException Locked="false" Priority="47" Name="List Table 2 Accent 6"/>
<w:LsdException Locked="false" Priority="48" Name="List Table 3 Accent 6"/>
<w:LsdException Locked="false" Priority="49" Name="List Table 4 Accent 6"/>
<w:LsdException Locked="false" Priority="50" Name="List Table 5 Dark Accent 6"/>
<w:LsdException Locked="false" Priority="51"
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<ul>
<li>Garcia-Castellanos, D., J. O’Connor, 2018. Outburst floods provide erodability estimates consistent with long-term landscape evolution. Scientific Reports. 8:10573. Doi:10.1038/s41598-018-28981-y [<a href="https://www.google.com/url?q=https%3A%2F%2Fwww.nature.com%2Farticles%2Fs41598-018-28981-y.pdf&sa=D&sntz=1&usg=AFQjCNH1wZ6Ews_fdd6FMZ9r3bQHs-jjZQ">open access</a>]</li>
<li><span style="font-size: x-small; letter-spacing: -0.1pt; text-indent: -21.85pt;">Abril-Hernández, J.M., Periáñez, R., O'Connor, J.E., Garcia-Castellanos, D. Computational Fluid Dynamics simulations of the Late Pleistocene Lake Bonneville Flood (2018) </span><b style="font-size: small; letter-spacing: -0.1pt; text-indent: -21.85pt;">Journal of Hydrology</b><span style="font-size: x-small; letter-spacing: -0.1pt; text-indent: -21.85pt;">, 561, pp. 1-15. DOI: 10.1016/j.jhydrol.2018.03.065</span></li>
</ul>
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<div class="referencia">
<br /></div>
<span style="font-size: xx-small;">Gilbert, Grove Karl, 1890. Lake Bonneville. 438 p., 51 leaves of plates. Monographs of the United States Geological Survey, v. 1.</span><br />
<span style="font-size: xx-small;">O’Connor, J.E., 1993, Hydrology, Hydraulics, and Geomorphology of the Bonneville Flood: Geological Society of America Special Paper 274, 83</span></div>
Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com029482 US-91, Downey, ID 83234, USA42.34660467301002 -112.0403785910457442.299658173010023 -112.12105959104574 42.393551173010017 -111.95969759104574tag:blogger.com,1999:blog-4996769537501094384.post-543100994118353632018-03-01T09:42:00.004+01:002023-04-21T09:40:30.826+02:00New evidence for the Zanclean flooding of the Mediterranean Sea<div>
<span style="font-size: x-small;">[ICTJA-CSIC's Press Note on our own research (see open access article linked at the foot of this page)]</span></div>
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A study conducted by an international team of scientists has found new evidence supporting the hypothesis of a mega-flood occurring during the Zanclean period, in which water from the Atlantic poured back into the Mediterranean sea and ended the Messinian Salinity Crisis (MSC) 5 million years ago. The study, led by Professor Aaron Micallef from the University of Malta, has been published in the Scientific Reports journal.<br />
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<b><span face=""arial" , "helvetica" , sans-serif">Recreation of the evolution of the Messinian salinity crisis, between 6 and 5.3 milion years ago. This is one of the scenarios competing among the scientific community studying this period. Time scale (milion years per second) not to scale. [Credit: Univ. of Malta]</span></b></div>
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Using seismic profiles and borehole data from offshore eastern Sicily, researchers have identified a large body of sediments buried in the subsurface of Sicily Channel which are characterized as being "extensive" and "chaotic." They have named this mass of material Unit 2.<br />
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The study says that this huge mass of sediments is composed of materials eroded and transported by the great flow of water that flooded the Ionian Basin through the Strait of Sicily once the western basin of the Mediterranean was refilled with the contribution of water coming from the Atlantic Ocean that had poured in previously through the Strait of Gibraltar. This event is known as Zanclean megaflood.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-qARYq-sOTTc/WpVLSsUxvbI/AAAAAAAA6QI/tuhhJ8vts9IQdaTEniXJT70m2ex-Mi7OwCPcBGAYYCw/s1600/Fotos20180227_Web_02.png" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://4.bp.blogspot.com/-qARYq-sOTTc/WpVLSsUxvbI/AAAAAAAA6QI/tuhhJ8vts9IQdaTEniXJT70m2ex-Mi7OwCPcBGAYYCw/s640/Fotos20180227_Web_02.png" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span face=""arial" , "helvetica" , sans-serif"><b>Location and geometry of the "Unit 2" corresponding to the sediment body originated by the Zanclean megaflood. Source: Aaron Micallef (University of Malta)</b></span></td></tr>
</tbody></table>
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The discovered sediments have been located over a layer of salts originated previously during the partial desiccation of the Mediterranean Sea during the MSC and under another layer of common marine sediments that were deposited after the flood and during the restoration of the normal marine conditions.<br />
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"The deposits identified in our study have little reflectivity of the seismic waves, they are seismically transparent, and present a disordered internal structure of the layers which is very similar to the sediments typically originated in catastrophic floods," explains Daniel García-Castellanos, co-author of the study and researcher from Barcelona's Institute of Earth Sciences Jaume Almera of the CSIC (ICTJA-CSIC).<br />
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The study indicates that the sedimentary body found next to the base of the Malta Escarpment, between the eastern and western Mediterranean Sea, is wedge-shaped, and its estimated thickness is up to 860 meters in some parts. According to the researchers, it would be the largest known megaflood deposit on Earth.<br />
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"According to the models of the paper that we published in Nature in 2009, the flood would have lasted only a few years, reaching discharges of up to 100 million cubic meters per second, about a rate thousand times the current flow of the Amazon River," adds García-Castellanos.<br />
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Researchers have also identified a spot in the channel of Sicily as the most likely gateway for the eastern Mediterranean Zanclean flood across the Malta escarpment, the submarine canyon of Noto (southeast Sicily). The authors of the study explain that this canyon has a unique morphology—its amphitheatre-shaped head is 6 km wide and is "similar to that of bedrock canyons rapidly eroded by megafloods. "The researchers interpret the Noto submarine canyon as the collector of the cascading flow into the Ionian Basin.<br />
<br />
The study points to the abrupt and catastrophic nature of the environmental changes that occurred during the Messinian period, the most important since the dinosaurs' extinction 65 million years ago," says Daniel García-Castellanos.<br />
<br />
<b>The Messinian Salinity Crisis: an unrecognizable Mediterranean Sea</b><br />
About 6 million years ago, the connection between the Atlantic Ocean and the Mediterranean Sea was interrupted. This event led to the partial desiccation of the Mediterranean Sea, which became a giant saline lake, with an estimated sea-level drawdown of 1300-2400 meters. This event is known as Messinian Salinity Crisis (MSC).<br />
<br />
A major open question about this period is how normal marine conditions were restored. The hypothesis of the Zanclean megaflood proposes that there was a massive inflow of water through the Strait of Gibraltar that first flooded the western Mediterranean Basin. Then, through the Strait of Sicily, which was once the division between the eastern and western basins, flooded the Ionian Basin. Some studies indicate that this filling process lasted between a few months and two years.<br />
<br />Explore further: <a href="https://phys.org/news/2009-12-mediterranean-sea-years.html">Mediterranean Sea filled in less than two years: study</a><br />
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<b><br /></b><div><b>Original articles: </b><br /><br /><div>
Micallef, A., et al. (2018), Evidence of the Zanclean megaflood in the eastern Mediterranean Basin, Scientific Reports, 8(1), 1078, <a href="http://dx.doi.org/10.1038/s41598-018-19446-3">DOI: 10.1038/s41598-018-19446-3</a><div><br /><div><a href="https://www.sciencedirect.com/science/article/pii/S0012825219302521">Garcia-Castellanos et al., 2020, The Zanclean megaflood of the Mediterranean – Searching for independent evidence. Earth-Science Reviews, 201, 103061. </a></div><div><br /></div><div><br /></div></div></div></div>Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com0tag:blogger.com,1999:blog-4996769537501094384.post-22439935570509355722018-02-27T13:51:00.000+01:002018-08-01T13:18:44.182+02:00Nuevos indicios de la megainundación que puso fin a la Crisis salina del Messiniense en el Mediterráneo<table style="background-color: white;"><tbody>
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" style="border: 2px solid white; cursor: move;" width="48" />(Basado en la nota de prensa de<b> Jordi Cortés </b>y<b> ICTJA_CSIC)</b></span></td></tr>
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<span style="background-color: white; color: #555555; font-family: "source sans pro" , sans-serif; font-size: 14px;">En un nuevo </span><a href="https://www.nature.com/articles/s41598-018-19446-3" style="box-sizing: border-box; color: #03acdc; font-family: "source sans pro", sans-serif; font-size: 14px; outline: none;">estudio</a><span style="background-color: white; color: #555555; font-family: "source sans pro" , sans-serif; font-size: 14px;"> realizado con Aaron Micallef (Universidad de Malta), mostramos nuevas evidencias que apoyan la hipótesis de una megainundación del Mar Mediterráneo que habría ocurrido al final del periodo Zancliense. El hallazgo de una voluminosa acumulación de sedimento cercano a las costas de Sicilia es consistente con una entrada masiva de agua en la cuenca parcialmente desecada del Mediterráneo Oriental, </span><span style="background-color: white; color: #555555; font-family: "source sans pro", sans-serif; font-size: 14px;">hace 5.3 millones de años</span><span style="background-color: white; color: #555555; font-family: "source sans pro", sans-serif; font-size: 14px;">. La inundación habría puesto fin a lo que se conoce como Crisis de Salinidad del Messiniense (CSM). El trabajo ha sido publicado en la revista Scientific Reports.</span><br />
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Gracias a los perfiles sísmicos y los testigos recuperados del fondo marino, hemos identificado en el subsuelo del canal de Sicilia una gran acumulación de sedimentos de carácter caótico y casi transparentes para las ondas sísmicas (Unidad 2 en la figura más abajo). Estos sedimentos estarían formados por los materiales erosionados y arrastrados por el inmenso flujo de agua que, a través del estrecho de Sicilia, inundó la cuenca Jónica una vez se hubo colmatado la cuenca occidental del Mediterráneo con el aporte de agua proveniente del océano Atlántico y que había entrado primero por el actual estrecho de Gibraltar.</div>
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Estos sedimentos se encuentran junto al escarpe submarino de Malta tiene forma de cuña y se le estima un grosor de hasta 860 metros en algunos puntos. Descansan encima de una capa de sales depositada con anterioridad durante la desecación parcial del mar Mediterráneo ocurrida durante la CSM y bajo otra de sedimentos de origen marino común depositados una vez se hubieron restablecido las condiciones oceánicas normales, durante el Plioceno. De confirmarse nuestra interpretación, se trataría de la mayor acumulación conocida de sedimentos originados por una mega inundación.</div>
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Hemos identificado también el lugar en el Estrecho de Sicilia por el que las aguas procedentes de la cuenca occidental del mar Mediterráneo podrían haber entrado en la cuenca Jónica durante la Mega Inundación Zancliense: el cañón submarino de Noto. Este cañón tiene una forma característica: su cabecera tiene forma de anfiteatro y una anchura cercana a los 6 kilómetros y “es similar a aquellos cañones erosionados rápidamente por mega inundaciones”. El cañón submarino de Noto podría haber actuado como el colector del inmenso flujo de agua que entró en la cuenca Mediterránea Oriental formando en este punto un salto de casi 1,5 kilómetros de altura.</div>
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<a href="https://1.bp.blogspot.com/-qARYq-sOTTc/WpVLSsUxvbI/AAAAAAAA6QA/L4iocpXJkAYEoZiQjvGPgTGPtScMAMtPQCLcBGAs/s1600/Fotos20180227_Web_02.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="400" data-original-width="1200" height="212" src="https://1.bp.blogspot.com/-qARYq-sOTTc/WpVLSsUxvbI/AAAAAAAA6QA/L4iocpXJkAYEoZiQjvGPgTGPtScMAMtPQCLcBGAs/s640/Fotos20180227_Web_02.png" width="640" /></a></div>
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Localización y estructura del cuerpo de sedimentos arrastrados por el flujo de agua de la mega inundación del periodo Zancliense (Imágen: A. Micallef et al., 2018, Sci. Reports)</div>
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Según estimaciones que publicamos en la revista Nature en 2009, <a href="http://retosterricolas.blogspot.com/2014/02/how-to-refill-mediterranean.html">la inundación del Mediterráneo habría tenido lugar en tan solo meses o unos pocos años</a>, produciéndose descargas de hasta 100 millones de metros cúbicos por segundo, unas mil veces el caudal medio del Amazonas actual.</div>
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Nuestro trabajo vuelve a poner sobre la mesa el carácter abrupto y catastrófico de los cambios medioambientales ocurridos durante el periodo Messiniense, los más importantes ocurridos desde la desaparición de los dinosaurios hace 65 millones de años.</div>
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En el estudio, liderado por Aaron Micallef de la Universidad de Malta, han participado también Angelo Camerlengui, del Istituto Nazionale di Oceanografia e di Geofisica Sperimentale de Trieste (OGS), e investigadores del Laboratoire Geosciences Océan de la Universidad de Brest y el CNRS, de la Universidad de Catania, del Institute für Geowissenshaften de la Universidad Christian-Albrechts de Kiel y del GEOMAR Helmholtz Centre for Ocean Research de Kiel, además del ICTJA-CSIC (Barcelona).</div>
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<strong style="box-sizing: border-box;">La Crisis de Salinidad del Messiniense: un Mediterráneo irreconocible</strong></div>
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Según una de las hipótesis más aceptadas, hace unos 5.5 millones de años, se cerró la conexión entre el océano Atlántico y el mar Mediterráneo y se produjo la desecación parcial del Mar Mediterráneo debido a su baja precipitación y alta evaporación. La cuenca mediterránea quedó convertida en una inmensa laguna hipersalina y sufrió un descenso del nivel de las aguas de entre 1300-2400 metros, según parte de la comunidad científica especializada en este fenómeno. Es lo que se conoce como Crisis de Salinidad del Messiniense (CMS).</div>
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Una de las grandes cuestiones sobre este periodo para los investigadores es determinar cómo las aguas recuperaron su nivel. La hipótesis de la mega inundación del Zancliense propone que se habría producido una entrada de agua masiva a través del estrecho de Gibraltar que habría inundado primero la cuenca occidental y luego, a través del estrecho de Sicilia, habría rellenado la cuenca oriental. </div>
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Artículo científico original (open access):</h4>
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Micallef, A., et al. (2018), <a href="https://www.nature.com/articles/s41598-018-19446-3" style="background-color: transparent; box-sizing: border-box; color: #03acdc; outline: none; text-decoration-line: none;">Evidence of the Zanclean megaflood in the eastern Mediterranean Basin</a>, <em style="box-sizing: border-box;">Scientific Reports</em>, 8(1), 1078, doi: 10.1038/s41598-018-19446-3.</div>
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Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com0tag:blogger.com,1999:blog-4996769537501094384.post-13074470003973550522017-09-26T12:38:00.002+02:002023-04-21T09:41:02.507+02:00Did the evaporation of the Mediterranean trigger widespread volcanism?<div class="separator" style="clear: both; text-align: center;">
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<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-JqH3baxvc9E/Wcoq4fwDruI/AAAAAAAA3ZI/dUASLrXofoczr36N_5mDHRzPJvYFpU9PwCLcBGAs/s1600/Roger%2BPibernat%2B-%2Bcascade%2B-%2Bmessi_med-300.jpg" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1217" height="320" src="https://2.bp.blogspot.com/-JqH3baxvc9E/Wcoq4fwDruI/AAAAAAAA3ZI/dUASLrXofoczr36N_5mDHRzPJvYFpU9PwCLcBGAs/s320/Roger%2BPibernat%2B-%2Bcascade%2B-%2Bmessi_med-300.jpg" width="243" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Artistic interpretation of the proposed lowstand <br />
of the Mediterranean level during the salinity <br />
crisis. Authors: Pibernat and Garcia-Castellanos</td></tr>
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130 years have gone by since the scientific recognition of a hypersaline Mediterranean sea around 6 million years ago;<br />
50 years have passed since documenting widespread submarine and riverine erosional features that suggest a subaerial exposure of parts of the Mediterranean Sea;<br />
We are 40 years after the first abissal drilling reaching the top of a salt layer thicker than 1 kilometer...<br />
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And yet, the <b>most intriguing and debated question around the Messinian salinity crisis</b> remains whether there was a large sea level fall during the <i>crisis</i>, more than a few hundreds of meters, perhaps more than a kilometer. Evidence in favor and against is piling up on the desks of geoscientists. </div>
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We now publish a new piece of evidence that supports a <i>Yes</i> answer to this long-standing question. A fall in the level of the Mediterranean Sea about 6 million years ago may have increased volcanic activity over the entire region (<a href="https://sites.google.com/site/daniggcc/publications">Sternai et al., 2017, <i>Nature Geosc.</i></a>).<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-DCo31xgM-Ss/WeTtZ4botrI/AAAAAAAA3sc/QcqSL_OIE9AEwpbUbxxh-CN4ty3xKeNSQCLcBGAs/s1600/IMG_20161028_113732%2BRealmonte%2Bmine%2B-%2Bgroup.jpg" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="903" data-original-width="1600" height="225" src="https://1.bp.blogspot.com/-DCo31xgM-Ss/WeTtZ4botrI/AAAAAAAA3sc/QcqSL_OIE9AEwpbUbxxh-CN4ty3xKeNSQCLcBGAs/s400/IMG_20161028_113732%2BRealmonte%2Bmine%2B-%2Bgroup.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Geoscientists inspecting the Realmonte mine in Sicily,<br />
where Messinian salt is commercialized. </td></tr>
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A layer ranging from 1 to 2 km of salt (halite) spreads below much of the Mediterranean seabed, formed when the Mediterranean Sea became isolated from the Atlantic Ocean about 6.0 to 5.3 million years ago, leading to evaporation and sea-level fall in an event known as the <i>Messinian salinity crisis</i>. The rate and amount of sea-level fall in the Mediterranean during this time is strongly debated. However, if the sea-level drop was dramatic and rapid, it could have unloaded the Earth’s surface, decompressing the mantle below. Such mantle decompression can enhance magma production and, in turn, lead to more frequent volcanic eruptions at the surface.<br />
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Pietro Sternai and the rest of us test this idea using a combination of geological data and numerical modelling. Dated magma intrusions and volcanic eruptions in the region show that there was a pulse of increased volcanic activity towards the end of the Messinian salinity crisis. By calculating changes in the surface load caused by a kilometre-scale drop in sea level, and taking into account the counter weight of the increased density of the remaining highly saline water and accumulating salt deposits we verify that such changes in sea level are sufficient to unload and decompress the mantle, triggering a significant increase in volcanism over the Mediterranean.<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-SlftWdmrdso/WcorOsN0SUI/AAAAAAAA3ZM/iCMdDUTu4ZM62RpwzfWxLQe1MteVq1CMACEwYBhgL/s1600/cartoon%2BMessinian%2Bdesiccation%2Brebound%2Bflexure%2Bfor%2BLofi%2BIODP%2Bproposal.jpg" style="margin-left: auto; margin-right: auto; text-align: center;"><img border="0" data-original-height="624" data-original-width="1600" height="124" src="https://1.bp.blogspot.com/-SlftWdmrdso/WcorOsN0SUI/AAAAAAAA3ZM/iCMdDUTu4ZM62RpwzfWxLQe1MteVq1CMACEwYBhgL/s320/cartoon%2BMessinian%2Bdesiccation%2Brebound%2Bflexure%2Bfor%2BLofi%2BIODP%2Bproposal.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Decompression and vertical rebound of the lithosphere <br />
in response to a sudden evaporation of the sea. </td></tr>
</tbody></table>
<br />
The results provide independent support for the idea that sea-level fall during the Messinian salinity crisis was rapid and occurred on a dramatic scale, and also highlights the sensitivity of Earth’s solid interior to changes at the surface.<br />
<br />
Check also the <a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo3040.html?WT.feed_name=subjects_climate-sciences">News & Views article by Jean-Arthur Olive</a>: “This proposed link will motivate the collection of high-resolution field data that better constrain the timing of volcanism in the Mediterranean, along with the development of novel approaches for coupled lithosphere–magma dynamics.”<br />
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Original paper:<br />
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Sternai et al, 2017, Nature Geosc. <a href="http://dx.doi.org/10.1038/ngeo3032">http://dx.doi.org/10.1038/ngeo3032</a><br />
<br />
More here:</div><div><div><a href="https://www.sciencedirect.com/science/article/pii/S0012825219302521">Garcia-Castellanos et al., 2020, The Zanclean megaflood of the Mediterranean – Searching for independent evidence. Earth-Science Reviews, 201, 103061. </a></div><div><br /></div><div><br /></div>
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Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com0tag:blogger.com,1999:blog-4996769537501094384.post-2633217528098447102016-10-04T18:53:00.000+02:002020-03-06T17:00:30.298+01:00Tomanowos - the rock that went through cosmic billiard, megafloods, and idiocy<div class="js-tweet-text-container">
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<tr><td style="text-align: center;"><img alt="" border="0" data-aria-label-part="" src="https://pbs.twimg.com/media/CszofjOXYAEtQi6.jpg" style="border: 0px; display: block; margin-left: auto; margin-right: auto; max-width: 100%; position: relative; top: 0px; width: 506px;" title="Tomanowos" /></td></tr>
<tr><td class="tr-caption">Present display of the meteorite at the <a href="https://twitter.com/AMNH">AMNH</a> museum in NY. My photo. </td></tr>
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Last week I visited again the rock with the most fascinating story on Earth: </div>
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<b><i>Tomanowos</i></b>, meaning <i>the visitor from the sky</i> in the extinct Clackamas language, also known as the Willamette meteorite. </div>
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<tr><td style="text-align: center;"><a href="https://3.bp.blogspot.com/-72AJGIiRoNs/V_PUWITyKRI/AAAAAAAAwlQ/xVCveethhccvBlFuENCrjqg3SIdnNpehgCLcB/s1600/NASA-SNR0519690-ChandraXRayObservatory-20150122.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://3.bp.blogspot.com/-72AJGIiRoNs/V_PUWITyKRI/AAAAAAAAwlQ/xVCveethhccvBlFuENCrjqg3SIdnNpehgCLcB/s200/NASA-SNR0519690-ChandraXRayObservatory-20150122.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8px; text-align: center;">Supernovas spread throughout space the<br />
iron produced in heavy stars. This ejected iron<br />
ends up in particle nebulas that eventually form<br />
new stars and <span style="font-size: 12.8px;">protoplanets. [Image: NASA] </span></td></tr>
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When European Americans <i>found</i> it near the Willamette River (Portland, OR) more than a century ago, Tomanowos inevitably went through one of the most hilarious and silly geological stories that I know of, surely driven by the fatal attraction that a rare rock like this exerts on humans. But before going into that let me tell a few things about its origins.<br />
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Tomanowos is a rare 15 ton <a href="https://en.wikipedia.org/wiki/Meteorite_classification">meteorite</a> made of iron and nickel (Fe 91%, Ni 7.6%). As in other metal meteorites, these <i>Fe</i> and <i>Ni</i> atoms <b>formed at the core of stars </b>that shattered the space with the products of nuclear fusion when ending their lives in supernovae explosions. These elements ended up in the nebula that clumped together as protoplanets in our Solar System, and Tomanowos was part of the core of one of these<b> protoplanets</b>, where the heavier metals accumulate. </div>
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<tr><td style="text-align: center;"><a href="https://3.bp.blogspot.com/--ymTL4xv6Qg/WATnidArosI/AAAAAAAAwp0/esJ_VwTMMaU4rPEnwtub9J6ouZ8rvUpnwCLcB/s1600/Vesta%2Bstructure%2BEPFL-Jamani%2BCaillet%252C%2BHarold%2BClenet.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="266" src="https://3.bp.blogspot.com/--ymTL4xv6Qg/WATnidArosI/AAAAAAAAwp0/esJ_VwTMMaU4rPEnwtub9J6ouZ8rvUpnwCLcB/s320/Vesta%2Bstructure%2BEPFL-Jamani%2BCaillet%252C%2BHarold%2BClenet.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div style="font-size: 12.8px; text-align: center;">
Vesta, a surviving protoplanet of <span style="font-size: 12.8px;">the </span></div>
<div style="font-size: 12.8px; text-align: center;">
<span style="font-size: 12.8px;">early Solar System. Due to </span><span style="font-size: 12.8px;">their large</span></div>
<span style="font-size: 12.8px;"> size, protoplanets develop a differenciated </span><br />
<span style="font-size: 12.8px;">density distribution with heavier elements like </span><br />
iron <span style="font-size: 12.8px;">concentrated in the core. Tomanowos is an </span><br />
<span style="font-size: 12.8px;">ejected </span><span style="font-size: 12.8px;">piece of a protoplanet core like this. </span><br />
[EPFL/Jamani Caillet, Harold Clenet]</td></tr>
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We also know that later on, about<b> 4 billion years ago, a collision </b>between two of those protoplanets sent our museum piece back to space solitude. Subsequent impacts over billions of years eventually made the orbit of this meteorite cross that of the Earth. As a result of such <b>cosmic billiard</b>, the meteorite entered our atmosphere at a speed of ~60,000 km/h nearly 20,000 years ago and <b>landed on an ice cap in Canada</b>.<br />
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Over the following decades, the ice flow slowly transported Tomanowos southwards, towards a glacier lobe that was at the time blocking the Fork River in Montana (USA). The glacial tongue piled ice across the river valley forming a 600-m-high ice-dam that impounded the enormous Lake Missoula. Following the ice flow, Tomanowos happened to reach the dam on the precise year when it collapsed, releasing one of the <b>largest floods ever documented: the </b><a href="https://twitter.com/hashtag/MissoulaFloods?src=hash" style="font-weight: bold;">#MissoulaFloods</a> that shaped the Scablands in Washington. This process is known as <i>glacial outburst flooding</i> and it still happens every few years in the <a href="https://www.theguardian.com/world/video/2016/mar/10/part-of-perito-moreno-glacier-collapses-video">Perito Moreno glaciar</a>, for example. Except that the water discharge during the Missoula Floods reached the equivalent to a <b>few thousand Niagara Falls</b>. The research of the Missoula floods by <a href="https://en.wikipedia.org/wiki/J_Harlen_Bretz#The_Spokane_floods:_an_outrageous_hypothesis">Bretz</a> and <a href="https://en.wikipedia.org/wiki/Joseph_Pardee">Pardee</a> in the early 20th century led to one of the most significant paradigm shifts in recent geoscience: the recognition that catastrophic events can significantly contribute to the evolution of landscape.</div>
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-pWd-BGxeamw/V_OvkEiZ-iI/AAAAAAAAwks/003iq4wosok0meOVSLtHA6DoD1VFCpjZwCLcB/s1600/floodsmap_lg.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="199" src="https://1.bp.blogspot.com/-pWd-BGxeamw/V_OvkEiZ-iI/AAAAAAAAwks/003iq4wosok0meOVSLtHA6DoD1VFCpjZwCLcB/s320/floodsmap_lg.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8px; text-align: center;">Map of the <a href="https://en.wikipedia.org/wiki/Missoula_Floods">Missoula Floods</a> path, showing <span style="font-size: 12.8px;">Lake </span><span style="font-size: 12.8px;">Missoula </span><br />
<span style="font-size: 12.8px;">(blue),</span><span style="font-size: 12.8px;"> </span><span style="font-size: 12.8px;">the ice </span><span style="font-size: 12.8px;">cap where </span><span style="font-size: 12.8px;">Tomanowos landed (north of the </span><br />
<span style="font-size: 12.8px;">lake outlet), and the </span><span style="font-size: 12.8px;">inundated </span><span style="font-size: 12.8px;">areas </span><span style="font-size: 12.8px;">of Washington </span><span style="font-size: 12.8px;">and </span><br />
<span style="font-size: 12.8px;">Oregon (grey).</span><br />
Source: Washington Univ.</td></tr>
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<b>Trapped in ice and rafted</b> down by the flood, Tomanowos crossed Idaho, Washington and Oregon along the overflown Columbia River at speeds sometimes faster than 20 meters per second. While floating up on the flood waters near today's Portland, the ice case broke apart and the meteorite sunk in the flooding waters. Hundreds of other ice-rafted <i>erratics</i> (rocks that do not match the local geology, nor could be transported by rivers or glaciers) have been found along the Columbia River. All are souvenirs from the Missoula floods, but none as rare as Tomanowos.<br />
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As the flood ceased, the sunk meteorite became exposed to the atmosphere. Over thousands of years, rain mixed with the iron sulfide inclusions producing sulfuric acid that gradually <b>dissolved the iron</b> of the exposed side of the rock:</div>
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<tr><td class="tr-caption" style="font-size: 12.8px;">These cavities were produced by acid dissolution of iron at the exposed side.</td></tr>
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<a href="https://www.blogger.com/blogger.g?blogID=4996769537501094384" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"></a>A few thousand years after the flood, <b>the Clackamas arrived to Oregon and named the meteorite as the Visitor of the Sky</b>, a heaven's representative that unified earth, water & sky. Apparently they knew that nickel rocks come from heaven. Were they intrigued by the absence of a crater at the Meteorite site? In any case, the name reminds us that pre-scientific cultures were not idiotic, or not more than us today anyway.<br />
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To confirm this latter hypothesis, in 1902 a colonist named Ellis Hughes decided to secretly move the iron rock to his own land and then claim property. Millennia of peaceful rest in the Willamette valley had to come to an end. But because moving a 15-ton rock a distance of 1,200 m without being noticed is not easy, not even in Oregon, Hughes and his son labored for three back-breaking months in secrecy: </div>
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<tr><td><a href="https://2.bp.blogspot.com/-Lg4SSSb6l-4/V_PANfXOlpI/AAAAAAAAwk8/z5NzSoBJYnUAz41PDr8kOrrlUGiY7eGLQCLcB/s1600/hughes-with-meteorite1.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="250" src="https://2.bp.blogspot.com/-Lg4SSSb6l-4/V_PANfXOlpI/AAAAAAAAwk8/z5NzSoBJYnUAz41PDr8kOrrlUGiY7eGLQCLcB/s320/hughes-with-meteorite1.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8px;"><span style="font-size: 12.8px;">As </span><a href="http://www.usgennet.org/usa/or/county/clackamas/MeteorTreasures.html" style="font-size: 12.8px;">D. J. Preston</a><span style="font-size: 12.8px;"> hilariously explains, after finally</span><br />
succeeding with the moving, Hughes built a shack around <br />
the meteorite, announced he had found it on his property<br />
and started charging twenty-five cents admission to view <br />
the <i>heavenly visitor</i>.</td></tr>
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It was during this transport that the rock sadly underwent severe mutilations.<br />
Unimpressed by this deployment of idiocy, Hughes' neighbor fabricated a lawsuit contending that the meteorite had, in fact, landed on HIS property. And to buttress his case he showed investigators a huge crater on his land. The case was dismissed when a third neighbor reported a great deal of blasting only the week before the trial.<br />
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<a href="https://www.blogger.com/blogger.g?blogID=4996769537501094384" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"></a><b>Iron</b>ically, the legitimate owner of the original land of the <b>iron</b> rock turned out to be the <i>Oregon <b>Iron</b> and Steel Company,</i> so far unaware of the meteorite but promptly <a href="http://www.usgennet.org/usa/or/county/clackamas/MeteorTreasures.html">hiring a twenty-four-hour guard</a> who sat on top of it with a loaded gun while the case was being appealed. They won the case in 1905, selling Tomanowos to the AMNH museum in New York a year later.</div>
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<tr><td><a href="https://3.bp.blogspot.com/-avUoqfxGSFE/V_Ok90-fArI/AAAAAAAAwkU/U1oL1Abu620j6ahyoUXq0nyO8sJNF1CFQCLcB/s1600/The_American_Museum_journal_%2528c1900-%25281918%2529%2529_%252817973455149%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="186" src="https://3.bp.blogspot.com/-avUoqfxGSFE/V_Ok90-fArI/AAAAAAAAwkU/U1oL1Abu620j6ahyoUXq0nyO8sJNF1CFQCLcB/s320/The_American_Museum_journal_%2528c1900-%25281918%2529%2529_%252817973455149%2529.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8px;">Tomanowos in the early 1900s, before being transported to the AMNH.</td></tr>
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Today, amazingly enough, the <a href="https://twitter.com/AMNH">AMNH</a> exhibition does not even mention the Missoula Floods as a key part of Tomanowos' story, in spite of the wide scientific consensus. Same as the meteorite, <b>the Clackamas were also reallocated </b>to a reservation. Their descendants <a href="http://www.amnh.org/exhibitions/permanent-exhibitions/rose-center-for-earth-and-space/dorothy-and-lewis-b.-cullman-hall-of-the-universe/willamette-meteorite-agreement">do keep the right</a> to visit Tomanowos in NY and talk to <i>the visitor who brought the Sky, the Water, and the Earth together</i>.<br />
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[Update: <a href="https://www.youtube.com/watch?v=tyhHjDLwHlI">my conference on outburst floods at the PAGES meeting, 2017</a>]<br />
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Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com1Portland, OR, USA45.5230622 -122.6764815999999945.167186199999996 -123.32192859999999 45.8789382 -122.03103459999998tag:blogger.com,1999:blog-4996769537501094384.post-6756292850983676772016-04-27T16:56:00.001+02:002016-06-22T23:56:39.941+02:00Glacier retreat in southern IcelandLooking at old pictures, I realise that I had a first-hand glance at the retreat of the Jökulsárlón glacier (S. Iceland) back in 2013. I took these two pictures from the same spot with an 18-years time lag. Although the first one is taken in August and accordingly shows less snow in the background mountains than the more recent one, the latter does show the glacier front retreated by about 3 km. I pasted the Landsat images for comparison.<br />
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<a href="https://4.bp.blogspot.com/-IHCzj889Hwk/VyDKd4qgoQI/AAAAAAAAsMI/6Gl7CTQap28sRrSqwX0bgA02kD0sjZMMQCLcB/s1600/Dani%2BIsland%2Bglacier%2B1995-2013.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="219" src="https://4.bp.blogspot.com/-IHCzj889Hwk/VyDKd4qgoQI/AAAAAAAAsMI/6Gl7CTQap28sRrSqwX0bgA02kD0sjZMMQCLcB/s640/Dani%2BIsland%2Bglacier%2B1995-2013.jpg" width="640" /></a></div>
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Not that this is a surprise, really: </div>
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<a href="https://3.bp.blogspot.com/-3QW8mN3DpuQ/VyDL2NnjPtI/AAAAAAAAsMU/nKx9z-zW2GYMIIFnJdJWRUraLB6Uzo1VACLcB/s1600/glacier%2Bretreat%2BOrlove%2BFigure%2B1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="560" src="https://3.bp.blogspot.com/-3QW8mN3DpuQ/VyDL2NnjPtI/AAAAAAAAsMU/nKx9z-zW2GYMIIFnJdJWRUraLB6Uzo1VACLcB/s640/glacier%2Bretreat%2BOrlove%2BFigure%2B1.jpg" width="640" /></a></div>
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But i had to share.<br />
In the meanwhile, I found this other <a href="http://www.eorc.jaxa.jp/en/earthview/2011/tp110112.html">JAXA (Japan) link</a> as well. </div>
Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com0tag:blogger.com,1999:blog-4996769537501094384.post-86897773537160062522016-02-24T15:45:00.000+01:002016-04-26T14:49:29.831+02:00Extreme Geodynamics at the Tsangpo GorgeIf you aim at understanding what shapes the surface of the Earth, the Tsangpo Gorge (Eastern syntax of the Himalayas) will inevitably become one of your favorite places.<br />
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-yD6r5iBbkvM/VktcA5Z7wYI/AAAAAAAApM0/M8Nt29KdtjE/s1600/Tsangpo%2Bgorge%2Bfastest%2Berosion%2B1%2Bcm-yr.png" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto; text-align: center;"><img border="0" height="320" src="https://2.bp.blogspot.com/-yD6r5iBbkvM/VktcA5Z7wYI/AAAAAAAApM0/M8Nt29KdtjE/s320/Tsangpo%2Bgorge%2Bfastest%2Berosion%2B1%2Bcm-yr.png" width="203" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">This is the place where bedrock is <br />
being eroded at the fastest <br />
measured rate of nearly 1 mm/yr.<br />
The uncommonly vertical valley<br />
walls adopt this high angle to cope<br />
by landsliding with the incision rates<br />
produced by water. </td></tr>
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This is the place on Earth where one of the <b>the highest bedrock erosion rates, the fastest tectonic uplift, and some of the highest topographic gradients</b> have been measured. Every year, nearly 1 cm of very hard metamorphic rock is dig by the Tsangpo River, which descends from an elevation of >3000 m near the Tibetan plateau, to a mere 1000 m in less than 100 km. An average water discharge above 1400 m3/s, together with the pronounced slope, implies a huge erosion power.<br />
Upstream from this gorge, there are widespread terraces and shore sediments of a lake that used to cover a few hundred kilometers of the river valley and impounded up to 800 km3 of water in a lake. What caused this impoundment is a matter of discussion: Only the tectonic uplift along the gorge? Or also an increase in landsliding from the valley flanks during the Pleistocene? Or glacial moraine accumulations?<br />
The long duration of this competition between uplift and erosion (at least 10 Myr) implies that the region must be approximately in equilibrium, so uplift rates are presumably in the range of a cm per year, only comparable to the post-glacial isostatic rebound of Scandinavia.<br />
<iframe allowfullscreen="" frameborder="0" height="500" src="https://www.google.com/maps/embed?pb=!1m14!1m12!1m3!1d587272.5212916508!2d94.8013075491328!3d29.5240382479154!2m3!1f0!2f0!3f0!3m2!1i1024!2i768!4f13.1!5e1!3m2!1sen!2ses!4v1436099318002" style="border-style: initial; border-width: 0px;" width="670"></iframe><br />
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A recent study of the infill of those lake sediments concludes that the steepening of the Tsangpo Gorge started about 2 to 2.5 million years ago as a consequence of a faster rock uplift: </div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://3.bp.blogspot.com/-NPehqUx0ax8/Vs20LQZo0eI/AAAAAAAArBY/MF52qvvXFTk/s1600/Screen%2BShot%2B2016-02-24%2Bat%2B14.45.19.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="640" src="https://3.bp.blogspot.com/-NPehqUx0ax8/Vs20LQZo0eI/AAAAAAAArBY/MF52qvvXFTk/s640/Screen%2BShot%2B2016-02-24%2Bat%2B14.45.19.png" width="611" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">(A) Longitudinal river profile of the Tsangpo River, location of drill cores with observed depth to bedrock (vertical black bars), estimated depth to bedrock (yellow area), and reconstructed valley bottom before uplift of Tsangpo Gorge (dashed line). (B) Hillslope angles at the river flanks, specific stream power, and landslide erosion rates. (C) Erosion rates of close to 10 mm/yr are reflected in the age at which the minerals cooled down while being exhumed towards the surface. From Wang et al., 2014, Science. </td></tr>
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The extreme uplift and exhumation rates have been linked to a feedback effect of erosion on channelizing crustal rock towards the surface (the so called tectonic aneurysm; <span style="font-size: xx-small;">Montgomery & Stolar, 2006</span>).<br />
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In contrast, other studies favor the role of glacial transport from the high surrounding mountains near the gorge in blocking the river with glacial moraines. This may have triggered megafloods sourced at impoundments formed by glacial dams (<span style="font-size: xx-small;">Lang et al., 2013, Geology</span>), since some of the largest known outburst floods in the world have also been reported here.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-liSC7y-Mgks/VZkqdmTrEbI/AAAAAAAAl7g/QL3Bf88i4Jw/s1600/Tsangpo%2BGorge%2Bfastest%2Berosion.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="267" src="https://4.bp.blogspot.com/-liSC7y-Mgks/VZkqdmTrEbI/AAAAAAAAl7g/QL3Bf88i4Jw/s400/Tsangpo%2BGorge%2Bfastest%2Berosion.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 16px; text-align: center;">Tsangpo Gorge</td></tr>
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Hence, the competition between tectonic uplift and erosion at the Tsangpo encompasses many of the <a href="http://retosterricolas.blogspot.com/p/open-questions-in-geoscience.html">big conundrums in present geomorphology and geodynamics</a>: the importance of episodicity in landscape evolution, the implications of the glacial ages on erosion rates, the possible effects of climate on tectonic deformation...Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com0Mainling, Nyingchi, Tibet, China29.754243854706683 95.13679504394531229.699106854706685 95.056114043945314 29.809380854706681 95.217476043945311tag:blogger.com,1999:blog-4996769537501094384.post-16420900722374215082015-11-16T19:40:00.001+01:002022-01-21T21:10:39.636+01:00How do we know that the Earth has a core?<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td class="tr-caption" style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEhz_c44Bk9xZxBiW0oBXoI8CORP-NPC4pmyQncZ30r9zDyPKGZftq6n0Rn4nNPY-zYI-1En62CSG1T0y9p8hAF7Pkmy3eqxakvaz64be-qr97cuSxI01tzEAX0ka751lHbPUczSBb7JX_pEM29jXkC0XLABVcNLFURtROK8a-ed4v_SD80leFfbeIAUeg=s2560" imageanchor="1" style="clear: right; display: inline !important; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1583" data-original-width="2560" height="198" src="https://blogger.googleusercontent.com/img/a/AVvXsEhz_c44Bk9xZxBiW0oBXoI8CORP-NPC4pmyQncZ30r9zDyPKGZftq6n0Rn4nNPY-zYI-1En62CSG1T0y9p8hAF7Pkmy3eqxakvaz64be-qr97cuSxI01tzEAX0ka751lHbPUczSBb7JX_pEM29jXkC0XLABVcNLFURtROK8a-ed4v_SD80leFfbeIAUeg=w320-h198" title="1. A typical depiction of the core of the Earth." width="320" /></a><br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td class="tr-caption"><div style="text-align: center;">1. A typical depiction of the core</div><div style="text-align: center;">of the Earth.</div></td></tr></tbody></table><br /></td></tr></tbody></table>Many of us have wondered, at some point of our lives, why the cartoons depicting the Earth as a watermelon with a missing portion always show this ball in the center named the 'core'. <b>How do we know that a distinct 'body' is actually down there, 2900 km below the surface?</b><div>
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Let's see: we know the total mass of the Earth through its gravitational interaction with the solar system. In 1797, <a href="https://en.wikipedia.org/wiki/Cavendish_experiment">Cavendish</a> <span style="font-size: x-small;">[ref.1]</span><a href="https://en.wikipedia.org/wiki/Cavendish_experiment"> measured the Gravitational constant <i>G</i></a> and the density of the Earth is ever since known to be about 5.51 times the density of water: nearly twice the average rock density we find at the surface.<br />
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In 1898, <a href="https://en.wikipedia.org/wiki/Emil_Wiechert">Wiechert suggested</a> <span style="font-size: x-small;">[ref.2]</span><a href="https://en.wikipedia.org/wiki/Emil_Wiechert"> that this high Earth’s density could be explained by a core in the center</a> made of nickel and iron (like many meteorites known at the time) surrounded by a shell, or <b>mantle,</b> of the lighter silicon-dominated rocks that we see in the surface.<br />
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-fxuU5GerK9U/Vf19hU60SwI/AAAAAAAAn0Y/mXaBc-k9omc/s1600/inge-lehmann%252C%2Binner%2Bcore.jpg" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://2.bp.blogspot.com/-fxuU5GerK9U/Vf19hU60SwI/AAAAAAAAn0Y/mXaBc-k9omc/s320/inge-lehmann%252C%2Binner%2Bcore.jpg" width="253" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">2. <a href="https://en.wikipedia.org/wiki/Inge_Lehmann" style="text-align: right;">Inge Lehmann</a><span style="text-align: right;"> was one of the key</span><br />
<span style="text-align: right;">discoverers of the inner core of the Earth.</span></td></tr>
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But only in 1906, <a href="https://en.wikipedia.org/wiki/Richard_Dixon_Oldham">Richard D. Oldham</a> found that the increasing speed of <a href="https://en.wikipedia.org/wiki/Seismic_wave">seismic waves</a> with depth within the Earth holds only down to 2890 km below the surface. Deeper than that, the mechanical (acoustic) waves propagate much slower (fig. 6), suggesting a different rock nature. Because this distinct material did not transmit <a href="https://en.wikipedia.org/wiki/S-wave">shear seismic waves</a>, it became clear that this<b> <i>core</i> is liquid</b>.<br />
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But in 1936, <a href="https://en.wikipedia.org/wiki/Inge_Lehmann">Inge Lehmann</a> (picture on the right) found that the center of the core is indeed nearly-solid, since she inferred weak shear waves travelling through it <a href="https://en.wikipedia.org/wiki/Inner_core#cite_note-4">[ref. 4]</a> using highly-sensitive <a href="https://en.wikipedia.org/wiki/Seismographs">seismometers</a> in New Zealand. This has become known as the <b>inner core</b>.<br />
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3. Images of the tsunami following last week's earthquake in Chile.</div>
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Today, detecting the core down there has become a doable task for anyone. <b>Last week's earthquake in Chile, for example, provides a great opportunity</b> for you to <b>check if Oldham did everything right</b>. You only need to get seismograms from seismic stations around the world (many of these stations have their data available online, real time), and sort the signals according to the distance from the station to the EQ's epicenter, using the same time of reference, like in this image:<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-gOwOYO7KeZI/Vf2Hk3ouVAI/AAAAAAAAn0o/pAJt5ZE2KGA/s1600/2015-10%2BChile%2Bearthquake%2Bearths%2Bcore%2Bseismograms.png" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://1.bp.blogspot.com/-gOwOYO7KeZI/Vf2Hk3ouVAI/AAAAAAAAn0o/pAJt5ZE2KGA/s400/2015-10%2BChile%2Bearthquake%2Bearths%2Bcore%2Bseismograms.png" width="358" /></a><a href="https://pbs.twimg.com/media/CPF6arVWEAEZLYJ.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="200" src="https://pbs.twimg.com/media/CPF6arVWEAEZLYJ.png" width="181" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">4. Left: Each horizontal line is a seismogram of the Chile earthquake recorded at different locations of the planet (check USGS: <a href="http://earthquake.usgs.gov/earthquakes/eventpage/us20003k7a#general_summary">2015-10-16; Mw=8.3</a>). Each seismogram is plotted according to the distance of the measuring station to the earthquake (vertical axis). The red circle shows the signal gap due to the outer core.<br />
Right: Same image, with the identification of the arrivals of the different seismic waves. 'P' waves are the compressional waves, they are first to arrive all around the planet's surface.<br />
The horizontal axis shows elapsed time, measured since the EQ occurred. <br />
The vertical axis shows the distance from the measuring station to the EQ. <br />
The red circle shows the region (around 110 degrees from the source) where the first seismic waves are not recorded. </td></tr>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td><a href="http://1.bp.blogspot.com/-kY2w6-d_R1A/Vf2Q3Ggj18I/AAAAAAAAn1A/geEuh_onBI4/s1600/seismic%2Bshadow%2Bzone%2Bcore%2Bmantle%2B2.JPG" style="margin-left: auto; margin-right: auto;"><img border="0" height="248" src="https://1.bp.blogspot.com/-kY2w6-d_R1A/Vf2Q3Ggj18I/AAAAAAAAn1A/geEuh_onBI4/s320/seismic%2Bshadow%2Bzone%2Bcore%2Bmantle%2B2.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 16px;">5. Seismic shadow produced by an imaginary <br />
earthquake occurring at the north pole. The <br />
outer core, due to its slower seismic velocity, <br />
refracts the mechanical waves of the earthquake,<br />
shadowing a vast region of the planet, as seen<br />
in figure 4.</td></tr>
</tbody></table>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://pbs.twimg.com/media/CPRWH85WIAEEWAi.png" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="135" src="https://pbs.twimg.com/media/CPRWH85WIAEEWAi.png" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 16px; text-align: center;">6. The velocity of seismic waves<br />
changes with depth within the Earth.</td></tr>
</tbody></table>
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In summary: the absence of wave reception in regions around 14,000 km (between 103 and 143 degrees) apart from the hypocenter demonstrates that there is a liquid core where seismic waves travel slow.<br />
Isn't it amazing that nobody realized this before the 20th century? <br />
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Finally, remember that the <a href="https://en.wikipedia.org/wiki/Outer_core">outer core</a> is where the magnetic field of the Earth is generated, by the thermal convection of conductive molten iron around a nearly-solid iron inner core. In fact the changes in the convection patterns in the outer core seem responsible for the rapid historical changes observed in the magnetic field. There is <a href="http://retosterricolas.blogspot.com/2012/03/seafloor-spreading-hypotheses-and.html">more about the magnetic field in this earlier post</a>.<br />
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<a href="https://3.bp.blogspot.com/-G5CA0HbEN2c/U7rZfXiWPxI/AAAAAAAAb1Q/WJEzKdoAzTE/s1600/NASA_54559main_comparison1_strip.gif" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="245" data-original-width="448" height="175" src="https://3.bp.blogspot.com/-G5CA0HbEN2c/U7rZfXiWPxI/AAAAAAAAb1Q/WJEzKdoAzTE/s320/NASA_54559main_comparison1_strip.gif" width="320" /></a></div>
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<tr><td class="tr-caption" style="text-align: center;">7. Convection in the iron-dominated outer core around<br />
a nearly solid core is <span style="font-size: 12.8px;">widely accepted as the </span><a href="https://retosterricolas.blogspot.com/2012/03/seafloor-spreading-magnetic-reversals.html" style="font-size: 12.8px;">cause for the </a><br />
<a href="https://retosterricolas.blogspot.com/2012/03/seafloor-spreading-magnetic-reversals.html" style="font-size: 12.8px;">Earth's magnetic field</a>, and known as the <i>geodynamo</i><span style="font-size: 12.8px;">. </span><br />
<span style="font-size: 12.8px;">(Glatzmaier & Roberts).</span></td></tr>
</tbody></table>
Update 2015-11: a new study suggests that the core (and thus the magnetic field) was <a href="http://phys.org/news/2015-10-earth-core-billion-years.html">formed by the gradual cooling of the Earth only 1 to 1.5 billion years ago</a>.<br />
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Update 2015-12: Geophysicists call it the new core paradox: They can't quite explain how the ancient Earth could have sustained a magnetic field billions of years ago, as it was cooling from its fiery birth. Now, two scientists have proposed two different explanations. <a href="http://ow.ly/W3eQX">http://ow.ly/W3eQX</a><br />
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References<span style="font-size: x-small;"> (thank you <a href="http://nuclearplanet.com/Earth%20Core%20Discovery.html"><i>nuclearplanet</i></a>)</span>:<br />
<span style="font-size: xx-small;">1. Cavendish, H., Experiments to determine the density of Earth. Philosophical Transactions of the Royal Society of London, 1798, 88, 469-479.</span><br />
<span style="font-size: xx-small;">2. Wiechert, E., Über die Massenverteilung im Inneren der Erde. Nachr. K. Ges. Wiss. Goettingen, Math-Kl., 1897, 221-243.</span><br />
<span style="font-size: xx-small;">3. Oldham, R. D., The constitution of the interior of the Earth as revealed by earthquakes. Q. T. Geol. Soc. Lond., 1906. 62, 459-486.</span><br />
<span style="font-size: xx-small;">4. Lehmann, I., P'. Publ. Int. Geod. Geophys. Union, Assoc. Seismol., Ser. A, Trav. Sci., 1936, 14, 87-115.</span><br />
<br /></div>Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com0tag:blogger.com,1999:blog-4996769537501094384.post-55166883620429118352015-11-03T12:42:00.000+01:002015-11-04T14:43:35.370+01:00Conferencias de divulgación geocientífica (50 aniversario del ICTJA)Con motivo del 50 aniversario de nuestro instituto, cuatro investigadores del <a href="http://www.ictja.csic.es/">ICTJA</a> participamos en el ciclo de conferencias divulgativas en Barcelona: "Las Ciencias de la Tierra en nuestra vida cotidiana", dentro del <a href="http://www.residencia-investigadors.es/es/actividades/charles-darwin-lord-kelvin-los-radioisotopos-y-el-concepto-de-tiempo-813.htm"><i>Cicle Dilluns de Ciència</i> del CSIC-Catalunya</a>.<br />
<br />
<a href="http://3.bp.blogspot.com/-V0BDkFHAeuc/Vjiat9l-EOI/AAAAAAAAo7k/r5vrdaJDn4g/s1600/A-ICTJA-CSIC_201510116.tiff" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="640" src="http://3.bp.blogspot.com/-V0BDkFHAeuc/Vjiat9l-EOI/AAAAAAAAo7k/r5vrdaJDn4g/s640/A-ICTJA-CSIC_201510116.tiff" width="332" /></a>Lugar: (<a href="https://www.google.es/maps/place/Resid%C3%A8ncia+d'Investigadors/@41.3802601,2.1693975,15z/data=!4m2!3m1!1s0x0:0x8d02d1fe8a39562f?sa=X&ved=0CJUBEPwSMAtqFQoTCNqohJuU9MgCFcy-FAodYfcBpw">mapa</a>)<br />
Sala d’Actes de la Residència d’Investigadors,<br />
CSIC-Catalunya,<br />
Barcelona<br />
<br />
La conferencias de divulgación son los siguientes lunes:<br />
<br />
2 Novembre, 18:30 h,<br />
<b><a href="http://www.residencia-investigadors.es/es/actividades/charles-darwin-lord-kelvin-los-radioisotopos-y-el-concepto-de-tiempo-813.htm">Charles Darwin, Lord Kelvin, els radioisòtops i el concepte de Temps</a></b><br />
<div>
Dr. Santiago Giralt</div>
<br />
9 Noviembre, 18:30 h<br />
<b><a href="http://www.residencia-investigadors.es/es/actividades/tambora-200-anos-de-la-erupcion-que-cambio-el-mundo-814.htm">Tambora, 200 años de la erupción que cambió el Mundo</a></b><br />
Dra. Adelina Geyer<br />
<br />
16 Noviembre, 18:30 h<br />
<b><a href="http://www.residencia-investigadors.es/es/actividades/megainundaciones-placas-tectonicas-y-la-formacion-del-relieve-terrestre-815.htm">Megainundaciones, placas tectónicas y la formación del relieve terrestre</a></b><br />
Dr. Daniel García-Castellanos<br />
<br />
23 Novembre, 18:30 h<br />
<b><a href="http://www.residencia-investigadors.es/es/actividades/lunes-de-ciencia-las-ciencias-de-la-tierra-en-nuestra-vida-cotidiana-816.htm">Interacció radiació-matèria per a estudiar-ho gairebé tot: nanomaterials, minerals exòtics, obres d’art, cadàvers,...</a></b><br />
Dr. Jordi Ibáñez<br />
<br />Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com0Carrer de l'Hospital, 64, 08001 Barcelona, Barcelona, Spain41.3802459 2.1693731000000341.379501399999995 2.16811260000003 41.3809904 2.1706336000000297tag:blogger.com,1999:blog-4996769537501094384.post-35271849374785821022015-08-06T13:11:00.000+02:002015-08-06T13:11:06.324+02:00Continental-scale evolution of topography and river networks. Tectonics and climate shaping Eurasia<span style="font-size: x-small;">[This post is about our recent <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0132252">publication on PLOS ONE</a>]</span><br />
<br />
How much does the erosion and sedimentation at the Earth’s surface influence on the patterns and distribution of tectonic deformation? This question has been mainly addressed from a computer modelling perspective, at scales ranging from local to orogenic. In the PLOS ONE paper published today, we present a model that aims at understanding this phenomenon at the continental scale, looking at the feedbacks between continental enlargement and climate aridification during the collision of continents.<br />
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<span style="background-color: white; color: #333333; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; text-align: start;">60-million-year indentation of a continent from the south </span></div>
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<span style="background-color: white; color: #333333; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; text-align: start;">(at 50 mm/yr). </span></div>
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<span style="background-color: white; color: #333333; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; text-align: start;">Left: Topography and areas with precipitation<br />higher than 400 mm/yr (red shading). Note the </span></div>
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<span style="background-color: white; color: #333333; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; text-align: start;">orographic rainfall developing at the southern flank </span></div>
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<span style="background-color: white; color: #333333; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; text-align: start;">of the growing </span><span style="background-color: white; color: #333333; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; text-align: start;">plateau. Wind blows from the southeast </span></div>
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<span style="background-color: white; color: #333333; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; text-align: start;">(towards </span><span style="background-color: white; color: #333333; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; text-align: start;">the </span><span style="background-color: white; color: #333333; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; text-align: start;">upper left corner).</span></div>
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<span style="background-color: white; color: #333333; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; text-align: start;">Right: erosion and sedimentation rates, and<br />contours of crustal thickening rate due to tectonics. </span></div>
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<span style="background-color: white; color: #333333; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; text-align: start;">By Garcia-Castellanos & Jimenez-Munt, PLOS ONE, 2015. </span></div>
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<span style="background-color: white; color: #333333; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; text-align: start;">+ info </span><a class="yt-uix-redirect-link" dir="ltr" href="https://sites.google.com/site/daniggcc/software/uhurutisc" rel="nofollow" style="background: rgb(255, 255, 255); border: 0px; color: #167ac6; cursor: pointer; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; margin: 0px; padding: 0px; text-align: start; text-decoration: none;" target="_blank" title="https://sites.google.com/site/daniggcc/software/uhurutisc">here.</a></div>
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We couple a thin-sheet viscous model of continental deformation with a stream-power surface transport model. The model also incorporates flexural isostatic compensation that permits the formation of large sedimentary basins and a precipitation model that reproduces basic climatic effects such as continentality and orographic rainfall and rain shadow. We calculate the feedbacks between these four processes acting at different scales in a synthetic scenario inspired and scaled by the India-Asia collision. The model reproduces first-order characteristics of the growth of the Tibetan Plateau as a result of the Indian indentation.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-WULja_w0ZG0/Up4YN8BMMFI/AAAAAAAAYHE/2QwUo_-Kxm0/s1600/UhuruTISC%2Bmethod%2Banim.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="640" src="http://3.bp.blogspot.com/-WULja_w0ZG0/Up4YN8BMMFI/AAAAAAAAYHE/2QwUo_-Kxm0/s640/UhuruTISC%2Bmethod%2Banim.gif" width="351" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8000001907349px; text-align: center;"><span style="background-color: white; color: #333333; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; text-align: start;">Note that the southern continent (the indenter, India)<br />is chosen fixed to our reference frame, whereas<br /> the northern continent (Asia) is moving southwards). </span><br />
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<span style="background-color: white; color: #333333; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; text-align: start;">The initial topography is flat with small random noise<br />forming a network of lakes. </span><span style="background-color: white; color: #333333; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; text-align: start;">The tectonic indenter in<br />the southern boundary represents India, while a rigid<br />block fixed around x=2500km represents the Tarim Basin. </span><br />
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<span style="background-color: white; color: #333333; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; text-align: start;">Wind blowing from SE at 7 m/s (relative humidity=1).<br />Red shading indicates orographic precipitation.</span><br />
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<span style="background-color: white; color: #333333; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; text-align: start;">The continental deformation adopts a thin-sheet tectonic<br />model. </span><span style="background-color: white; color: #333333; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; text-align: start;">+ info </span><a class="yt-uix-redirect-link" dir="ltr" href="https://sites.google.com/site/daniggcc/software/uhurutisc" rel="nofollow" style="background: rgb(255, 255, 255); border: 0px; color: #167ac6; cursor: pointer; font-family: Roboto, arial, sans-serif; font-size: 13px; line-height: 17px; margin: 0px; padding: 0px; text-align: start; text-decoration: none;" target="_blank" title="https://sites.google.com/site/daniggcc/software/uhurutisc">here.</a></td></tr>
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What these simulations show is that, at large space and temporal scales, the climate dryness that develops in continental interiors triggers the trapping of sediment in closed basins within the continent, instead of exporting it to the continental margins. In the left panel you can see a large intramountain basin (comparable to the Tarim Basin) developing within Asia when a <i>hard</i> lithospheric region in predefined within the continent. The amount of sediment trapped in it is very sensitive to climatic parameters, particularly to evaporation, because it crucially determines its endorheic/exorheic drainage. We identify a feedback between erosion and crustal thickening leading locally to a <50 at="" climatically-enhanced="" concentrated.="" corners="" deformation="" flank="" growing="" in="" increase="" indenter="" is="" of="" orographic="" p="" place="" places="" plateau="" precipitation="" preferentially="" rates="" specially="" syntaxes="" takes="" the="" this="" upwind="" where="">
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We hypothesize that this may provide clues for better understanding the mechanisms underlying the intriguing tectonic aneurysms documented in the Himalayas. At the continental scale, however, the overall distribution of topographic basins and ranges</div>
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seems insensitive to climatic factors, despite these do have important, sometimes counterintuitive effects on the amount of sediments trapped within the continent. The dry climatic conditions that naturally develop in the interior of the continent, for example, trigger large intra-continental sediment trapping at basins similar to the Tarim Basin because they determine its endorheic/exorheic drainage. These complex climatic-drainage-</div>
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tectonic interactions make the development of steady-state topography at the continental scale unlikely.</div>
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Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com0Asia34.047863 100.61965529999998-41.757562 -64.614719700000023 90 -94.145969700000023tag:blogger.com,1999:blog-4996769537501094384.post-70993981887305296742015-07-30T16:57:00.000+02:002015-09-05T17:46:07.319+02:00Erosion in northern Spain (Ebro Basin)The <a href="http://retosterricolas.blogspot.com/2015/07/evolucion-topografica-de-la-cuenca-del.html">previous post</a> dealt with the erosion of the Ebro Basin after its colmatation with sediment, about 10 million years ago. The journal <i><b>Geology</b></i> has just chosen the following picture to illustrate the <a href="http://geology.gsapubs.org/content/current">cover of their August volume</a>: <br />
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-WwJysVMMPJk/VZZ88rHTEZI/AAAAAAAAl5k/17kdWZTQpKE/s1600/Castildetierra%2BGeolodia%2BCarrion%2B-%2Bvi%25CC%2581a%2BJuan%2B-%2Bsmallest.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="640" src="http://1.bp.blogspot.com/-WwJysVMMPJk/VZZ88rHTEZI/AAAAAAAAl5k/17kdWZTQpKE/s640/Castildetierra%2BGeolodia%2BCarrion%2B-%2Bvi%25CC%2581a%2BJuan%2B-%2Bsmallest.jpeg" width="454" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i style="font-size: 12.8000001907349px; text-align: start;"><a href="https://www.google.es/maps/place/Castill+De+Tierra/@42.2129207,-1.5133588,13z/data=!4m2!3m1!1s0x0000000000000000:0x58cc3d58d2c3eb40">Castildetierra</a></i><span style="font-size: 12.8000001907349px; text-align: start;"> is one of the many hills sculpted by erosion of the ancient <br />sediment infill of the Ebro Basin at Bardenas Reales (Navarra, Spain). </span><br />
<span style="font-size: 12.8000001907349px; text-align: start;">Photo: <span style="background-color: white; color: #222222; font-family: arial, sans-serif; font-size: 12.8000001907349px; text-align: start;">Larrión & Pimoulier.</span><br />Location: <a href="https://www.google.es/maps/place/Castill+De+Tierra/@42.2129207,-1.5133588,13z/data=!4m2!3m1!1s0x0000000000000000:0x58cc3d58d2c3eb40">42.2103 N, 1.5157 W</a></span></td></tr>
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The soft alluvial clays that make most of this hill are interbedded with harder lacustrine limestones and fluvial sandstones. The same alternation prevails over much of the Ebro Basin (NE Spain). These strata record a 19-million-year-old lake and alluvial system in the centre of an endorheic Ebro basin (84,000 km2 in area). Subsequent basin capture and drainage integration towards the Mediterranean lead to erosional features like the one in the picture.<br />
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Despite the most recent sedimentary has been removed by erosion, <a href="http://geology.gsapubs.org/content/early/2015/06/23/G36673.1.abstract">our study</a> could date this major drainage change at 12.0-7.5 million years ago, based on isostatic modeling constrained with paleomagnetic data. In these badlands at Bardenas Reales (Navarra), high erosion rates have been measured in the order of millimeters per year, but how these rates link to the long-term history of the region is unclear. Other places in the basin show Pleistocene erosion rates in the order of 0.1-0.4 mm/yr, whereas <a href="http://retosterricolas.blogspot.com/2015/07/evolucion-topografica-de-la-cuenca-del.html">our results suggest</a> an average erosion rate since the Miocene of 0.05-0.1 mm/yr.<br />
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<b style="text-align: center;">Summary of the scientific <a href="http://geology.gsapubs.org/content/43/8/663.abstract">article in Geology</a></b><span style="text-align: center;">: Basins formed within mountainous regions often become perfect sedimentary traps that do not drain to the sea but to internal evaporitic lakes. When they do, their sediment layers ideally record the climatic, topographic, and tectonic history of the surroundings. And when these basins eventually overtop or overfill with sediment, they are rapidly excavated by the new outflowing fluvial network, exposing excellent stratigraphic outcrops. However, this erosion often removes the uppermost basin infill, and essential information about the late basin history is lost. We have estimated the timing and elevation of the maximum infill of the Ebro basin (NE Spain) by computing the rebound of the basin in response to erosion, adopting the common idea that the Earth's rigid outer shell (the lithosphere) rests on a fluid magmatic asthenosphere in an Archimedes-type equilibrium (</span><i style="text-align: center;"><a href="http://retosterricolas.blogspot.com/2012/09/see-lithosphere-moving-up-and-down.html">isostasy</a></i><span style="text-align: center;">). We combine these calculations with existing paleomagnetic ages of the sediment basin infill. The results show that the basin became overfilled between 12 and 7.5 million years ago, and that it reached a maximum elevation of up to 750 m above present sea level. The basin has been ever since incised at a rate close to 0.1 mm/yr and has been isostatically uplifted by up to 630 m at its center. This uplift may explain why the Ebro River, opposite to other large Mediterranean rivers, does not present a deep gorge excavated within its own basin during the desiccation of the Mediterranean (Messinian salinity crisis, 5.5 million years ago).</span></div>
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Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com022251 Alcubierre, Huesca, Spain41.808249 -0.4537748000000192441.796413 -0.47394480000001926 41.820085000000006 -0.43360480000001922tag:blogger.com,1999:blog-4996769537501094384.post-9967844207783186502015-07-30T13:32:00.000+02:002015-07-30T18:16:50.926+02:00Evolución topográfica de la Cuenca del Ebro<div class="separator" style="clear: both; text-align: center;">
<span style="font-size: x-small;">[Este post hace divulgación de un trabajo que acabamos de <a href="http://geology.gsapubs.org/content/early/2015/06/23/G36673.1.abstract">publicar en <i>Geology</i></a>] </span></div>
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<span style="font-size: x-small;">[This is outreach material about our own research, now <a href="http://geology.gsapubs.org/content/early/2015/06/23/G36673.1.abstract">published in <i>Geology</i></a>] </span></div>
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<span style="font-size: x-small;">[see also <a href="http://retosterricolas.blogspot.com/2015/07/erosion-in-northern-spain-ebro-basin.html">this post about the cover of the August volume of <i>Geology</i></a>]</span></div>
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Viajando entre Navarra y Lleida habrás reparado seguramente en las capas casi horizontales de sedimento, omnipresentes en la Cuenca del Ebro. Se trata de sedimento depositado en el fondo de lagos y en ríos durante el Mioceno (hace entre 24 y 5 millones de años), proveniente de la erosión del Pirineo y, en menor medida, del Sistema Ibérico y la Cordillera Costero-Catalana.<br />
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<tr><td><a href="http://2.bp.blogspot.com/-rq4jhVb_6nI/VVtEZL1KfrI/AAAAAAAAkXI/iJM5AwSaWts/s1600/20141222_125749%2Bcrop.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="212" src="http://2.bp.blogspot.com/-rq4jhVb_6nI/VVtEZL1KfrI/AAAAAAAAkXI/iJM5AwSaWts/s640/20141222_125749%2Bcrop.jpeg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8000001907349px;">1. Vista desde la cima de San Caprasio (Zaragoza), en el centro de la Cuenca del Ebro (cubierta por las nubes). A la derecha aparecen los sedimentos calcáreos más modernos preservados en la cuenca, datados en 13.6 millones de años. Foto: DGC.</td></tr>
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<tr><td style="text-align: center;"><a href="http://www.turismodigital.com/fotos/parque-natural-de-las-bardenas-reales-navarra-1-501.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://www.turismodigital.com/fotos/parque-natural-de-las-bardenas-reales-navarra-1-501.jpg" height="220" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8000001907349px; text-align: center;">2. Bardenas Reales (Navarra). Foto: PN Bardenas.</td></tr>
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<tr><td style="text-align: center;"><a href="https://upload.wikimedia.org/wikipedia/commons/0/08/Bardeak.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="Soft alluvial clays interbedded with harder lacustrine limestones and fluvial sandstones predominate over much of the Ebro Basin in NE Spain. In these badlands at Bardenas Reales (Castildetierra, Navarra), high erosion rates have been measured in the order of millimeters per year, but how these rates link to the long-term history of the basin is unclear. These strata record a 15-million-years-old lake and alluvial system in the centre of an endorheic Ebro basin (84,000 km2 in area). Subsequent basin capture and drainage integration towards the Mediterranean lead to erosional features like the one in the picture. Our study dates this major drainage change at 12.0-7.5 million years ago. Location: 42.2103 N, 1.5157 W" border="0" height="320" src="https://upload.wikimedia.org/wikipedia/commons/0/08/Bardeak.jpg" title="" width="212" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8000001907349px; text-align: center;"><span style="font-size: 12.8000001907349px; text-align: right;">3. La roca calcárea en lo alto del</span><br />
<span style="font-size: 12.8000001907349px; text-align: right;">Cabezo de Castildetierra </span><span style="font-size: 12.8000001907349px; text-align: right;">(Bardenas </span><br />
<span style="font-size: 12.8000001907349px; text-align: right;">Reales, Navarra) </span><span style="font-size: 12.8000001907349px; text-align: right;">apenas protege a </span><br />
<span style="font-size: 12.8000001907349px; text-align: right;">las margas </span><span style="font-size: 12.8000001907349px; text-align: right;">de la erosión. Esas calizas </span><br />
<span style="font-size: 12.8000001907349px; text-align: right;">se formaron en los lagos que </span><span style="font-size: 12.8000001907349px; text-align: right;">ocupaban </span><br />
<span style="font-size: 12.8000001907349px; text-align: right;">la Cuenca del </span><span style="font-size: 12.8000001907349px; text-align: right;">Ebro hace entre 36 y 10 </span><br />
<span style="font-size: 12.8000001907349px; text-align: right;">millones de años. </span><span style="font-size: 12.8000001907349px; text-align: right;">Foto: Carlos Sancho</span></td></tr>
</tbody></table>
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
Ese sedimento contiene importantes cantidades de yeso recristalizado (CaSO4·2H2O, Imagen 4), proveniente de la disolución de yesos más antiguos en el Pirineo. La acumulación de estas rocas evaporíticas indica que ese antiguo sistema de lagos del centro de la cuenca carecía de desaguadero, es decir, era un sistema <i>endorreico</i> en el que todo el agua recogida acababa siendo evaporada.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-n8MP-IYnbtY/VVtAGdB9c8I/AAAAAAAAkW0/z76NeRjUwrk/s1600/20141222_112913.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="240" src="http://2.bp.blogspot.com/-n8MP-IYnbtY/VVtAGdB9c8I/AAAAAAAAkW0/z76NeRjUwrk/s320/20141222_112913.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8000001907349px; text-align: center;">4. Yeso cristalizado visible en los niveles intermedios de San<br />
Caprasio. <span style="font-size: 12.8000001907349px;">Unos 18 millones de años de edad. Foto: DGC </span></td></tr>
</tbody></table>
Tras ese largo periodo endorreico, el sistema lacustre rebosó o resultó colmatado de sedimento, formándose el actual río Ebro, que ha erosionado y transportado al delta más de 30,000 km3 del antiguo relleno de la Cuenca del Ebro. Hoy, el sedimento preservado más elevado está precisamente en la zona central de la misma, en la Sierra de Alcubierre, 20 km al este de Zaragoza y a 840 m sobre el nivel del mar (Imagen 1).<br />
¿Porqué están más altos esos sedimentos en el centro de la cuenca, si los lagos deberían ocupar la zona topográficamente más baja? ¿Y porqué no rebosaron antes los lagos hacia el Mediterráneo, si la actual divisoria de la cordillera Costero-Catalana tiene lugares de menos de 500 m de altitud?<br />
<br />
En ausencia de deformación tectónica (las cadenas montañosas circundantes ya se habían acabado de formar), los movimientos verticales de la superficie de la Tierra están generalmente relacionados con la <i><a href="http://retosterricolas.blogspot.com/search/label/isostasy">isostasia</a>:</i> La erosión de la cuenca del Ebro supuso una <i>descarga</i> y un levantamiento (<i>un rebote isostático</i>) de la litosfera terrestre, que descansa sobre el manto como si se tratara de un iceberg en el océano.<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td><a href="http://4.bp.blogspot.com/-wWnpoihA-kA/VVsoRvhBQRI/AAAAAAAAkWk/u2PNeW5YdnE/s1600/local-regional%2Bisostasy%2B-%2Bflexure%2C%2Belastic%2Bthickness.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="291" src="http://4.bp.blogspot.com/-wWnpoihA-kA/VVsoRvhBQRI/AAAAAAAAkWk/u2PNeW5YdnE/s320/local-regional%2Bisostasy%2B-%2Bflexure%2C%2Belastic%2Bthickness.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8000001907349px;">5. Hundimiento isostático que sufre la litosfera (en gris) sobre la<br />
astenosfera fluida (blanco) cuando sobre ella descansa una carga (verde),<br />
para 4 escenarios en los que la litosfera es progresivamente más delgada y débil.<br />
En el escenario de una litosfera muy gruesa y rígida no se producen movimientos verticales<br />
de reajuste. En el caso más débil, cada columna del sistema se reajusta localmente y<br />
tiene el mismo peso si se mide hasta un nivel de compensación en la astenosfera. Autor: DGC</td></tr>
</tbody></table>
En nuestro <a href="http://geology.gsapubs.org/content/early/2015/06/23/G36673.1.abstract">artículo</a> de esta semana, hemos calculado estos movimientos verticales de la litosfera terrestre para poder estimar el volumen de sedimento erosionado que falta en la cuenca del Ebro. Comparándolo con el volumen actualmente acumulado en el delta del Ebro, hemos podido establecer la edad en la que se produjo la colmatación, el relleno máximo de la cuenca, entre 7.5 y 12.0 millones de años, así como la altitud original que alcanzó la cuenca: 535–750 m sobre el nivel actual del mar.<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-uyr7NkB_NJE/VNTNGDI2AnI/AAAAAAAAg8Q/BNyczzczwMw/s1600/animated.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="640" src="http://3.bp.blogspot.com/-uyr7NkB_NJE/VNTNGDI2AnI/AAAAAAAAg8Q/BNyczzczwMw/s1600/animated.gif" width="624" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8000001907349px; text-align: center;">6. Animation (reload page if necessary): Estimated topographic evolution of the Ebro Basin <span style="font-size: 12.8000001907349px;">(NE, Spain) </span><span style="font-size: 12.8000001907349px;">since 10 million years ago until present</span><br />
<br /></td></tr>
</tbody></table>
<br />
<br />
<br />
<br />
<iframe frameborder="0" height="480" src="https://earthengine.google.org/timelapse/player?c=https%3A%2F%2Fearthengine.google.org%2Ftimelapse%2Fdata&v=42.34116,-120.89296,6.5&r=1&p=true" width="854"></iframe>7. Las cuencas endorreicas (zonas que no drenan sus aguas al mar) suelen presentar sistemas lacustres que son extremadamente sensibles a las variaciones climáticas, pues en ellos la superficie lacustre se debe adaptar para compensar la lluvia recogida con la evaporación en su superficie.Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com0Alcubierre, Huesca, Spain41.733480894298687 -0.4633878371093942441.638726394298686 -0.62474933710939418 41.828235394298687 -0.30202633710939425tag:blogger.com,1999:blog-4996769537501094384.post-642259070295653792015-03-26T09:00:00.000+01:002015-03-28T00:02:31.474+01:00Microblogs will not become a source of scientific knowledge<span style="background-color: white; color: #333333; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 14px; line-height: 20px;">This is the contribution I submitted to the newly created </span><span style="background-color: white; color: #333333; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 14px; line-height: 20px;"><i><a href="http://beta.briefideas.org/">Journal of Brief Ideas</a></i>, which defines itself as a <i>research journal </i>exclusively for articles of 200 words or less: </span><br />
<blockquote class="tr_bq">
<span style="color: #333333; font-family: Helvetica Neue, Helvetica, Arial, sans-serif;"><span style="font-size: 14px; line-height: 20px;"><b>Title: Microblogs will not become a source of scientific knowledge</b></span></span></blockquote>
<blockquote class="tr_bq">
<span style="background-color: white; color: #333333; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 14px; line-height: 20px;">The hypothesis that scientific knowledge can grow out of clearly-written ideas capsuled in 200 words with no antecedents, no references, no methods, and no results, is contradictory with the notion of science itself and therefore does not need to be refuted. However, the profusion of microblogging social networks that may be tempted to introduce DOI's as a way to make their tweets and posts citable, threatens to blur the boundaries with other sources of knowledge. Here, I expose the following brief ideas: 1) that any useful contribution to discern ideas that work from ideas that don't, will need, also in the future, enough words to describe how those ideas were tested; 2) that the routine activity of both scientists and non-scientists will tend to keep discerning the systematic, reproducible studies from bar conversations, online forums, and magically-revealed knowledge; and 3) that consequently the present brief, unreferenced publication will get no credit, even if it turns out to be the first to correctly predict the fail of short unreferenced notes as a source of scientific knowledge. </span><span style="background-color: white; color: #333333; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 14px; line-height: 20px;">And yet, my last 20 available words call for further transgressive ideas for this field, scientific publishing, that will be hardly recognisable in a decade.</span></blockquote>
<br />
Sadly enough, the editors have not accepted this 'article' for their 'beta journal', on the basis of a <i>lack of a scientific advance in the field</i>:<br />
<blockquote class="twitter-tweet" lang="en"><p><a href="https://twitter.com/danigeos">@danigeos</a> It was more of an opinion piece than something that advances the state of research in a field, as required by our guidelines.</p>— Journal Brief Ideas (@BriefJournal) <a href="https://twitter.com/BriefJournal/status/571353268598624256">February 27, 2015</a></blockquote>
<script async src="//platform.twitter.com/widgets.js" charset="utf-8"></script>
And I fully agree with their point. All they will attract is ideas, hypotheses, opinions; Scientific advance is much more than that and it will not be achieved in the format proposed. And to be consistent, the Journal of Brief Ideas should either ban most of the contributions they receive (<a href="http://beta.briefideas.org/ideas/17b997da912f99ce9988a47f42b52692">like this</a>) or stop calling itself a scientific journal. <b>It is the reputation of the <i>scientific method</i> (slippery as this can be) that is at risk.</b>
<blockquote class="twitter-tweet" lang="en"><p>.<a href="https://twitter.com/BriefJournal">@briefjournal</a> It is not possible to advance th state of any field without that. That was th point of this 'idea' that u dont seem 2 approve</p>— ∆ Garcia-Castellanos (@danigeos) <a href="https://twitter.com/danigeos/status/571374456377090048">February 27, 2015</a></blockquote>
<script async src="//platform.twitter.com/widgets.js" charset="utf-8"></script>
Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com0tag:blogger.com,1999:blog-4996769537501094384.post-11522285193028454482015-03-25T16:23:00.000+01:002015-04-24T09:15:42.913+02:00Wiki Loves Earth 2015: Wikipedia, Geociencia y Biología<div class="separator" style="clear: both; text-align: center;">
</div>
<div class="separator" style="clear: both; text-align: center;">
<a href="http://1.bp.blogspot.com/-bf7ChcTswFc/VRcaA48LzgI/AAAAAAAAhuM/tBKYp3Olrzc/s1600/Cartel%2BWLE-1024.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><br /></a><a href="http://1.bp.blogspot.com/-bf7ChcTswFc/VRcaA48LzgI/AAAAAAAAhuM/tBKYp3Olrzc/s1600/Cartel%2BWLE-1024.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="http://1.bp.blogspot.com/-bf7ChcTswFc/VRcaA48LzgI/AAAAAAAAhuM/tBKYp3Olrzc/s1600/Cartel%2BWLE-1024.jpg" height="320" width="240" /></a></div>
<b>[Viernes 24 de abril de 2015, <a href="https://www.facebook.com/events/863979623640342/">conferencia sobre este tema en Barcelona</a>]</b><br />
<br />
Wikimedia (la fundación que da soporte a Wikipedia y sus <a href="https://www.wikimedia.org/">proyectos hermanos</a>) está organizando el <b>concurso internacional de fotografía <a href="http://www.wikilovesearth.es/">Wiki Loves Earth</a></b>, que premiará las mejores fotografías de espacios naturales catalogados con el fin de ilustrar artículos de Wikipedia y quedar disponibles en la red para su uso gratuito. El concurso nació en Ucrania en 2013, inspirado por el éxito de <a href="http://www.wikilovesmonuments.org/" style="font-style: italic;">Wiki Loves Monuments</a> (el mayor concurso fotográfico de la historia), y actualmente está organizado por las representaciones locales de Wikimedia (Wikimedia-España, Wikimedia-Argentina, etc) en más de 20 países, pudiéndose participar de forma gratuita. En España, los lugares fotografiados deben ser espacios naturales reconocidos como <a href="http://es.wikipedia.org/wiki/Lugar_de_importancia_comunitaria">Lugares de Importancia Comunitaria</a> por la <a href="http://www.magrama.gob.es/es/biodiversidad/temas/espacios-protegidos/red-natura-2000/lic.aspx">red Natura 2000</a>. Las fotografías no tienen porqué ser recientes, pero se deben presentar entre el 1 y el 31 de mayo de 2015. Para participar, basta con registrarse gratuitamente en <a href="https://commons.wikimedia.org/">Wikimedia Commons</a> o en el <a href="http://www.flickr.com/groups/wle2015/">grupo de Flickr</a> creado al efecto y subir las fotos que quedarán públicamente accesibles e indexadas bajo una licencia libre. En cada país, un jurado compuesto por personas relacionadas con la naturaleza, la fotografía y el conocimiento libre otorgará varios premios, y las diez mejores fotografías de cada país participarán en la fase internacional del concurso, con sus propios premios. Para facilitar la localización de los Lugares de Importancia Comunitaria Wikimedia España ha creado <a href="http://www.wikilovesearth.es/es/Wiki_Loves_Earth/Listado">listados de los mismos en cada comunidad autónoma</a>, cada una de ellas con un mapa propio.<br />
<div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://commons.wikimedia.org/wiki/File:%D0%9A%D0%B0%D1%80%D0%BF%D0%B0%D1%82%D1%81%D0%BA%D0%B8%D0%B9_05.jpg" style="margin-left: auto; margin-right: auto;"><img src="http://upload.wikimedia.org/wikipedia/commons/thumb/2/28/%D0%9A%D0%B0%D1%80%D0%BF%D0%B0%D1%82%D1%81%D0%BA%D0%B8%D0%B9_05.jpg/1280px-%D0%9A%D0%B0%D1%80%D0%BF%D0%B0%D1%82%D1%81%D0%BA%D0%B8%D0%B9_05.jpg" height="426" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: xx-small; text-align: start;">Fotografía ganadora a nivel internacional en la edición de 2014 de Wiki Loves Earth. Parque Nacional de los Cárpatos, ubicado en el monte Goverla. Ivano-Frankivsk Oblast, Ucrania. Por Balkhovitin (CC-BY-SA 3.0).</span></td></tr>
</tbody></table>
¿Y qué tiene que ver esto con la Tierra Sólida, la geociencia o la biología? Pues ésta puede ser una oportunidad para difundir el trabajo de campo que llevamos a cabo los geocientíficos (y biólogos) de todas las disciplinas. Las innumerables fotografías de campo que producimos cada año son casi siempre libres de derechos de autor y bien georeferenciadas, y son a menudo de calidad y de lugares poco accesibles o poco accedidos. Publicando estas fotografías en un repositorio libre como <i>Commons</i> no sólo llenamos sus vacíos geográficos sino que además aumentamos la presencia de nuestras disciplinas y zonas de estudio en la enciclopedia. Wikipedia, y particularmente su versión en español, es <b>pobre en artículos sobre geología y Ciencias de la Tierra</b>. Por ejemplo, hay 6 veces más artículos buenos o destacados en la categoría <i>Historia de España</i> que en <i>Ciencias de la Tierra</i>. Ignoro si esto es la causa o un reflejo del flojo reconocimiento que hace nuestra comunidad científica a Wikipedia, ese proyecto que nació hace 14 años revolucionando para siempre la compilación y el acceso al conocimiento.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><img border="0" height="265" src="https://upload.wikimedia.org/wikipedia/commons/8/87/Amanhecer_no_Hercules_--.jpg" style="margin-left: auto; margin-right: auto;" width="400" /></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: #eeeeee; color: #666666; font-family: Georgia, serif; font-size: 12px; line-height: 19.5px; text-align: start;">Segundo premio de 2014: Serra dos Órgãos, Estado de Rio de Janeiro, por by Carlos Perez Couto.</span></td></tr>
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<a href="https://upload.wikimedia.org/wikipedia/commons/8/87/Amanhecer_no_Hercules_--.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"></a><br class="Apple-interchange-newline" /></div>
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Wikipedia es una enciclopedia en la que cualquiera puede editar y supervisar los contenidos buscando el consenso con otros editores, todos voluntarios. Cuanto mayor es el número de editores atraído por un artículo, más discusión y más robustas son las mejoras. Como en ciencia, el éxito de una modificación de los contenidos depende a menudo de citar una fuente fiable; pero en cambio en Wikipedia importa poco si quien incorpora un cambio es una autoridad reconocida en la materia o un amateur muy entusiasta. Y a pesar de ello los contenidos no han parado de mejorar en calidad con el tiempo. Cuando Wikipedia nació en 2001 pocos apostaron por el futuro de una enciclopedia sin una editorial centralizada escogida arbitrariamente para producir los contenidos. Hoy Wikipedia está entre las 6 webs más consultadas del planeta, con alrededor de <a href="http://stats.wikimedia.org/EN/TablesWikipediaZZ.htm#distribution">28 millones de artículos</a> de acceso gratuito sin publicidad, con más de 70.000 editores voluntarios activos (4.300 en español) que realizan 12 millones de ediciones cada mes, y hay estudios académicos que avalan la calidad de sus contenidos. Poner en duda el enorme impacto del movimiento wikipedista es hoy una osadía comparable a cuestionar la tectónica de placas.</div>
<br />
Aparte de #WikiLovesEarth, existen otros proyectos que intentan fomentar la mejora de artículos sobre Ciencias de la Tierra (por cierto el <a href="http://es.wikipedia.org/wiki/Wikiproyecto:Ciencias_de_la_Tierra">Wikiproyecto</a> está en peligro de caer inactivo), donde se pueden solicitar artículos que necesitan aún ser redactados o mejorados. O este <a href="http://es.wikipedia.org/wiki/Portal:Ciencias_de_la_Tierra"><b>Portal</b></a> en el que se divulgan los objetivos de esta rama de la ciencia, y que cualquier amante de la misma puede mejorar haciendo click en 'editar'. También han habido multitud de proyectos educativos que usan la Wikipedia como base para dar a los alumnos claves de estructuración y evaluación crítica de la información. O para fomentar la interacción entre ciencia y humanidades: aprovecho para compartir esta <a href="https://outreach.wikimedia.org/wiki/WikiArS/es">experiencia personal</a>.<br />
<br />
Video sobre cómo participar en WLE:<br />
<iframe src="https://commons.wikimedia.org/wiki/File%3AWiki_Loves_Earth_Espa%C3%B1a_-_C%C3%B3mo_participar.webm?embedplayer=yes" width="512" height="288" frameborder="0" ></iframe>
<br />
<br />
<span style="font-size: x-small;">Este artículo incluye extractos del artículo de <a href="https://commons.wikimedia.org/wiki/User:Poco_a_poco">Diego Delso</a>: <a href="http://blog.wikimedia.es/2015/03/wikimedia-espana-organiza-por-primera.html"><i>Wikimedia España organiza por primera vez Wiki Loves Earth</i></a>.</span></div>Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com0tag:blogger.com,1999:blog-4996769537501094384.post-18411850991447980802015-02-20T09:42:00.000+01:002015-08-26T15:14:19.779+02:00Atlantropa, the Messinian salinity crisis, and other Alternative Worlds<!--[if gte mso 9]><xml>
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<div class="Ao-entrada">
<span lang="X-NONE">Out of this age of crisis, a</span> book has just been published that aims at fully opening the doors of imagination to show how audacious we humans are when in need to restart from scratch:<br />
<br /></div>
<div class="Ao-entrada">
<i><a href="http://www.peterlang.com/index.cfm?event=cmp.ccc.seitenstruktur.detailseiten&seitentyp=produkt&pk=81532">Alternative Worlds, Blue-Sky thinking since 1900</a></i> <span style="font-size: x-small;">(R. Vidal & Cornils, eds.; Peter Lang Publishing,
Bern, ISSN 3034317875, 9783034317870)</span>. </div>
<div class="separator" style="clear: both; text-align: center;">
<a href="http://3.bp.blogspot.com/-HLhR_V4ihhc/VObnZGMWPLI/AAAAAAAAhGg/e76rq6To8DM/s1600/Alternative%2BWorlds%2BCover-front.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://3.bp.blogspot.com/-HLhR_V4ihhc/VObnZGMWPLI/AAAAAAAAhGg/e76rq6To8DM/s1600/Alternative%2BWorlds%2BCover-front.jpg" width="213" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
The book includes an article by the editor Ricarda Vidal (King’s College London) giving an updated perspective on the <i><a href="http://www.daviddarling.info/encyclopedia/G/Gibraltar_Cathcart.html">Atlantropa Project</a> </i>(1929). <i>Atlantropa</i> intended to reduce the area of the Mediterranean Sea by 30% by damming the Strait of Gibraltar, allowing natural evaporation to lower the sea level by a couple of hundred meters. With this project, Herman Sörgel sought to control the inflow of Atlantic seawater to generate electricity, to exposing new inhabitable land (former submarine continental shelf), and to use the Nile River to irrigate a vast part of the Sahara Desert.<br />
The project thus aimed at mimicking what nature did 6 million years ago during the <a href="http://retosterricolas.blogspot.com/search/label/Messinian">Messinian Salinity Crisis</a>, and that's why I coauthor with Vidal a second chapter dealing with what we know about this ancient salinization and desiccation of the Mediterranean from a scientific perspective, and about the footprint this geology left in western culture.<br />
The rest of the volume discusses fascinating Alternative Worlds including seasteads, planned cities, the high-rise age, and the promising worlds-to-be in the outer space.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<iframe width="320" height="266" class="YOUTUBE-iframe-video" data-thumbnail-src="https://i.ytimg.com/vi/IwxPvvcHIpc/0.jpg" src="https://www.youtube.com/embed/IwxPvvcHIpc?feature=player_embedded" frameborder="0" allowfullscreen></iframe></div>
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<div>
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<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
<strong>Part I: Shaping the Earth and Sea</strong></div>
<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
1. Ricarda Vidal: Atlantropa: One of the Missed Opportunities of the Future</div>
<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
2. Daniel Garcia-Castellanos/Ricarda Vidal: Alternative Mediterraneans Six Million Years Ago: A Model for the Future?</div>
<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
3. Philip E. Steinberg/Elizabeth A. Nyman/Mauro J. Caraccioli: Atlas Swam: Freedom, Capital and Floating Sovereignties in the Seasteading Vision</div>
<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
<br /></div>
<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
<strong>Part II: The 1960s – Building the Future</strong></div>
<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
4. Patricia Silva McNeill: The Last ‘City of the Future’: Brasília and its Representation in Literature and Film</div>
<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
5. Elena Solomides: The Post-War High-Rise: Promise of an Alternative World</div>
<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
6. Christopher Daley: ‘The landscape is coded’: Visual Culture and the Alternative Worlds of J.G. Ballard’s Early Fiction</div>
<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
<br /></div>
<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
<strong>Part II: Alternative Lives</strong></div>
<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
7. Maya Oppenheimer: Designed Surfaces and the Utopics of Rejuvenation</div>
<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
8. Boukje Cnossen: The Alternative World of Michel Houellebecq</div>
<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
9. Susanne Kord: From the American Myth to the American Dream: Alternative Worlds in Recent Hollywood Westerns</div>
<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
10. Marjolaine Ryley: Growing up in the New Age: A Journey into Wonderland?</div>
<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
<br /></div>
<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
<strong>Part IV: Outer Space</strong></div>
<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
11. Peter Dickens: Alternative Worlds in the Cosmos</div>
<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
12. Ingo Cornils: Between Bauhaus and <i>Bügeleisen</i>: The Iconic Style of <i>Raumpatrouille </i>(1966)</div>
<div style="background-color: white; color: #555555; font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 20.3999996185303px;">
13. Rachel Steward: Blue Sky Thinking in a Post-Astronautic Present.</div>
<div>
<br /></div>
<div style="text-align: center;">
<br /></div>
<ul style="font-family: sans-serif; font-size: 13px; line-height: 1.5em; list-style-image: url(http://bits.wikimedia.org/skins-1.17/monobook/bullet.gif); list-style-type: square; margin: 0.3em 0px 0.5em 1.5em; padding: 0px;">
<li><i style="font-family: Times; font-size: medium; line-height: normal;">Alternative Worlds, Blue-Sky thinking since 1900, </i><span style="font-family: Times; font-size: small; line-height: normal;">R. Vidal & Cornils (Peter Lang Publishing, Bern, ISSN 3034317875, 9783034317870).</span></li>
<li style="margin-bottom: 0.1em;">R.B. Cathcart, "What if We Lowered the Mediterranean Sea?", Speculations in Science and Technology, 8: 7-15 (1985).</li>
</ul>
Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com0tag:blogger.com,1999:blog-4996769537501094384.post-38068120753736052482015-01-14T16:51:00.009+01:002023-01-05T10:33:12.476+01:00Scientist evaluation, the h index, and the #PaperBubble<span style="font-size: x-small;">[A bit of self-criticism on the science evaluation system, just to start the year.]</span><br />
<br />
Wicked rules can pervert a community.<br />
In science, the pioneer wicked rule was evaluating scientists for <b>how much</b> we published, how many papers we coauthored regardless of our real contribution to them, and <b>in what journals</b> do we publish, as a proxy for quality or merit. If you coauthor many articles in good (very cited) journals then you must be a good scientist, that was the institutional <i>mantra</i>. The basic underlaying assumption was that the citations to someone's work by other scientists are a good measure of the importance of her/his research, and I will not question this here. But in this century, to measure the importance of someone's work, we don't need impact factors anymore and we don't need to care about what journal hosts the article in question, because individual citations to each individual article are accessible in a few clicks.<br />
Evaluating by the “mere number of a researcher’s publications” disincentivized risky and potentially-ground-breaking research lacking a short-term publication outcome, as the editor of <i>Science</i> <a href="http://www.bumc.bu.edu/busm-pm/files/2013/05/Science-2013-Alberts-787.pdf">argue</a>s. But this is what was being done. And as a result, the scientific articles published every year have nearly <a href="https://thewinnower.com/papers/the-rising-trend-in-authorship">tripled since 1990</a>.<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-4beCwRFfft0/VEqUQdNg1SI/AAAAAAAAdmo/EP2DRFffsW0/s1600/global%2Bpapers%2Bper%2Byear.png" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="232" src="https://1.bp.blogspot.com/-4beCwRFfft0/VEqUQdNg1SI/AAAAAAAAdmo/EP2DRFffsW0/s320/global%2Bpapers%2Bper%2Byear.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Cumulative number of papers<br />
published in Biomedicine<br />
(source: PubMed via <a href="https://thewinnower.com/papers/the-rising-trend-in-authorship">this</a>)</td></tr>
</tbody></table>
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The same has happened in most countries and in most disciplines, although some have moved much faster than the average, look :-)<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-Rxmv4B5Q0M4/YTi0PtzM3MI/AAAAAAABITY/HQtVjMxE34gikw1FApGv6YSha-ad1gm0QCNcBGAsYHQ/s259/download.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="195" data-original-width="259" height="241" src="https://1.bp.blogspot.com/-Rxmv4B5Q0M4/YTi0PtzM3MI/AAAAAAABITY/HQtVjMxE34gikw1FApGv6YSha-ad1gm0QCNcBGAsYHQ/w320-h241/download.png" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td class="tr-caption">Annual number of papers in Yoga studies over time.<br /></td></tr></tbody></table></td></tr></tbody></table><br /><div>
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Does this mean that our science is now three times better? Does it mean that our understanding of Nature grows 3 times faster than 25 years ago? 10 times, in the case of Yoga? Mmm. It does mean that now we can only track a small fraction of all the papers that are relevant to our research. </div>
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<tr><td><a href="http://3.bp.blogspot.com/-uRNrFSXmer4/VEppPeNr7cI/AAAAAAAAdmU/18szfA95euQ/s1600/paper%2Bbubble.bmp" style="margin-left: auto; margin-right: auto;"><img border="0" height="220" src="https://3.bp.blogspot.com/-uRNrFSXmer4/VEppPeNr7cI/AAAAAAAAdmU/18szfA95euQ/s1600/paper%2Bbubble.bmp" width="320" /></a></td></tr>
<tr><td class="tr-caption"><span face=""arial" , "helvetica" , sans-serif" style="background-color: white; font-size: xx-small; line-height: 23.8px;">[By Zhou Tao/Shanghai Daily] </span><br />
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Needless to say, this has yet another additional price for all of us:</div>
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<a href="http://geolog.egu.eu/wp-content/uploads/2014/10/pic2.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="266" src="https://geolog.egu.eu/wp-content/uploads/2014/10/pic2.png" width="320" /></a></div>
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To compensate for the perversion inherent to this article-count approach, evaluators started weighting that number with something called <i>Journal Impact Factor, </i>assuming that articles published in highly cited journals have a higher, statistically-sound chance to have an impact. Perfect plot for a self-accomplishing prophecy; The <a href="http://www.bumc.bu.edu/busm-pm/files/2013/05/Science-2013-Alberts-787.pdf">warnings against this practice are a clamor</a>. <br />
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Then </span>citation databases went online and another wicked parameter came on the scene:<br />
<b><i>h</i></b>, the <a href="https://en.wikipedia.org/wiki/H-index"><i>Hirsch</i> index</a>, was adopted in the last decade to come over the <i>number</i> <i>of publications</i> criterion. It has now become a commonplace in the evaluation of proposals. But <b><i>h</i> keeps overvaluing multi-authored papers beyond reason</b>, because it disregards the number of authors and their relative contribution (in most research areas, the relative scientific contribution of the authors of a paper can be approximated in first approach by the position in the author list). The citations to an article of yours count equally if you are the 1st author or the 100th. Therefore, a paper with 100 authors has 100 times more impact on the evaluation system that a single-authored paper. And I'm not being rhetorical here. Please, meet two of the highest-<i>h </i>scientists in Spain (just an example):<br />
Profile 1: <a href="http://scholar.google.es/citations?user=ar9Bk8gAAAAJ&hl=en">61k citations, 137 papers in 2013 only, h=112</a>.<br />
Profile 2: <a href="http://scholar.google.com/citations?user=-g21rBUAAAAJ&hl=es">117k citations, 164 papers in 2013 only, h=75</a>.<br />
I leave it to you finding the flaw.<br />
<br />
<div>Say you are part of a group of 100 friends, each leading his/her own paper and incorporating the other 99 as coauthors. Each citation to any of those 100 papers will reward 100 more people than citing a lonely author. Imagine now that each of them cites each other's paper. They immediately obtain 100 citations per paper. Not bad. It may seem this is a problem with self-citation that can be filtered easily, but it goes far beyond that. The 100 will still be rewarded beyond reason even if their citations come from someone else. Imagine that another group of 100 authors cites all your 100 papers as well as the lonely author's paper. This will give 100 citations to the single author but 10,000 citations to all others. Note that, if this were the first articles for all of them, then the single author would now be h=1, while all other have been miraculously promoted to h=100. </div><div><br /></div><div>This problem could be easily solved by weighting each author by 1/2^i , where i is the position of each author in the list. Because</div><div><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwWtWVZLpchBKmPzt7b8AhG6S_fpPRVnDZOhAI44EWyGNp5M1QpbEXUt2YMGimdtLwuaeqJvISLQlKSH2Efkk__IczRzQqmzV9tnk1iLO_u8Uo2D-udnkpJG5yq-tv2WmouXhgh1_8b0fF0WrIQV0p9MGhjihiqKHABYMBGWO97yq_EUAEL91jWPny_A/s576/Screenshot%202022-03-29%20at%2018.18.05.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="109" data-original-width="576" height="61" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwWtWVZLpchBKmPzt7b8AhG6S_fpPRVnDZOhAI44EWyGNp5M1QpbEXUt2YMGimdtLwuaeqJvISLQlKSH2Efkk__IczRzQqmzV9tnk1iLO_u8Uo2D-udnkpJG5yq-tv2WmouXhgh1_8b0fF0WrIQV0p9MGhjihiqKHABYMBGWO97yq_EUAEL91jWPny_A/s320/Screenshot%202022-03-29%20at%2018.18.05.png" width="320" /></a></div><br /><div>, the weight of all papers would be equal in the citation system. For this, the remainder of the series must be given to the last author, which in practice implies that the last 2 authors get the same credit. Definitely, much fairer than giving all authors a weight of one.</div><div><br /></div><div>But this was not done. Seemingly, decision makers were not interested in implementing anything like that.</div><div><br /></div><div>Very predictably, <b>the number of authors per paper just rocketed</b>, and former research groups have often become author pools, with the entire group signing every paper published by each of its members. A symptom of this is that few researchers dare to publish on their own today:</div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="clear: right; float: left; margin-bottom: 1em; margin-right: 1em;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-fRWlo2bJ4tw/VEqUQH46axI/AAAAAAAAdmk/qxbK2QIXKno/s1600/authors%2Bper%2Bpaper%2Bevolution.png" style="margin-left: auto; margin-right: auto;"><img border="0" height="232" src="https://1.bp.blogspot.com/-fRWlo2bJ4tw/VEqUQH46axI/AAAAAAAAdmk/qxbK2QIXKno/s1600/authors%2Bper%2Bpaper%2Bevolution.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 13px; text-align: center;">Average number of authors per paper during the<br />
last 100 years.<br />
<a href="https://thewinnower.com/papers/the-rising-trend-in-authorship">Source</a>: PubMed</td></tr>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-S9opZn6qJEU/VEqUPxrNuuI/AAAAAAAAdmg/3odmdTor_x0/s1600/average_authors_per_year.png" style="margin-left: auto; margin-right: auto;"><img border="0" height="115" src="https://4.bp.blogspot.com/-S9opZn6qJEU/VEqUPxrNuuI/AAAAAAAAdmg/3odmdTor_x0/s200/average_authors_per_year.png" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.7273px; text-align: center;">% of single-authored papers<br />
over the last century. </td></tr>
</tbody></table>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-ezZbKNOabmE/VEqURNUXpbI/AAAAAAAAdmw/d_RMxSbM6z4/s1600/papers%2Bper%2Byear%2Bper%2Bcountry.jpg" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto; text-align: center;"><img border="0" height="316" src="https://1.bp.blogspot.com/-ezZbKNOabmE/VEqURNUXpbI/AAAAAAAAdmw/d_RMxSbM6z4/s1600/papers%2Bper%2Byear%2Bper%2Bcountry.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Papers published per year. <a href="http://conversableeconomist.blogspot.com/2012/01/us-science-needs-to-look-beyond-our.html">Source</a></td></tr>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-VdULNcRplzs/VFGSBGbSbeI/AAAAAAAAdzc/c9IfCh2ILFg/s1600/scientists%2Bpublishing%2Brate%2Bbefore%2Band%2Bafter%2Bquitting%2B-%2Bcombined_JourAndConf%2B-%2Bcrop.png" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://2.bp.blogspot.com/-VdULNcRplzs/VFGSBGbSbeI/AAAAAAAAdzc/c9IfCh2ILFg/s400/scientists%2Bpublishing%2Brate%2Bbefore%2Band%2Bafter%2Bquitting%2B-%2Bcombined_JourAndConf%2B-%2Bcrop.png" width="122" /></a></td></tr>
<tr><td class="tr-caption">The left bar indicates the average number of <br />
articles published by authors that stopped <br />
publishing 15 years after their first publication. <br />
The blue bar on the right shows the articles <br />
published in the same timespan but by <br />
researchers that continued publishing after 15 <br />
years. The red bar on top indicates the articles of <br />
those same researchers after the 15th year. One <br />
can see that the researchers that continue <br />
publishing are those having a high research <br />
output. It also shows that the research output <br />
before the year break is the portion that <br />
contributes most to the overall values. <a href="http://ml.sun.ac.za/2012/12/06/trend-anomaly-in-academic-publication-data/">Source</a></td></tr>
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So the drive to scientific publication is still based on quantity, not quality.<br />
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Ask any editor how many of their requests to review a manuscript are refused by peers, and you'll learn that they often end up doing the reviews themselves. Too many papers for such few reviewers/authors. It is unsurprising that you find funny <a href="http://www.vox.com/xpress/2014/11/12/7211131/proofreading-crappy-paper">bugs like this</a> in articles that were supposed to have been reviewed.<br />
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It is difficult to find objective (quantitative) criteria for quality. And perhaps it is also time to question the trust on <i>objective parameters</i>. Alternatives such as interpreting the subjective impact foreseen for a given research <a href="http://www.sciencemag.org/content/340/6138/1265">are also risky</a>. But if the citation criterion is to be adopted, then <b>we do not need <i>h</i>-like indexes or journal impact factors</b>. <b>There are better metrics proposed (<a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1769438/">examples</a>), they just need to be adopted</b>. Metrics accounting for the author order and the number of coauthors.<br />
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Under the present rules, young researchers are pressed to publish as much as possible instead of publishing as good as possible, <b>not only perverting the research system but also inflating a huge publication bubble</b>. The warning lights are long on. <a href="http://english.cas.cn/newsroom/china_research/201109/t20110926_75603.shtml">China has already realized</a> the problem and may be soon taking <a href="http://www.nature.com/news/2011/110720/full/475267a.html">action</a>. Why not Europe? Will we wait until this bubble bursts?<br />
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Wicked rules pervert communities, so let's just adopt better rules. In 10 years the science publishing panorama will be unrecognizable anyway.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="color: #222222; font-family: arial; font-size: small; margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-NyzJy2aPr_8/VG2vmqa8VSI/AAAAAAAAeDI/IIGORbZbN9E/s1600/science%2Bpublication%2Bopen%2Baccess%2Bpaperbubble%2Binfographic%2Bxkcd%2B.jpg" style="margin-left: auto; margin-right: auto;"><img border="0" height="353" src="https://1.bp.blogspot.com/-NyzJy2aPr_8/VG2vmqa8VSI/AAAAAAAAeDI/IIGORbZbN9E/s1600/science%2Bpublication%2Bopen%2Baccess%2Bpaperbubble%2Binfographic%2Bxkcd%2B.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Source: <i><a href="http://www.sciencemag.org/content/342/6154/58.full">Science Mag</a>. </i></td></tr>
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PD: Interesting discussion in the comment section of this <a href="https://www.nature.com/articles/517245a">column in last week's Nature</a>.<br />
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PD2: Ironically, a journal called <a href="http://www.maneyonline.com/loi/bub">Bubble Science</a> just went closed earlier this year.<br />
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PD3: A new metric proposed: Author Impact Factor: tracking the individual scientific impact, by Kumar Pan & Fortunato. <a href="http://www.nature.com/articles/srep04880">link</a><br />
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PD4: A new journal now allows publishing <a href="http://www.nature.com/news/journal-publishes-200-word-papers-1.16925">citable articles of less than 200 words</a> with a DOI. What next? Citable tweets?</div>
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<a href="https://pbs.twimg.com/media/B_J8YYGU0AEQNkv.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="219" src="https://pbs.twimg.com/media/B_J8YYGU0AEQNkv.jpg" width="640" /></a></div>
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PD5: A paper reinventing the trapezoidal rule <a href="https://t.co/CANpYZ8GkX">https://t.co/CANpYZ8GkX</a> published in high-impact journal & has 268 citations <a href="https://t.co/ECI04VaoQ3">pic.twitter.com/ECI04VaoQ3</a> — ∆ Garcia-Castellanos (@danigeos) <a href="https://twitter.com/danigeos/status/692708786117726209">January 28, 2016</a><br />
<script async="" charset="utf-8" src="//platform.twitter.com/widgets.js"></script>
</div><div><br /></div><div>PD6: A PosOne paper by V. Vavryčuk including some references on this: "Fair ranking of researchers and research teams" <a href="https://dx.plos.org/10.1371/journal.pone.0195509">https://dx.plos.org/10.1371/journal.pone.0195509</a>.</div><div><br /></div><div>PD2022: China is now the first country by number of peer review publications as well as by <a href="https://www.science.org/content/article/china-rises-first-place-most-cited-papers">most-cited articles</a>. Thousands of scientists publish <a href="https://www.nature.com/articles/d41586-018-06185-8">a paper every 5 days</a> and t<span style="color: #0f1419; font-family: inherit; font-size: inherit; font-style: inherit; font-variant-caps: inherit; white-space: inherit;">he number of such authors has multiplied by 20 over 15 years</span><a class="css-4rbku5 css-18t94o4 css-1dbjc4n r-1loqt21 r-1pi2tsx r-1ny4l3l" href="https://twitter.com/danigeos/status/1583369138504073217/photo/1" role="link" style="-webkit-box-align: stretch; -webkit-box-direction: normal; -webkit-box-orient: vertical; align-items: stretch; border: 0px solid black; box-sizing: border-box; cursor: pointer; display: inline !important; flex-basis: auto; flex-direction: column; flex-shrink: 0; font-family: inherit; font-size: inherit; font-stretch: inherit; font-style: inherit; font-variant-caps: inherit; height: 317.2610168457031px; line-height: inherit; list-style: none; margin: 0px; min-height: 0px; min-width: 0px; outline-style: none; padding: 0px; position: relative; text-align: inherit; text-decoration: none; z-index: 0;">.</a></div>
</div>Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com0tag:blogger.com,1999:blog-4996769537501094384.post-40644727786259997102014-10-13T10:44:00.000+02:002017-07-05T12:40:57.703+02:00¿Cómo se formó el Mediterráneo? ¿Cuándo?<div style="margin: 0px;">
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<span style="font-size: x-small; text-align: justify;">[E</span><span style="font-size: x-small; text-align: justify;">ste post está orientado a estudiantes que comienzan una carrera universitaria en ciencias, no necesariamente geología]</span></div>
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El Mar Mediterráneo <span style="text-align: -webkit-auto;">es lo que resta en la actualidad </span><span style="text-align: -webkit-auto;">del antiguo </span><a href="http://en.wikipedia.org/wiki/Tethys_Ocean" style="text-align: -webkit-auto;">Océano de Tethys</a>, que quedó atrapado entre las placas tectónicas de África y <a href="https://es.wikipedia.org/wiki/Placa_euroasi%C3%A1tica">Eurasia</a> durante su lenta aproximación en <span class="Apple-style-span" style="text-align: -webkit-auto;">los últimos <a href="http://es.wikipedia.org/wiki/Era_Cenozoica">65 millones de años</a></span>. A causa de esta aproximación,<span style="text-align: -webkit-auto;"> </span>la <a href="https://es.wikipedia.org/wiki/Corteza_oce%C3%A1nica">corteza terrestre oceánica</a> que alojaba al Océano de Tethys fue obligada a hundirse (a <i>subducir</i>) en el manto terrestre<i>,</i> bajo Eurasia, tras lo cual se produjo <span style="text-align: -webkit-auto;">la</span> colisión entre ambos continentes, formando los Pirineos, los Alpes y las Montañas de Zagros (<a href="https://es.wikipedia.org/wiki/Orogenia_Alpina"><i>orogenia Alpina</i></a>). Fue así como quedaron desconectados el actual Mar Mediterráneo y el Océano Índico hace unos 15 millones de años.<br />
<span style="text-align: -webkit-auto;">Sólo en el Mediterráneo Oriental quedan restos de aquella corteza de Tethys que aún no han subducido y que de hecho constituyen la corteza oceánica más antigua preservada en el planeta: unos 270 millones de años de edad. Puedes descargar este espectacular <a href="https://drive.google.com/file/d/0B_xuyENh5ksFeFBXYlpFQmNKNDA/edit?usp=sharing">KML para Google Earth</a> y visualizar la edad de formación de la corteza terrestre. </span><br />
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<iframe allowfullscreen='allowfullscreen' webkitallowfullscreen='webkitallowfullscreen' mozallowfullscreen='mozallowfullscreen' width='320' height='266' src='https://www.youtube.com/embed/ft-dP2D7QM4?feature=player_embedded' frameborder='0'></iframe></div>
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<tr><td class="tr-caption" style="font-size: 12.7272720336914px;">Fig. 1. Movimiento de las placas tectónicas deducido principalmente a partir del campo magnético grabado en las rocas (técnica conocida como <a href="https://es.wikipedia.org/wiki/Paleomagnetismo">paleomagnetismo</a>) y de la geología y paleontología observadas en superficie. </td></tr>
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-m5byU3-3GXg/WVzB-HxBsqI/AAAAAAAA2IM/onZaA1r5c0MkmC8NuxuPCddzNSC4ee9BgCLcBGAs/s1600/TristanFig6_500.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="351" data-original-width="500" height="224" src="https://1.bp.blogspot.com/-m5byU3-3GXg/WVzB-HxBsqI/AAAAAAAA2IM/onZaA1r5c0MkmC8NuxuPCddzNSC4ee9BgCLcBGAs/s320/TristanFig6_500.gif" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Fig. 2. Movimiento de rotación de África respecto a Eurasia en los últimos 190 Millones de años. A partir de medidas de paleomagnetismo en rocas. Vía MantlePlumes.org</td></tr>
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<span style="text-align: -webkit-auto;">Es sorprendente encontrar la corteza oceánica más antigua del planeta en el Mediterráneo, pues e</span>l acercamiento entre Europa y África continúa hoy a un ritmo geológicamente rápido, de unos 4 milímetros por año en la región más occidental (entre España y Marruecos), y <span style="text-align: -webkit-auto;">a velocidades aún mayores y con mayor actividad sísmica en Grecia o Turquía. </span><br />
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<a href="http://1.bp.blogspot.com/-qGPVf9AaOV0/VCwLCgvgZHI/AAAAAAAAdVo/UOG8y7av2-A/s1600/Fig2_KinematicModeling.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="146" src="https://1.bp.blogspot.com/-qGPVf9AaOV0/VCwLCgvgZHI/AAAAAAAAdVo/UOG8y7av2-A/s1600/Fig2_KinematicModeling.jpg" width="200" /></a></div>
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Fig. 3. Movimiento relativo de<br />
<span style="font-size: 12.7272720336914px;">Anatolia </span><span style="font-size: 12.7272720336914px;">y el este del </span><span style="font-size: 12.7272720336914px;">Mediterráneo </span><br />
<span style="font-size: 12.7272720336914px;">respecto a </span><span style="font-size: 12.7272720336914px;">Eurasia, </span><span style="font-size: 12.7272720336914px;">o</span><span style="font-size: 12.7272720336914px;">btenido </span><span style="font-size: 12.7272720336914px;">a </span><br />
<span style="font-size: 12.7272720336914px;">partir </span><span style="font-size: 12.7272720336914px;">de </span><span style="font-size: 12.7272720336914px;">medidas </span><span style="font-size: 12.7272720336914px;">de GPS de alta </span><br />
<span style="font-size: 12.7272720336914px;">precisión. </span><span style="font-size: 12.7272720336914px;">La longitud de </span><span style="font-size: 12.7272720336914px;">las </span><span style="font-size: 12.7272720336914px;">flechas </span><br />
<span style="font-size: 12.7272720336914px;">indica </span><span style="font-size: 12.7272720336914px;">la </span><span style="font-size: 12.7272720336914px;">velocidad</span><span style="font-size: 12.7272720336914px;"> </span><span style="font-size: 12.7272720336914px;">actual </span><span style="font-size: 12.7272720336914px;">debido a </span><br />
<span style="font-size: 12.7272720336914px;">la tectónica </span><span style="font-size: 12.7272720336914px;">medida en una </span><span style="font-size: 12.7272720336914px;">estación </span><br />
<span style="font-size: 12.7272720336914px;">de GPS</span><span style="font-size: 12.7272720336914px;">. </span><span style="font-size: 12.7272720336914px;">Las mayores </span><span style="font-size: 12.7272720336914px;">corresponden </span><br />
<span style="font-size: 12.7272720336914px;">a </span><span style="font-size: 12.7272720336914px;">4 </span><span style="font-size: 12.7272720336914px;">cm/año.</span></div>
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-0byaKURhphY/VDz-QTbLhtI/AAAAAAAAdgI/1QoF1Dhb8Vw/s1600/Jime%CC%81nez-Munt%2Bet%2Bal.%2C%2B2003%2B-%2BMediterranean%2Bvelocity%2Bstrain%2Brate%2Bmodel.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="245" src="https://1.bp.blogspot.com/-0byaKURhphY/VDz-QTbLhtI/AAAAAAAAdgI/1QoF1Dhb8Vw/s1600/Jime%CC%81nez-Munt%2Bet%2Bal.%2C%2B2003%2B-%2BMediterranean%2Bvelocity%2Bstrain%2Brate%2Bmodel.jpg" width="400" /></a></td></tr>
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Fig. 4. Modelo de la velocidad tectónica en el Mediterráneo <span style="font-size: 12.7272720336914px;">(flechas </span></div>
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<span style="font-size: 12.7272720336914px;">relativas a Eurasia</span><span style="font-size: 12.7272720336914px;">) y de las </span><span style="font-size: 12.7272720336914px;">tasas de deformación que implican</span><span style="font-size: 12.7272720336914px;">. </span></div>
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<span style="font-size: 12.7272720336914px;">De </span><a href="http://www.ija.csic.es/gt/ivone/publications.html" style="font-size: 12.7272720336914px;">Jiménez-Munt y coautores, 2003, JGR</a><span style="font-size: 12.7272720336914px;">.</span></div>
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<span style="text-align: justify;">Pero el Mar Mediterráneo ha tenido una evolución tectónica más compleja que la simple subducción de África bajo Eurasia, como reflejan la heterogénea distribución de los terremotos (Fig. 5) y los varios dominios o subplacas cuyos movimientos tectónicos responden de manera poco intuitiva al acercamiento entre los dos continentes (Fig. 6b).</span></div>
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<tr><td style="text-align: center;"><a href="http://i481.photobucket.com/albums/rr177/chrispy_post/depth.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="507" src="https://i481.photobucket.com/albums/rr177/chrispy_post/depth.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Fig. 5. Distribución de terremotos y su profundidad en el área mediterránea.</td></tr>
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Como consecuencia de la geometría heredada de ambos continentes, se han formado varias zonas de subducción diferenciadas (Fig. 6b) en las que la corteza oceánica de Tethys es <i>cabalgada</i> por los márgenes del sur de Europa antes de sumergirse en el <a href="http://es.wikipedia.org/wiki/Manto_terrestre">manto terrestre</a>. Un ejemplo es la subducción que se produce en el Arco de Calabria (Sicilia y sur de Italia), donde la<span style="text-align: -webkit-auto;"> placa Africana</span><span class="Apple-style-span" style="text-align: -webkit-auto;"> subduce bajo el Mar Tirreno, dando origen a una importante actividad sísmica y volcánica (Etna, Stromboli, etc, Fig. 6c). </span></div>
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-O-X3OkQySfg/VCwP0bBqTHI/AAAAAAAAdWA/rhUdd1oKypI/s1600/Plate%2BTectonics%2Bcartoon.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="176" src="https://1.bp.blogspot.com/-O-X3OkQySfg/VCwP0bBqTHI/AAAAAAAAdWA/rhUdd1oKypI/s1600/Plate%2BTectonics%2Bcartoon.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Fig. 6a. Esquema del proceso de subducción<br />
de las placas tectónicas oceánicas.</td></tr>
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<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-rQ7hvwqxlNM/VDOmJRZlfHI/AAAAAAAAdaE/FIdDyqo4TcE/s1600/Faccenna%2Bet%2Bal.%2C%2B2001%2C%2BGJI%2B-%2Bslab%2Bretreat.png" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto; text-align: center;"><img border="0" height="320" src="https://3.bp.blogspot.com/-rQ7hvwqxlNM/VDOmJRZlfHI/AAAAAAAAdaE/FIdDyqo4TcE/s1600/Faccenna%2Bet%2Bal.%2C%2B2001%2C%2BGJI%2B-%2Bslab%2Bretreat.png" width="196" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Fig. 6c. Hundimiento y retroceso del <i>slab</i><br />
(de la porción de placa tectónica subducida)<br />
de Tethys dando lugar a la formación por<br />
extensión de la corteza del Mar Mediterráneo<br />
(Mar Tirreno en la imagen). África <span style="font-size: 12.7272720336914px;">a la </span><br />
<span style="font-size: 12.7272720336914px;">derecha; Europa a la Izda. </span><span style="font-size: xx-small;">De Faccenna </span><br />
<span style="font-size: xx-small;">et al., GJI, 2001)</span></td></tr>
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<tr><td><a href="http://jgs.lyellcollection.org/content/164/2/297/F3.large.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="212" src="https://jgs.lyellcollection.org/content/164/2/297/F3.large.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.7272720336914px;">Fig. 6b. Mapa tectónico simplificado del Mediterráneo <span style="font-size: 12.7272720336914px;">actual</span><span style="font-size: 12.7272720336914px;">, </span><br />
<span style="font-size: 12.7272720336914px;">mostrando la edad de formación de la nueva corteza oceánica</span><br />
<span style="font-size: 12.7272720336914px;"> (azul, </span>de hasta 25 millones de años<span style="font-size: 12.7272720336914px;">) tras la subducción del </span><br />
<span style="font-size: 12.7272720336914px;">Tethys en la parte occidental</span><span style="font-size: 12.7272720336914px;">. Las zonas mucho más antiguas </span><br />
<span style="font-size: 12.7272720336914px;">de corteza oceánica en la zona oriental (morado) </span><br />
<span style="font-size: 12.7272720336914px;">corresponden </span><span style="font-size: 12.7272720336914px;">a la placa del antiguo océano de Tethys. Las </span><br />
<span style="font-size: 12.7272720336914px;">líneas </span><span style="font-size: 12.7272720336914px;">dentadas rojas indican </span><span style="font-size: 12.7272720336914px;">las </span><span style="font-size: 12.7272720336914px;">fosas donde esa placa se </span><br />
<span style="font-size: 12.7272720336914px;">adentra en el manto (subduce) bajo </span><span style="font-size: 12.7272720336914px;">Europa.</span><br />
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<span class="Apple-style-span" style="text-align: -webkit-auto;">Para entender la formación del Mediterráneo es clave comprender un proceso llamado <i><b>extensión de tras-arco</b></i> (<i><a href="http://en.wikipedia.org/wiki/Back-arc_basin">back-arc</a> extension</i>), que es el estiramiento o extensión de la corteza terrestre que ocurre <i>detrás</i> de una zona de subducción, encima del <i>slab subducido</i> (a la izda. en el corte de la Fig. 6c). Debido a la mayor densidad de la placa de Tethys, ésta se hundió en el manto succionando y estirando la placa bajo la cual subducía (Europa). </span><span style="text-align: start;">A consecuencia de esa dinámica (Fig. 7) se separaron del continente europeo las islas de Córcega, Cerdeña y Baleares.</span><span style="text-align: start;"> </span><span style="text-align: -webkit-auto;">Otro ejemplo más lejano del mismo proceso es la separación que actualmente se produce entre Japón y Asia, debida a la subducción de la placa Pacífica bajo la fosa donde se originó el </span><a href="http://retosterricolas.blogspot.com/search/label/Tohoku-Oki" style="text-align: -webkit-auto;">terremoto de Sendai</a><span style="text-align: -webkit-auto;">. </span><br />
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<a href="http://4.bp.blogspot.com/-YJsbWNL3_Vw/VC3TimGkOSI/AAAAAAAAdWw/sNkeCKTI_v0/s1600/SubZone.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em; text-align: right;"><img border="0" height="122" src="https://4.bp.blogspot.com/-YJsbWNL3_Vw/VC3TimGkOSI/AAAAAAAAdWw/sNkeCKTI_v0/s1600/SubZone.jpg" width="200" /> <iframe allowfullscreen='allowfullscreen' webkitallowfullscreen='webkitallowfullscreen' mozallowfullscreen='mozallowfullscreen' width='320' height='266' src='https://www.youtube.com/embed/cVulRP2tUGM?feature=player_embedded' frameborder='0'></iframe></a></div>
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<span style="font-size: x-small;">Fig. 7. Izda.: la extensión de tras-arco es un estiramiento de la corteza que se produce encima de los slabs subducidos. Vídeo: Simulación de la extensión de tras-arco (<i><a href="https://en.wikipedia.org/wiki/Back-arc_basin">back-arc extension</a></i>) debida al hundimiento y la retirada de una placa tectónica (<i>slab retreat </i>or<i> <a href="http://www4.ncsu.edu/~jdbowman/index_files/documents/DelaminationSlabBreakoffandSlabRollback_000.pdf">slab rollback</a></i>), modelo de <a href="http://www.nature.com/nature/journal/v508/n7495/full/nature13033.html">Moresi y coautores</a>. </span><span style="font-size: x-small;">Si el lado izquierdo fuera África y el derecho Europa (al revés en el esquema de la izda.), entonces la extensión que se produce en el centro correspondería al Mediterráneo. </span></div>
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<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-OAFxy8JQTUM/WVzBwuAD0WI/AAAAAAAA2II/jUkQ6ipi9EEenzxMyF8BJjuEect29GafQCLcBGAs/s1600/image9RS.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="320" data-original-width="474" height="216" src="https://2.bp.blogspot.com/-OAFxy8JQTUM/WVzBwuAD0WI/AAAAAAAA2II/jUkQ6ipi9EEenzxMyF8BJjuEect29GafQCLcBGAs/s320/image9RS.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Fig. 8. Reconstrucción de la retirada del slab (<i>slab retreat</i>) que da lugar a la extensión del Mar Tirreno y del Golfo de Valencia, separando las islas Baleares de la Península Ibérica, hace unos 25 millones de años. Las líneas discontinuas indican la posición de la subducción hace 30 y 16 millones de años. Las flechas negras indican también el mismo proceso ocurrido en el arco helénico (Grecia) y en la Cuenca Panónica (Hungría/Rumanía).</td></tr>
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En resumen: hoy el Mediterráneo occidental ocupa una enorme cuenca extensiva de tras-arco desgarrada tras la subducción de la corteza oceánica de Tethys bajo el continente europeo y la posterior colisión continental entre África y Eurasia. Esta es al menos la visión más generalizada hoy entre los geólogos.<br />
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<span style="text-align: justify;">La </span><a href="http://naukas.com/2012/01/24/mediterraneo/" style="text-align: justify;">conexión del Mediterráneo con el océano global</a><span style="text-align: justify;"> fue cancelada también por el lado Atlántico, </span>durante la <a href="http://es.wikipedia.org/wiki/Crisis_salina_del_Mesiniense">crisis salina del Messiniense</a>, pero esto supuso sólo un breve episodio de 630,000 años, hace unos 6 millones de años. El <a href="http://retosterricolas.blogspot.com/2009/12/inundacion-catastrofica-de-un.html">restablecimiento de las condiciones </a><i><a href="http://retosterricolas.blogspot.com/2009/12/inundacion-catastrofica-de-un.html">normales</a> </i>al final de ese episodio simplemente restituyó la conexión atlántica y la configuración del Mediterráneo que ya era muy parecida a la actual antes de la crisis salina. </div>
Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com3Mediterranean Sea34.928930875138278 15.39966100000003710.745175875138276 -25.908932999999962 59.112685875138283 56.708255000000037tag:blogger.com,1999:blog-4996769537501094384.post-29326389813083828532014-08-18T18:03:00.001+02:002014-12-01T14:43:45.452+01:0067P - how much is a comet worth<div class="" style="clear: both;">
I've been trying to learn a bit more about comets (call it <i>summer-research</i>) taking the chance of the visit of the ESA <a href="http://www.esa.int/Our_Activities/Space_Science/Rosetta">Rosetta mission</a> to comet 67P (aka Churyumov–Gerasimenko).<br />
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Comets are small bodies of rock and ice thought to form in the outer regions of the solar system at the same time planets were formed, ca. 4.6 billion years ago. An important <i>known unknown</i> about comets is their relative contribution to the accumulation of water in the early Earth. So learning about them is learning about our planet too.<br />
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67P is a 4 km-long ice body orbiting around the sun every 6 years, following an elliptical orbit ranging between those of the Earth and Jupiter.</div>
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-M5Mb-UWx4eU/U--uG-FkR5I/AAAAAAAAcq8/pLY7zKU8yHo/s1600/Barcelona%2C%2B67P%2Bcomet%2C%2Bat%2Bnight%2B-%2Bsmall.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://1.bp.blogspot.com/-M5Mb-UWx4eU/U--uG-FkR5I/AAAAAAAAcq8/pLY7zKU8yHo/s1600/Barcelona%2C%2B67P%2Bcomet%2C%2Bat%2Bnight%2B-%2Bsmall.jpg" height="552" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Barcelona and 67P, to scale</td></tr>
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The shape of 67P suggests that it might be the result of the accretion of smaller comets. In fact, one thing that surprises many of us who are unfamiliar with comets is their low density. Most of the comet you see in these pictures has been left empty during its formation. 67P is about <strike>10</strike> 2.5 times lighter than water: <strike>102 </strike>400 kg/m3 (figures updated after Rosetta's approach), implying that it is a very porous body. Is this related to an accretion process?<br />
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<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-msC5tkX51dU/U-56BocjwCI/AAAAAAAAcqo/bLGzErlduNE/s1600/Comet_on_12_August_2014_-_NavCam_node_full_image_2.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://4.bp.blogspot.com/-msC5tkX51dU/U-56BocjwCI/AAAAAAAAcqo/bLGzErlduNE/s1600/Comet_on_12_August_2014_-_NavCam_node_full_image_2.jpg" height="320" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: white; color: #031e31; font-family: verdana, arial; font-size: 12px; text-align: left;">Image taken on 2014-08-12 from a distance of 103 km. Credit: </span><span style="background-color: white; color: #031e31; font-family: verdana, arial; font-size: 12px; text-align: left;">ESA/Rosetta/NAVCAM</span></td></tr>
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Another curious fact: 67P used to have a <a href="https://en.wikipedia.org/wiki/Perihelion">perihelion</a> distance of 2.7 AU (1 AU = distance from the Sun to the Earth), but in February 1959 an approach to Jupiter reduced this to only 1.3 AU, where it remains today. Comets are often shifted by the gravity field of planets, but recent events like this remind us that we are not in a static Solar System. The same process can lead to the split of comets in pieces: a beautiful example is given by the comets 42P/Neujmin and 53P/Van Biesbroeck, which appear to be fragments of a parent comet. This is based on computer integration, a reconstruction of their past position, showing that both comets were close to Jupiter in January 1850 and had nearly identical orbits before that. The debris produced by such comet disintegrations is often responsible for meteor showers like the Perseids seen worldwide in middle August.<br />
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-Vv4Z4eiJsW0/U-5x0RrDubI/AAAAAAAAcqQ/VQhysCHQcs4/s1600/NavCam_animation_6_August_medium.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="http://1.bp.blogspot.com/-Vv4Z4eiJsW0/U-5x0RrDubI/AAAAAAAAcqQ/VQhysCHQcs4/s1600/NavCam_animation_6_August_medium.gif" height="200" width="200" /></a></td></tr>
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<tr><td class="tr-caption" style="font-size: 13px;"><span style="background-color: white; color: #031e31; font-family: verdana, arial; font-size: 12px; text-align: left;">Approach to a distance of 104 km. <br />67P rotates once every 12.7 hours. <br />Credit: </span><span style="background-color: white; color: #031e31; font-family: verdana, arial; font-size: 12px; text-align: left;">ESA/Rosetta/NAVCAM</span></td></tr>
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</td></tr>
</tbody></table>
<div>
<br /></div>
<div>
Rosetta's won't be the first mission actually touching down on a comet (check this <a href="https://en.wikipedia.org/wiki/List_of_comets_visited_by_spacecraft">list of space missions that have approached comets</a>, and see the unsubtle 'landing' of <i>Deep Impact</i> in the animation below). But it is the first mission ever to smoothly land on a comet (<i>Philae</i> lander) and to analyze its surface. And it is the first mission to orbit a comet, something remarkable since the escape velocity of 67P is only 0.5 m/s. It will also be the first mission to land a probe on the surface and, in the words of ESA, Rosetta will be "the first spacecraft to fly alongside a comet as it heads towards the inner Solar System, watching how a frozen comet is transformed by the warmth of the Sun". A lander will sample the composition and structure of the comet nucleus, drilling more than 20 cm into the subsurface for analysis at the onboard laboratory. </div>
<div>
<br /></div>
<div>
Rosetta has costed the europeans around 1 billion euros (10^9 €) through a consortium of the German Aerospace Research Institute (DLR) with ESA, CNES, and european and american research institutes. The results will provide information on how comets form and also on the early stages of the Solar System. It should contribute to the discussion on where did the terrestrial water form and when did it arrive here. Previous studies have shown that the isotope ratios of hydrogen in other comets is different from that of oceanic water, but it remains unclear that these comets were representative enough of the comet orbits most likely to contribute to our waters. New answers will arrive soon, together with new questions. </div>
</div>
<div>
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-NQcHWw3RKeQ/U-54d1o4f9I/AAAAAAAAcqc/YMAAee6PyEg/s1600/ITS_Impact.gif" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="http://3.bp.blogspot.com/-NQcHWw3RKeQ/U-54d1o4f9I/AAAAAAAAcqc/YMAAee6PyEg/s1600/ITS_Impact.gif" height="200" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Deep Impact</i> colliding with comet Temple 1 in 2005</td></tr>
</tbody></table>
</div>
Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com0Barcelona, Spain41.3850639 2.173403499999949441.1944764 1.8506799999999495 41.5756514 2.4961269999999494tag:blogger.com,1999:blog-4996769537501094384.post-22548547736126805762014-06-05T12:56:00.001+02:002017-03-07T14:09:40.321+01:00Dynamic topography vs. isostasy: The importance of definitions<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://upload.wikimedia.org/wikipedia/commons/f/fa/Airy_Isostasy.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://upload.wikimedia.org/wikipedia/commons/f/fa/Airy_Isostasy.jpg" width="294" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Fig. 1. Airy isostatic model: every column of rock above the <br />
compensation level should have the same weight. <br />
High topography is compensated by a mass deficit at <br />
the base of the crust (crustal root) </td></tr>
</tbody></table>
The term 'Dynamic Topography' is one of the top trending topics in Solid Earth science. It has now prevailed for more than 2 decades, but still the concept involves significant confusion. Dynamic Topography refers to a part of the elevation of the Earth surface that cannot be accounted by the classical crustal isostatic models (Pratt or Airy). But is the term referring to all mantle-sourced loads? Or only to those forces created by the dynamic flow of the mantle? Let's see first where the current confusion exactly comes from.<br />
<br />
The term was actually <b>coined by oceanographers</b> to refer to the deviations of the surface of the ocean relative to the Geoid (eg., Bruce, 1968; Wyrtki, 1975). In principle, the geoid should perfectly fit the surface of the ocean, since it is an equipotential surface of the gravity field, but the flow of water adds a secondary shift of the surface, normally less than a meter. This deviation from the surface predicted for a 'static' ocean (ie., the geoid) can be detected in satellite altimetry data because the signal noise introduced by tides, waves, and wind can be removed by time-filtering. The remaining deviation from the geoid is referred to by oceanographers as 'dynamic topography' and is known to be related to the water currents in the ocean.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-qQ7JzFwUAkA/U3DelSjq4UI/AAAAAAAAbCc/VnskLXfnUa0/s1600/dynamic+ocean+topography+NASA+-+DOT_gaussave_111km_moll.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="257" src="https://2.bp.blogspot.com/-qQ7JzFwUAkA/U3DelSjq4UI/AAAAAAAAbCc/VnskLXfnUa0/s1600/dynamic+ocean+topography+NASA+-+DOT_gaussave_111km_moll.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div style="background-color: white; font-family: Arial, Helvetica, Verdana, sans-serif; font-size: 12px; text-align: center;">
<span style="font-family: "times"; font-size: 12.727272033691406px;">Fig. 2.</span><span style="font-family: "times"; font-size: 12.727272033691406px;"> </span>Mean <b>ocean dynamic topography</b> from http://grace.jpl.nasa.gov, updated from <span style="font-size: 12px;">Tapley et al., 2003).</span></div>
<div style="background-color: white; font-family: Arial, Helvetica, Verdana, sans-serif; font-size: 12px; text-align: center;">
<span style="font-size: 12px; text-align: start;"> It </span><span style="font-size: 12px; text-align: start;">measures the long-term-averaged strength of ocean currents, the 'steady-state'</span><br />
<span style="font-size: 12px; text-align: start;">circulation. </span></div>
</td></tr>
</tbody></table>
In the 80s the term was adopted by solid-earth scientists (Hager et al., 1985, <i>Nature</i>). The authors did not follow the original oceanographic meaning, but instead they included 'static' forces originated within the lithosphere (such as the weight of sinking plates, or <i>slab pull</i>) as well as forces caused by flow in the mantle.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td><a href="http://2.bp.blogspot.com/-4A5wK-QyAok/U3DwXXfZRSI/AAAAAAAAbCs/mxgigDjWBjo/s1600/Liu+et+al.,+2008+-+Science+-+mantle+flow+and+dynamic+topography+-+crop.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://2.bp.blogspot.com/-4A5wK-QyAok/U3DwXXfZRSI/AAAAAAAAbCs/mxgigDjWBjo/s1600/Liu+et+al.,+2008+-+Science+-+mantle+flow+and+dynamic+topography+-+crop.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.727272033691406px;">Mantle convection model: Mantle temperature (color shading) and flow (arrows). Lines indicate the calculated dynamic topography (blue line) and the horizontal component of plate motion (red, positive means eastward). From Liu et al., 2008, <i>Science</i></td></tr>
</tbody></table>
This made sense at the time because there was a big questionmark (still poorly answered today) about the origin of <i><b>hidden loads</b></i>, the enigmatic forces needed to explain the depth of sediment accumulations next to mountain belts (see <a href="http://books.google.es/books?id=syHBTAMSEuYC&source=gbs_navlinks_s">Allen's book</a> <i>Foreland basins</i>, or <a href="https://docs.google.com/uc?id=0B_xuyENh5ksFMzI3OGE0NDctNWExOC00YmVlLWI5MjAtY2ZiMzk5MjZjN2Vi&export=download&hl=en">this article pdf</a>). Sedimentary basins next to orogens in compressional plate boundaries are formed by the isostatic sinking (subsidence) of the lithosphere due to the weight of the growing orogen. These settings became very attractive in solid-earth science not only for prospection purposes, but also because they provide an opportunity to understand how tectonic processes interact with the erosion and transport of sediment in the surface, since the sedimentary layers in such foreland basins record the tectonic evolution of the mountain belt. After many of these foreland basins were modeled, it became clear that the isostatic load of the orogen was generally insufficient to explain the amount of subsidence of the basin. But linking all the hidden load to dynamic effects is misleading, because of the presence of static forces such as the weight of a sinking plate attached to the surface (a lithospheric slab), well known since plate tectonics became mainstream. Another key to understanding the confusion is that before the widespread development of <b>seismic tomography</b>, everything occurring below crustal levels was far more conjectural than today. As a result, part of the Solid-Earth community used the term <i>dynamic topography</i> to refer to all deep-seated forces (originated below the crust) that had an effect on topography, including for instance changes in the thickness of the lithospheric mantle, or a lithospheric slab.<br />
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-j0QjFoznOpQ/U5BFir-8g7I/AAAAAAAAbWI/SdDyrSSVlyo/s1600/static+load.gif" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://4.bp.blogspot.com/-j0QjFoznOpQ/U5BFir-8g7I/AAAAAAAAbWI/SdDyrSSVlyo/s1600/static+load.gif" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: white;">Fig. 3.</span><span style="background-color: white;"> </span>Two static forces in balance<br />
(weight of the books and the<br />
counteracting human force)</td></tr>
</tbody></table>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-4LDn1yVUTVc/U5BFiiJP8DI/AAAAAAAAbWE/xN0_pAi30q8/s1600/static+dynamic+load.gif" imageanchor="1" style="clear: right; display: inline !important; margin-bottom: 1em; margin-left: auto; margin-right: auto; text-align: center;"><img border="0" src="https://2.bp.blogspot.com/-4LDn1yVUTVc/U5BFiiJP8DI/AAAAAAAAbWE/xN0_pAi30q8/s1600/static+dynamic+load.gif" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Dynamic forces are added to the <br />
static force to recover the balance<br />
and avoid the books from falling.</td></tr>
</tbody></table>
In physics, static vs. dynamic forces refer to whether the forces are in equilibrium (perfectly compensated) or not, and dynamic physical problems refer to motions involving acceleration. This is an additional source of confusion, since both the ocean flow and the Earth's mantle flow can be under steady-state flow and still inflict a constant deflection of the topographic surface, that we yet call 'dynamic'.<br />
<br />
But sticking to the original oceanographic definition (as for example in <a href="http://www.nature.com/ngeo/journal/v3/n12/abs/ngeo1020.html">Braun 2010</a>), the dynamic topography of the solid-earth should restrict to the change in elevation produced by dynamic forces related to mantle viscous flow (and flow can only occur beneath the boundary layer of the mantle, underneath the lithosphere). This definition seems robust because the lithosphere is defined based on its strength relative to the underlying asthenosphere, and hence flow-related stresses are expected to be negligible above the lithosphere-asthenosphere boundary (LAB). The fact that the flow is generated by density contrasts does not mean that the forces can be mistaken for static ones, because those density anomalies are out of the rigid body being deformed (the lithosphere).<br />
<br />
We therefore can split the observed topography OT into:<br />
OT = CIT + LMIT + MFDT<br />
where CIT is the crustal isostatic topography; LMIT is the Lithospheric-mantle isostatic topography (including slabs attached to the Earth's crust, or the thinning of the lithosphere); and MFDT is the sublithospheric mantle-flow dynamic topography. Note that OT-CIT (easy to calculate using global databases of crustal thickness) is often called residual topography (RT).<br />
<br />
Following this notation, the confusion can be described as emanating from some authors referring to LMIT+MFDT (which equals RT) as the dynamic topography, instead of MFDT alone. While this RT ranges in the order of +-1 km, there seems to be no consensus yet as to how large can MFDT be, with values ranging between that same value and a few hundred meters.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-uDB05Hh9lzc/WL6w0paqZcI/AAAAAAAAzJs/yFouqj5vWhIHYA-0Qf1eumfn2EnP8_xngCLcB/s1600/Screen%2BShot%2B2017-03-07%2Bat%2B14.07.49.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="398" src="https://2.bp.blogspot.com/-uDB05Hh9lzc/WL6w0paqZcI/AAAAAAAAzJs/yFouqj5vWhIHYA-0Qf1eumfn2EnP8_xngCLcB/s640/Screen%2BShot%2B2017-03-07%2Bat%2B14.07.49.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div style="font-size: 12.8px;">
<span style="background-color: white;">Fig. 4.</span><span style="background-color: white;"> </span>Global free-air gravity anomaly from GRACE. The low values (+-40 mGal) in comparison with the +- 300 mGal that are often attained in smaller regional scales shows that the crust is in overall isostatic equilibrium: the mass excess of topography at high-elevation areas is compensated by a mass deficit at the base of the crust. For this reason there is little correlation between anomaly and continents. The Hawaiian, Yellowstone, Iceland hotspots are represented by highs. Subduction zones show an asymmetrical pair of low & high anomaly. The Hudson Bay undergoes a glacial rebound in response to the deglaciation (+ info <a href="http://principles.ou.edu/grav_ex/filter/filter.htm">here</a>).</div>
</td></tr>
</tbody></table>
<br />
Support for the smaller MFDT values comes from reasonings like this: Consider a Stokes sphere sinking or rising in a viscous fluid by virtue of its density contrast with the surrounding fluid (the viscous mantle for us). The vertical velocity of this sphere can be analytically solved and the expression obtained for the dynamic topography it produces depends on its radius <i>a</i>, its density contrast relative to the fluid, the depth of the sphere, and the distance <i>R</i> from the measuring point in the surface to the center of the sphere.<br />
<div style="text-align: center;">
MFDT = ∆h[m] = 2*∆density * a^3 * D * (3D^2+3a^2-5*D^2*a^2/R^2) / (3*fluid_density*R^5) </div>
<div style="text-align: center;">
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td><a href="http://3.bp.blogspot.com/--QzUUHBfNX8/U57yAP8RarI/AAAAAAAAbak/GfwYuCHLmvU/s1600/Screen+Shot+2014-06-16+at+15.31.19.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="146" src="https://3.bp.blogspot.com/--QzUUHBfNX8/U57yAP8RarI/AAAAAAAAbak/GfwYuCHLmvU/s1600/Screen+Shot+2014-06-16+at+15.31.19.png" width="320" /></a></td></tr>
<tr><td class="tr-caption">Stokes' sphere sinking in a viscous fluid. The gravity anomaly and dynamic topography it generates are linearly proportional to each other.</td></tr>
</tbody></table>
</div>
<div style="text-align: left;">
Because the free-air gravity anomaly produced by the same sphere (<span style="text-align: center;">∆g) </span>follows a similar equation, the relation between gravity and MFDT conveniently depends only on the of fluid density, to a first approach:</div>
<div style="text-align: center;">
∆g[mGal] = 2πG * density[kg m<span style="font-size: xx-small;">-3</span>] * MFDT[m]</div>
<br />
This means that the +-40 mGal anomalies shown in the global map above should correspond to a dynamic topography smaller that 300-400 m (see P. Molnar's talk linked below).<br />
<br />
Clearly, if we knew well the two isostatic contributions CIT+LMIT, then we would be able to attribute the rest to the flow in the mantle and learn about what happens at those depths. As Jean Braun puts it: "Mantle dynamics remain poorly constrained, but by linking mantle flow to surface topography (...) we can use the geological record to constrain the dynamics and viscosity of the mantle and the density structure that controls its flow".<br />
The problem is that there are too many unknowns in the equation: computer models of 3D mantle flow that estimate dynamic topography rely on seismic tomographic imaging of the mantle that provide the distribution of seismic velocity anomaly but how to <i>translate</i> this wave velocity into lateral inhomogeneities in density and viscosity is poorly known. So, fitting the computer models to the weak available observations of dynamic topography and plate tectonic reconstructions will provide only hints on a vague combination of the velocity-viscosity and the velocity-density relationships. So, this will remain as an <i>Earthling Challenge</i> (a <i>Reto Terrícola</i>) for quite some time.<br />
<br />
For more information, I recommend <a href="https://www.youtube.com/watch?v=b26l7MTIDFo">Peter Molnar's talk</a> on youtube, <a href="http://earth-literally.blogspot.com.es/2011/09/dynamic-topography-whats-in-name.html">Philip Allen's blog post</a>, or Braun's paper listed below. PS: Check also this recent <a href="https://www.youtube.com/watch?v=AuuW-PzQhlc">talk by Jean Braun</a> on the interaction between erosion and dynamic topography.<br />
<br />
<br />
References<br />
<ul>
<li><span style="font-size: x-small;"><span style="background-color: white; color: #222222; font-family: "arial" , sans-serif; line-height: 16.1200008392334px;">Allen, 2010, </span>Surface impact of mantle processes, <i>Nature Geoscience</i>.</span></li>
<li><span style="font-size: x-small;"><span style="background-color: white; color: #222222; font-family: "arial" , sans-serif; line-height: 16.1200008392334px;">Braun, Jean. "The many surface expressio</span><span style="background-color: white; color: #222222; font-family: "arial" , sans-serif; line-height: 16.1200008392334px;">ns of mantle dynamics." </span><i style="background-color: white; color: #222222; font-family: Arial, sans-serif; line-height: 16.1200008392334px;">Nature Geoscience</i><span style="background-color: white; color: #222222; font-family: "arial" , sans-serif; line-height: 16.1200008392334px;"> 3.12 (2010): 825-833.</span></span></li>
<li><span style="font-size: x-small;">Bruce, J. G. "Comparison of near surface dynamic topography during the two monsoons in the western Indian Ocean." Deep Sea Research and Oceanographic Abstracts. Vol. 15. No. 6. Elsevier, 1968.</span></li>
<li><span style="font-size: x-small;">Faccenna, C., Becker, T. W., Auer, L., Billi, A., Boschi, L., Brun, J.-P., Capitanio, F. A., Funiciello, F., Horvath, F., Jolivet, L., Piromallo, C., Royden, L., Rossetti, F., and Serpelloni, E.: Mantle dynamics in the Mediterranean. In press at Rev. Geophys., 2014. <a href="http://geodynamics.usc.edu/~becker/preprints/fbabbbcfhjprrs14.pdf">PDF</a></span></li>
<li><span style="font-size: x-small;">Hager, Bradford H., et al. "Lower mantle heterogeneity, dynamic topography and the geoid." Nature 313.6003 (1985): 541-545.</span></li>
<li><span style="font-size: x-small;">Tapley B.D., D.P. Chambers, S. Bettadpur and J.C. Ries, 2003: Large scale ocean circulation from the GRACE GGM01 Geoid. Geophys. Res. Letters 30 (22):doi:10.1029/2003GL018622</span></li>
<li><span style="font-size: x-small;"><a href="http://journals.ametsoc.org/doi/abs/10.1175/1520-0485(1975)005%3C0450:FOTDTI%3E2.0.CO;2">Wyrtki, Klaus</a>. "Fluctuations of the dynamic topography in the Pacific Ocean."Journal of Physical Oceanography 5.3 (1975): 450-459.</span></li>
</ul>
Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com3tag:blogger.com,1999:blog-4996769537501094384.post-42996491121403784632014-03-26T18:48:00.000+01:002020-02-27T13:40:31.504+01:0049 Open Challenges in Earth Science - The Known Unknowns<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><span style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><a href="http://mappingignorance.org/category/science/geosciences/"><img border="0" src="https://2.bp.blogspot.com/-Ylb7dcUV6nU/UvJHw876gZI/AAAAAAAAZHE/omI-TPytxPc/s1600/5c01fe87a5a6e84ca07359e2f3fbe99b_bigger.png" /></a></span></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b><a href="http://mappingignorance.org/category/science/geosciences/">Mapping Ignorance</a></b></td></tr>
</tbody></table>
<span style="float: left; padding: 5px;"><a href="http://www.researchblogging.org/"><img alt="ResearchBlogging.org" src="https://www.researchblogging.org/public/citation_icons/rb2_large_gray.png" style="border: 0px;"></a></span><br />
What keeps Earth scientists busy? These 49 open scientific questions aim at providing an updated, fully-referenced account of the main current scientific questions, disputes, and challenges in Geoscience.<br />
<br />
<br />
<br />
<b><br /></b>
<b>[<a href="http://retosterricolas.blogspot.com/p/open-questions-in-geoscience.html">updated version in this link</a>]</b><br />
<b><br /></b>
<br />
<div>
<div>
<div>
<h3>
<b>The Early Earth and the Solar System</b></h3>
<div class="separator" style="clear: both; text-align: center;">
</div>
<div>
Advances such as those occurred in the geochemistry of meteorites lead to new exciting hypotheses about the early stages of our planet, but as usual, answers are outnumbered by the new knowledge gaps: </div>
<div class="separator" style="clear: both; text-align: center;">
<a href="http://4.bp.blogspot.com/-til41l5DAOw/UteezlPALYI/AAAAAAAAY6E/WrYQh82tiN0/s1600/Theia+collision.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="126" src="https://4.bp.blogspot.com/-til41l5DAOw/UteezlPALYI/AAAAAAAAY6E/WrYQh82tiN0/s1600/Theia+collision.png" width="200" /></a></div>
<ol>
<li>How did the Earth and other planets form? Were planets formed <i>in situ</i>? Or are orbital changes relatively frequent? What determined the different deep layering of the solar planets?<span style="font-size: x-small;"> </span><span style="font-size: xx-small;">[McKinnon, 2012, <a href="http://www.sciencemag.org/content/336/6078/162.summary"><i>Science</i></a> on Mercury] </span></li>
<li>Was there ever a collision of the Earth with another planet Theia, giving birth to our satellite? <span style="font-size: xx-small;">[<a href="http://www.sciencemag.org/content/338/6110/1052.abstract">Canup, 2013, <i>Science</i></a>]</span> There is compelling evidence, such as <a href="http://archives.datapages.com/data/cspg_sp/data/016/016001/161_cspgsp0160161.htm">measures of a shorter duration of the Earth's rotation and lunar month</a> in the past, pointing to a Moon much closer to Earth during the early stages of the Solar System.<span style="font-size: xx-small;"> [<a href="http://archives.datapages.com/data/cspg_sp/data/016/016001/161_cspgsp0160161.htm">Williams, <i>CSPG Spec. Pubs.,</i> 1991</a>]</span></li>
<li>What is the long-term heat balance of Earth? How did its internal temperature decay since it formed by accretion of chondrites? How abundant are radiogenic elements in the interior? Did a "<a href="http://news.discovery.com/space/was-earth-a-migratory-planet-120418.html">faint young sun</a>" ever warm a "snowball Earth"?<span style="font-size: xx-small;"> [<i><a href="http://wiredcosmos.com/2013/10/04/climate-puzzle-over-origins-of-life-on-earth/">Wired</a></i>; <a href="http://www.sciencemag.org/content/342/6154/101">Marty et al., 2013, <i>Science</i></a>]</span></li>
<li>What made plate tectonics a dominant process only on Earth?<span style="font-size: x-small;"> </span><span style="font-size: xx-small;">[<a href="http://www.leitzelcenter.unh.edu/geo-teach/pdf/ESST2008/Johnson-MartinetalPlateTectonics.pdf">outreach paper</a>]</span> How did the planet cool down before plate tectonics?<span style="font-size: xx-small;">[<a href="http://www.nature.com/nature/journal/v501/n7468/full/nature12473.html">Moore & Webb, 2013, <i>Nature</i></a>]</span> Was the Earth's crust formed during the early stages of its evolution or is it the result of a gradual <i>distillation</i> of the mantle that continues today along with crustal recycling? Is the crust still growing or does its recycling compensate for crust formation at mid-ocean ridges and other volcanic areas?</li>
<li>How inherent to planetary evolution is the development of life conditions?<span style="font-size: x-small;"> </span><span style="font-size: xx-small;">[<a href="http://www.sciencemag.org/content/309/5731/89.full">Zimmer, 2005, <i>Science</i></a>, <a href="http://www.nature.com/nature/journal/v497/n7451/full/497570a.html?utm_source=feedly#auth-1">Elkins-Tanton</a><u>, 2013, <i>Nature</i></u></span><span style="font-size: xx-small;">]</span> Earth-like planets are now known to be abundant in our galaxy (two out of three stars may have one <span style="font-size: xx-small;">[e.g., <a href="http://www.nature.com/nature/journal/v481/n7380/full/nature10684.html"><span style="color: black;">Cassan et al., 2012, <i>N</i></span><i>ature</i></a>]</span>), but how many of them develop widespread durable water chemistry? How much of our water supplied by comets or asteroids? When and how did it reach the Earth? <span style="font-size: xx-small;">[<a href="http://www.smithsonianmag.com/science-nature/how-did-water-come-to-earth-72037248/?no-ist">outreach article</a>]</span></li>
</ol>
<h3>
<b>Earth’s Interior</b></h3>
<div>
<div>
Our rock-sampling reach is limited to the upper 12 km of the Earth's crust, but the keys to extend our knowledge often lay far deeper than that. Indirect measurements such as seismic wave tomography, together with geodynamic and petrological modeling, become crucial: </div>
</div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<div class="separator" style="clear: both; text-align: center;">
<a href="http://www.burkemuseum.org/static/geo_history_wa/The%20Restless%20Earth%20v.2.0_files/image006.gif" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://www.burkemuseum.org/static/geo_history_wa/The%20Restless%20Earth%20v.2.0_files/image006.gif" height="200" width="200"></a></div>
<ol>
<li>What are the chemical composition and mechanical properties of rocks in the Earth’s mantle at the extreme pressure and temperature they undergo? As planets age and cool off, their internal and surface processes coevolve, chemically and mechanically, shaping also the atmospheric composition. Therefore this question has direct implications for our understanding of the environmental evolution of the Earth. <span style="font-size: xx-small;">[<a href="http://www.sciencemag.org/content/309/5731/87.full"><span lang="EN-GB" style="font-family: "calibri"; line-height: 115%;">Kerr,
2005, Science</span></a>]</span></li>
<li>What are the dynamic processes in the Earth interior that accommodate and fuel plate tectonics? As seismometers spread more evenly over the planet's surface, the seismic imaging of the interior will rapidly improve, providing a detailed distribution of seismic wave velocity. Simultaneously, lab-based mineral physics must better constrain what these mechanical wave velocities tell us about the hot, deep rocks of uncertain composition in the mantle. Only then will computer models be able to test the proposed geodynamic models by trying to fit quantitatively those data and other geophysical observations such as gravity variations. <span style="font-size: xx-small;">[<a href="http://www.sciencemag.org/content/309/5731/87.full">ref.3</a>]</span></li>
<li><span lang="EN-US">Sedimentary and volcanic rocks have recorded changes of the magnetic field throughout the evolution of the Earth. What causes the sudden <a href="http://retosterricolas.blogspot.com/2012/03/seafloor-spreading-hypotheses-and.html">reversals</a> of the paleomagnetic field? How does the geomagnetic field link to the iron convection properties at the deep Earth? Or inversely, what can we learn about the mechanical behavior of the materials at those depths from the geomagnetic field? <span style="font-size: xx-small;">[more context in <a href="http://www.nature.com/nature/journal/v485/n7398/full/485319a.html">Nature</a>]</span> Are the magnetic reversals too fast to be related to core dynamics?<span style="font-size: x-small;"> </span><span style="font-size: xx-small;">[</span></span><span style="font-size: xx-small;"><a href="http://www.physorg.com/news202971192.html">example.1</a>] [<a href="http://retosterricolas.blogspot.com/2012/03/seafloor-spreading-hypotheses-and.html">ex.2</a>] [<a href="http://www.nature.com/ngeo/journal/v5/n8/full/ngeo1521.html">ex.3</a>]</span> Could their frequency be related to the <span style="background-color: white; text-align: justify;">distribution of tectonic plates? <span style="font-size: xx-small;">[</span></span><span style="font-size: xx-small;"><a href="http://t.co/z2QZnvU9" style="background-color: white; text-align: justify;">GRL</a> article]</span>. What causes superchrons (periods longer than 10 Myr without magnetic reversals)? Something internal to the core, or induced externally by the mantle/subducting slabs? Was the geomagnetic field always dipolar, or was it more asymmetric in the past? <span style="font-size: xx-small;">[<a href="http://phys.org/news/2012-07-links-magnetic-field-inversions-mantle.html#nRlv">introduction</a>]</span></li>
<li>Are intraplate hotspots really made by deep sources of uprising materials (mantle plumes) coming from the deepest Earth's mantle? Or can they be explained by shallower convection? <span style="font-size: xx-small;">[e.g., <a href="http://www.nature.com/nature/journal/v230/n5288/abs/230042a0.html">Morgan, 1971</a>; see also this recent <i>Geology</i> paper on <a href="http://geology.gsapubs.org/content/40/5/479.full?rss=1">Yellowstone</a>]</span>.</li>
<li>What is the history of and what controls the excursions of the rotation pole relative to the surface geography, known as true polar wander? <span style="font-size: xx-small;">[<a href="http://www.nature.com/nature/journal/v491/n7423/full/nature11571.html">ex</a>]</span></li>
<li>What are the properties of deep rocks? How can we translate the heterogeneity in density, seismic wave velocity, or electromagnetic resistivity presently observed in the mantle and the lithosphere into variations of the mineralogical composition? And how do these measures relate to the dynamics of the Earth and to key mechanical properties such as the viscosity? <span style="font-size: xx-small;">[<span lang="EN-GB" style="font-family: "calibri"; line-height: 115%;"><a href="http://www.nature.com/nature/journal/v465/n7298/full/nature09064.html">Faccenna
& Becker, 210, Nature</a></span><span lang="EN-GB" style="font-family: "calibri"; line-height: 115%;">]. </span></span></li>
<li>What are the causes for Large Igneous Provinces and massive flood basalts such as the Columbia River Basalts?</li>
</ol>
<h3>
<b>Tectonic-plate motion and deformation </b></h3>
The successful adoption of the plate tectonics paradigm has lead to a myriad of new questions about its limits and about the lessons for risk mitigation.<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="http://www.tectonics.caltech.edu/outreach/highlights/2008MayChinaEQ/figs/velocity.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="" border="0" src="https://www.tectonics.caltech.edu/outreach/highlights/2008MayChinaEQ/figs/velocity.jpg" height="280" title="GPS motion measurements in Asia" width="320"></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div style="font-size: 12.727272033691406px;">
Velocity of the earth's surface at the Indian-Asian collision,</div>
<div style="font-size: 12.727272033691406px;">
from GPS data. Blue star indicates the 2008 China earthquake.</div>
<span style="font-size: xx-small;">Source: <a href="https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=14&cad=rja&ved=0CGoQFjAN&url=http%3A%2F%2Fwww.tectonics.caltech.edu%2Foutreach%2Fhighlights%2Fseasonal_eq%2F&ei=MbaLUZHFGsag7Ab65oGQCA&usg=AFQjCNFc0kbCXmHgt8OuqMCdV5nPiTIUkw&sig2=nIDWwRqFe3Z7DGLtOzMlgQ">CALTECH</a></span></td></tr>
</tbody></table>
<ol start="1" style="margin-top: 0cm;" type="1">
<li>What is the relative importance of the forces driving plate tectonics: slab pull, slab suction, mantle drag, and ridge push? <span style="font-size: xx-small;">[e.g., Conrad & </span><span style="font-size: xx-small;">Lithgow-</span><span style="font-size: xx-small;">Bertelloni, 2004; Negredo et al., </span><a href="http://www.agu.org/pubs/crossref/2004/2003GL019315.shtml" style="font-size: x-small;">GRL, 2004</a><span style="font-size: xx-small;">, vs. van Benthem & Govers, </span><a href="http://www.agu.org/pubs/crossref/2010/2009JB006950.shtml" style="font-size: x-small;">JGR, 2010</a><span style="font-size: xx-small;">]</span><span style="font-size: x-small;">.</span><span style="font-size: xx-small;"> </span>What is the force balance and the geochemical cycle in subduction zones? <span style="font-size: xx-small;">[<a href="http://onlinelibrary.wiley.com/doi/10.1002/2013JB010718/suppinfo">Emry et al., 2014, JGR</a>]</span><span style="font-size: xx-small;"> </span>How much water (and how deep) penetrates into the mantle?<a href="http://www.nature.com/nature/journal/v425/n6956/abs/nature01961.html"> <span style="font-size: xx-small;">[Ranero et al., 2003, Nature]</span></a><span style="font-size: xx-small;"> </span>How much subcontinental erosion takes place under subduction areas? <span style="font-size: xx-small;">[<a href="http://www.nature.com/nature/journal/v404/n6779/abs/404748a0.html">Ranero et al., 2000, Nature</a>]</span></li>
<li>What happens after the collision of two continents? Does continental collision diminish the rate of plate subduction, as suggested by the slab-pull paradigm? <span style="font-size: xx-small;">[Alvarez, <a href="http://www.sciencedirect.com/science/article/pii/S0012821X10003481">EPSL, 2010</a>] </span>How frequent are the processes of <a href="http://en.wikipedia.org/wiki/Delamination_(geology)">mantle delamination</a> and slab break-off? What determines their occurrence?<span style="font-size: xx-small;"> [Magni et al., <a href="http://onlinelibrary.wiley.com/doi/10.1002/grl.50090/abstract">GRL, 2013</a>; Durezt & Gerya, <a href="http://www.sciencedirect.com/science/article/pii/S0040195113000061">Tectonoph., 2013</a>]</span></li>
<li>Why are orogens curved when seen from space? <span style="font-size: xx-small;">[<a href="http://specialpapers.gsapubs.org/content/383/1.full.pdf">Weil & Sussman, 2004, GSASP 383</a>]</span></li>
<li>How does the long-term deformation derived from paleomagnetism and structural geology link quantitatively to the present-day motions derived from GPS and from neotectonic patterns of crustal deformation?<span style="font-size: x-small;"> </span><span style="font-size: xx-small;">[Calais et al., EPSL, 2003]</span> How do these last two relate to each other? <span style="font-size: xx-small;">[<a href="http://www.nature.com/nature/journal/v484/n7394/full/nature11032.html">ref</a>]</span> Can we learn from regional structure of the crust/lithosphere from that link (or viceversa)? </li>
<li>Are plate interiors moving in steady-state linear motion? How rigid are these and why/when did they deform? <span style="font-size: xx-small;">[Davis et al., (2005) doi:10.1038/nature04781, and Wernicke & Davis, (2010) doi:10.1785/gssrl.81.5.694]</span>. </li>
<li class="MsoNormal">How is the relative motion between continents accommodated in <a href="http://geology.about.com/od/platetectonicmaps/ss/Plate-Boundaries-Map.htm">diffuse plate boundaries</a>? (eg., the Iberian/African plate boundary). What determines the (a)seismicity of a plate contact? </li>
<li>How/when does deformation propagate from the plate boundaries into plate interiors?<span style="font-size: x-small;"> </span><span style="font-size: xx-small;">[e.g., <a href="http://cuba.ictja.csic.es/~danielgc/papers/Cloetingh%20et%20al.,%202005,%20QSR.pdf">Cloetingh et al., 2005, QSR</a>]</span><span style="font-size: x-small;"> </span></li>
<li class="MsoNormal">What is the rheological stratification of the lithosphere: like a <i>jelly sandwich</i>? Or rather like a <i>creme brulée</i>?<span style="font-size: x-small;"> </span><span style="font-size: xx-small;">[Burov & Watts, 2006]</span>. Is the lower crust ductile? Is strength concentrated at the uppermost mantle? Or just the other way around?<span style="font-size: x-small;"> </span><span style="font-size: xx-small;">[e.g., <a href="http://onlinelibrary.wiley.com/doi/10.1029/1999JB900446/abstract">McKenzie et al., 2000, JGR</a>; <a href="http://www.geosociety.org/gsatoday/archive/12/9/pdf/i1052-5173-12-9-4.pdf">Jackson, 2002, GSA Today</a>; <a href="http://www.geo.fu-berlin.de/geol/fachrichtungen/geologie/mitarbeiter/mhandy/Publication_PDF/Handy_Brun04_EPSL.pdf">Handy & Brun, 2004</a>; and a nice <a href="http://all-geo.org/metageologist/2012/04/creme-brulee-or-jelly-sandwich/">recent post</a>]</span>. </li>
<li class="MsoNormal"><span lang="EN-US"><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://upload.wikimedia.org/wikipedia/commons/thumb/1/13/Interactions_and_feedback_pathways_for_tectonics_and_erosional_processes.pdf/page1-1200px-Interactions_and_feedback_pathways_for_tectonics_and_erosional_processes.pdf.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="180" src="https://upload.wikimedia.org/wikipedia/commons/thumb/1/13/Interactions_and_feedback_pathways_for_tectonics_and_erosional_processes.pdf/page1-1200px-Interactions_and_feedback_pathways_for_tectonics_and_erosional_processes.pdf.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.7272720336914px; text-align: center;">Add caption</td></tr>
</tbody></table>
<ol start="1" style="margin-top: 0cm;" type="1"></ol>
Does the climate-controlled erosion and surface transport of sediment modify the patterns of tectonic deformation? <span style="text-align: justify;">Does vigorous erosion cause localized deformation in the core of mountain belts and prevent the propagation of tectonic shortening into the undeformed forelands? </span><span style="text-align: justify;">Does the deposition of sediment on the flank of mountains stop the frontal advance of the orogen?</span> Is there any field evidence for these effects predicted from computer models?<span style="font-size: x-small;"> </span><span style="font-size: xx-small;">[<a href="http://earth-literally.blogspot.com.es/2011/12/underground-truth-experiments-models.html">Philip Allen's blog</a>] [<a href="http://onlinelibrary.wiley.com/doi/10.1029/1999JB900248/abstract">Willett, 1999, JGR</a>; <a href="http://www.nature.com/ngeo/journal/v2/n2/abs/ngeo413.html">Whipple, 2009</a>; <a href="https://docs.google.com/uc?id=0B_xuyENh5ksFMzdiZjg0NGUtNWQ5Zi00YTU0LThkODctODA3ZWMxYjAzNTI2&export=download&hl=en">Garcia-Castellanos, EPSL, 2007</a>]</span></span></li>
<li class="MsoNormal"><span lang="EN-US">Can earthquakes be predicted? <span style="font-size: xx-small;">[<a href="http://retosterricolas.blogspot.com/2011/09/ionospheric-electron-enhancement.html">Heki, 2011, GRL</a>; <a href="http://www.nature.com/ngeo/journal/v5/n6/full/ngeo1489.html">Freed, 2012, Nat.Geosc</a><u>.</u>]</span>. How far away can they be mechanically triggered?<span style="font-size: xx-small;"> [<a href="http://www.nature.com/nature/journal/v424/n6951/full/nature01903.html">Tibi et al., 2003, Nature</a>]</span>. Little is known about how faults form and when do they reactivate <span style="font-size: xx-small;">[<a href="http://phys.org/news/2011-11-earthquakes-lubricant.html">ex.6</a>]</span></span>, and even worse, there seems to be no clear pathway as to solve this problem in the near future. Unexpected breakthroughs needed. </li>
<li class="MsoNormal" style="text-align: justify;">How can the prediction of volcanic eruptions be improved? What determines the rates of magma accumulation in the chamber and what mechanisms make magmas eruptible? <span style="font-size: xx-small;">[<a href="http://pubs.usgs.gov/pp/1788/">ex.7</a>][<a href="http://www.nature.com/nature/journal/v491/n7425/full/491498a.html">ex.7b</a>]</span></li>
<li class="MsoNormal">In many regions, the elevation of the continents does not match the predictions from the classical <a href="http://en.wikipedia.org/wiki/Isostasy">principle of isostasy</a> for the Earth's outer rigid layer (the lithosphere). This deviation is known as <i>dynamic topography</i>, by opposition to <i>isostatic topography</i>. But what are the mechanisms responsible? Can we learn about the mantle dynamics by estimating dynamic topography? <span style="font-size: x-small;">[<a href="http://www.nature.com/ngeo/journal/v3/n12/full/ngeo1020.html">ref.1</a>] </span>Can the <i>hidden loads</i> needed to explain the accumulation of sediment next to orogens (<i>foreland basins</i>) be linked to these dynamic forces? <span style="font-size: xx-small;">[<a href="http://eu.wiley.com/WileyCDA/WileyTitle/productCd-1405194650.html">Busby & Azor, 2012, Wiley</a>]</span></li>
<li class="MsoNormal" style="text-align: justify;">How do land-forming processes react to climate change at a variety of scales, ranging from the Milankovitch cycles to the late Cenozoic cooling of the Earth? Is there a feedback from erosion into climate at these time scales, through the Carbon cycle and the weathering of silicates, for example? What is the role of the surface uplift and erosion of Tibet on the drawdown of atmospheric CO<span class="s1">2 </span>over the Cenozoic?<span style="font-size: xx-small;"> [Garzione, 2008, Geology]</span></li>
</ol>
<h3>
<b><span style="line-height: 1.5;">Earth's landscape history and present environment</span></b></h3>
The shape of the planet's solid surface, its topography, is the key feature that connects many of the disciplines within Earth science, probably because it is the feature that most affects our daily life. It is today common wisdom that landscape forms from a complex interplay between tectonics and climate, through a list of mechanical, chemical, and biological processes acting at the surface of the Solid Earth. Topographic data is becoming now available at resolutions finer than a few meters, and the sedimentary record is also being archived at unprecedented rates. But:<br />
<div style="text-align: right;">
</div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-lO3Tbn-AC3k/UtelCzgizSI/AAAAAAAAY6U/_Dm4cX2l1Kk/s1600/Yarlung+Tsangpo+River,+China,+drainage+pattern+NASA+PIA03708_modest.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="240" src="https://2.bp.blogspot.com/-lO3Tbn-AC3k/UtelCzgizSI/AAAAAAAAY6U/_Dm4cX2l1Kk/s1600/Yarlung+Tsangpo+River,+China,+drainage+pattern+NASA+PIA03708_modest.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.727272033691406px; text-align: center;">Drainage patterns in Yarlung Tsangpo River, China (NASA)</td></tr>
</tbody></table>
<ol start="1" style="margin-top: 0cm;" type="1"><a href="http://2.bp.blogspot.com/-lO3Tbn-AC3k/UtelCzgizSI/AAAAAAAAY6U/_Dm4cX2l1Kk/s1600/Yarlung+Tsangpo+River,+China,+drainage+pattern+NASA+PIA03708_modest.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em; text-align: center;"><br /></a>
<li class="MsoNormal" style="text-align: justify;"><span lang="EN-US" style="text-align: -webkit-auto;">Can we use these data to derive past tectonic and climatic conditions? Will we ever know enough about the erosion and transport processes? Was also the stocasticity of meteorological and tectonic events relevant in the resulting landscape? </span><span style="text-align: -webkit-auto;">And how much has life contributed to shape the Earth's surface? </span></li>
<li class="MsoNormal"><span style="text-align: -webkit-auto;">Can classical geomorphological concepts such as 'peneplanation' or 'retrogressive erosion' be understood quantitatively? Old mountain ranges such as the Appalachian or the Urals s</span>eem to retain relief for > 10^8 years, while fluvial valleys under the Antarctica are preserved under moving ice of kilometric thickness since the Neogene. What controls the time-scale of topographic decay? <span style="font-size: xx-small;">[<a href="http://www.nature.com/nature/journal/v498/n7455/full/nature12218.html">Egholm, 2013, <i>Nature</i></a>]</span></li>
<li class="MsoNormal">What are the erosion and transport laws governing the evolution of the Earth’s Surface?<span style="font-size: xx-small;">[<a href="http://geology.gsapubs.org/content/early/2013/01/04/G33918.1.abstract">Willenbring et al., <i>Geology</i>, 2013</a>]</span> Rivers transport sediment particles that are at the same time the tools for erosion but also the shield protecting the bedrock. How important is this double role of sediment for the evolution of landscapes? <span style="font-size: xx-small;">[<a href="http://eps.berkeley.edu/~bill/papers/105.pdf">Sklar & Dietrich, Geology, 2001</a> (tools and cover effect); <a href="http://www.geos.ed.ac.uk/research/globalchange/group3/Apenninesproj/Cowie_et_al_2008.pdf">Cowie et al., Geology, 2008</a> (a field example)]</span>.</li>
<li class="MsoNormal">Can we predict sediment production and transport for hazard and scientific purposes? <span style="font-size: xx-small;">[<a href="http://download.nap.edu/cart/download.cgi?&record_id=12700&free=1">NAS SP report, 2010</a>; <a href="http://geology.gsapubs.org/content/early/2013/01/04/G33918.1.abstract"><i>Geology</i>, 2013</a>]</span> </li>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="http://web.mit.edu/perron/www/images/gabilan_spacing.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://web.mit.edu/perron/www/images/gabilan_spacing.jpg"></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.7272720336914px; text-align: center;">Smaller-scale patterns at the limit<br />
between river channels and hillslopes.<br />
Credit: Perron Group, MIT</td></tr>
</tbody></table>
<li class="MsoNormal">What do th<span lang="EN-US" style="background-color: white;">e preserved 4D patterns of sediment flow tell us from the past of the Earth? Is it possible to quantitatively link past climatic and tectonic records to the present landforms? Is it possible to separate the signals of both processes?<span style="font-size: x-small;"> </span><span style="font-size: xx-small;">[e.g., </span></span><span lang="EN-US" style="background-color: white; font-size: xx-small;"><a href="http://www.nature.com/ngeo/journal/v4/n4/full/ngeo1087.html"><i>Armitage et al., 2011, Nature Geosc</i></a>]</span><span style="background-color: white;">.</span><span lang="EN-US" style="background-color: white;"> </span></li>
<li class="MsoNormal" style="text-align: justify;"><span lang="EN-US" style="text-align: -webkit-auto;">Can we differentiate changes in the tectonic and climate regimes as recorded in sediment stratigraphy? Some think both signals are indeed distinguishable<span style="font-size: xx-small;"> [<a href="https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&sqi=2&ved=0CDEQFjAA&url=http%3A%2F%2Fwww.nature.com%2Fngeo%2Fjournal%2Fv4%2Fn4%2Ffull%2Fngeo1087.html&ei=h5ssUe62AZOyhAfUsYHIBQ&usg=AFQjCNH25xwC2oY4s6MS2wNU-S225NuYKg&sig2=Ql6tkTUzNEW3e_lHVZGLyQ&bvm=bv.42965579,d.d2k">Armitage et al., 2011</a>, Nat.Geo.]</span>. Others (<a href="http://www.agu.org/pubs/crossref/2010/2010GL044638.shtml"><span style="font-size: xx-small;">Jerolmack & Paola, </span></a><span style="font-size: xx-small;"><a href="http://www.agu.org/pubs/crossref/2010/2010GL044638.shtml">2010, GRL</a>]</span>, argue that the dynamics intrinsic to the sediment transport system can be 'noisy' enough to drown out any signal of an external forcing. </span></li>
<li class="MsoNormal" style="text-align: justify;">Does surface erosion draw hot rock towards the Earth’s surface? Do tectonic folds grow preferentially where rivers cut down through them, causing them to look like up-turned boats with a deep transverse incision?<span style="font-size: xx-small;"> [<a href="http://geology.gsapubs.org/content/32/4/341.short">Simpson, 2004, <i>Geology</i></a>]</span></li>
<li class="MsoNormal" style="text-align: justify;"><span style="text-align: left;">How resilient is the ocean to chemical perturbations? </span>What caused the huge salt deposition in the Mediterranean known as the <a href="http://en.wikipedia.org/wiki/Messinian_salinity_crisis">Messinian Salinity Crisis</a>? Was the Mediterranean truly desiccated? What were the effects on climate and biology, and what can we learn from extreme salt giants like this?<span style="font-size: x-small;"> </span><span style="font-size: xx-small;">[e.g., <a href="http://www.amazon.com/The-Mediterranean-Was-Desert-Challenger/dp/0691024065">Hsu, 1983</a>; <a href="http://geology.gsapubs.org/content/24/4/363.abstract">Clauzon et al., <i>Geology</i>, 1996</a>; <a href="http://www.nature.com/nature/journal/v400/n6745/abs/400652a0.html">Krijgsman et al, 1999, <i>Nature</i></a>; <a href="https://docs.google.com/uc?id=0B_xuyENh5ksFN2MwYWE5YjUtNzNkOS00OGZlLWFkMDYtOWMxYTViYjRiZjc0&export=download&hl=en">Garcia-Castellanos & Villaseñor, <i>Nature</i>, 2011</a>]</span>. Were the normal marine conditions truly reestablished by the largest flood documented on Earth, 5.3 million years ago?<span style="font-size: xx-small;"> [<a href="http://www.nature.com/nature/journal/v462/n7274/abs/nature08555.html">Garcia-Castellanos et al., 2009, <i>Nature</i></a>]<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-7TRkDAtxmVk/VE5HsRvPKNI/AAAAAAAAduw/MRU3i9lLN1M/s1600/Roger%2BPibernat%2B-%2Blandscape%2B-%2Bmessi_med-1024x768%2Bauthors.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="240" src="https://2.bp.blogspot.com/-7TRkDAtxmVk/VE5HsRvPKNI/AAAAAAAAduw/MRU3i9lLN1M/s1600/Roger%2BPibernat%2B-%2Blandscape%2B-%2Bmessi_med-1024x768%2Bauthors.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div style="font-size: 12.7272720336914px;">
Artistic view of the refilll of the</div>
<div style="font-size: 12.7272720336914px;">
Mediterranean after the Messinian salinity</div>
<div style="font-size: 12.7272720336914px;">
crisis. Authors: Pibernat & Garcia-Castellanos.</div>
<div style="font-size: 12.7272720336914px;">
Downloadable <a href="http://cuba.ictja.csic.es/~danielgc/share/Mediterranean/RogerPibernat-Mediterranean-flood-1024x768.jpg">here</a>.</div>
</td></tr>
</tbody></table>
</span></li>
<li class="MsoNormal" style="text-align: justify;">How do the patterns of river networks form? <span style="font-size: xx-small;">[eg. <span style="color: #4c4c4c; font-family: "helvetica neue" , "arial"; text-align: left;"><a href="http://www.pnas.org/content/109/51/20832.full">Devauchelle et al., 2012, <i>PNAS</i></a>; <a href="http://www.nature.com/nature/journal/v492/n7427/full/nature11672.html">Perron et al., 2012, <i>Nature</i></a></span>].</span> And what information about the past do these patterns contain? Can we quantitatively reconstruct past ecology or climate from old river patterns? <span style="font-size: xx-small;">[e.g., <a href="http://jsedres.geoscienceworld.org/content/80/2/167.abstract"><i><span style="color: black; font-style: normal;">Hartley et al., 2010, J</span>. Sedim. Res</i>.</a>]</span></li>
<li>Do we need a new geological epoch called Anthropocene? When do the Homo Sapiens start to have a significant impact on the Earth System? 8000 BP?<span style="font-size: xx-small;">[<a href="http://stephenschneider.stanford.edu/Publications/PDF_Papers/Ruddiman2003.pdf">Ruddiman, 2003, Climatic Change</a>]</span>; 2000 BP? <span style="font-size: xx-small;">[<a href="http://hol.sagepub.com/content/early/2011/07/19/0959683611408454.abstract">Scalenghe, 2011, The Holocene</a>]</span>; 1850 AD? <span style="font-size: xx-small;">[<a href="http://stephenschneider.stanford.edu/Publications/PDF_Papers/CrutzenSteffen2003.pdf">Crutzen & Steffen, 2003</a>]</span></li>
</ol>
<div>
<span style="font-size: xx-small;"><span style="line-height: 13.63636302947998px;"><br /></span></span></div>
<h3>
<b>Climate, Life, and Earth</b></h3>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="http://ww2.tnstate.edu/ganter/65_Myr_Climate_Change.png" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://ww2.tnstate.edu/ganter/65_Myr_Climate_Change.png" height="195" width="320"></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Source: <a href="https://commons.wikimedia.org/wiki/File:65_Myr_Climate_Change.png">R.E..Rhode, Wikipedia</a></td></tr>
</tbody></table>
The geological record shows that climate is relatively stable over tectonic time-scales whereas it undergoes abrupt changes in periods ranging from decades to hundreds of thousand years. Past periods when the planet underwent extreme climate conditions may help to understand the mechanisms behind that behavior and its significance for the evolution of the Solid Earth.<br />
<br />
<ol start="1" style="margin-top: 0cm;" type="1">
<li class="MsoNormal">What caused the largest carbon isotope changes in Earth? <span style="font-size: xx-small;">[<a href="http://www.nature.com/ngeo/journal/v4/n5/full/ngeo1138.html#auth-1">Grotzinger</a> et al., 2011, Nat. Geosc.]</span><span style="font-size: x-small;"> </span>How does Earth’s climate system respond to elevated levels of atmospheric CO2? </li>
<li class="MsoNormal"><span lang="EN-US">Was there ever a <a href="http://en.wikipedia.org/wiki/Snowball_Earth">snow-ball Earth</a> during the earliest stages of Life on Earth? </span></li>
<li class="MsoNormal">Were there also rivers and lakes on Mars? <span style="font-size: xx-small;"><a href="http://www.nature.com/news/dreams-of-water-on-mars-evaporate-1.10412">[Hans, 2012]</a></span> Were there large <a href="http://retosterricolas.blogspot.com/2012/02/megafloods-gradualism-and-birth-of.html">outburst floods similar to those on Earth</a>? </li>
<li class="MsoNormal"><span style="background-color: white;">What were the causes and what shaped the recovery from mass extinctions as those at the K-T boundary, the Permian-Triassic or the Late Triassic? Massive volcanism? Meteorites? Microbes?</span><span style="background-color: white; font-size: x-small;"> </span><span style="background-color: white; font-size: xx-small;">[recent papers: <a href="http://geology.gsapubs.org/content/40/5/e267.full?rss=1">ex.8</a>, <a href="http://geology.gsapubs.org/content/40/6/531.abstract?rss=1">ex.9</a>, <a href="http://www.nature.com/ngeo/journal/v5/n6/full/ngeo1475.html">ex.10</a>, <a href="http://newsoffice.mit.edu/2014/ancient-whodunit-may-be-solved-microbes-did-it">Rothman et al., 2014, PNAS</a>]</span></li>
<li class="MsoNormal"><span lang="EN-US">What triggered the extreme climatic variability during the Quaternary and the roughly coeval acceleration in continental erosion and sediment delivery to the margins? <span style="font-size: xx-small;">[<a href="http://www.nature.com/nature/journal/v410/n6831/abs/410891a0.html">Peizhen, Molnar et al., 2001, Nature</a>; <a href="http://www.nature.com/nature/journal/v504/n7480/full/nature12877.html">Herman et al., 2013, Nature</a>] </span>Was this related to the tectonic closure of the Central American Seaway? How do these climate events translate quantitatively into sea level changes?</span></li>
<li style="line-height: 1.5;">How do climate changes translate quantitatively into sea level changes? <span style="line-height: normal;">How do ice sheets and sea level respond to a warming climate? What controls regional patterns of precipitation, such as those associated with monsoons or El Niño?</span></li>
<li class="MsoNormal"><span lang="EN-US">What caused the <a href="http://en.wikipedia.org/wiki/Quaternary_extinction_event">Quaternary extinction(s)</a>? Human expansion? Climate Change? How sensitive are ecosystems and biodiversity to environmental change? Was the large fauna extinction ~13,000 yr ago a result of the Younger Dryas climatic event? Was this caused by an extraterrestrial impact? <span style="font-size: xx-small;">[<a href="http://phys.org/news/2012-04-evidence-prehistoric-extraterrestrial-impact-event.html">ex.11</a>, <a href="http://phys.org/news/2012-06-evidence-theory-extraterrestrial-impact.html">ex.12</a>]</span> Or may it be linked to the outburst of <a href="http://phys.org/news/2011-10-long-lost-lake-agassiz-clues-climate.html">Lake Agassiz</a>? </span></li>
<li class="MsoNormal"><span style="background-color: white;">How relevant are subsurface microorganisms to earth dynamics by controlling soil formation and the methane c</span>ycle? What are the origin, composition, and global significance of deep subseafloor communities? What are the limits of life in the subseafloor realm? <!--EndFragment--></li>
<li class="MsoNormal">The atmosphere is shaped by the presence of life, a powerful chemical force. The Earth’s evolution has seems to affect the evolution of life <span style="font-size: xx-small;">[see the <a href="http://phys.org/tags/cambrian+explosion/">Cambrian explosion</a> of animal life, for instance; plus this recent <a href="http://phys.org/news/2012-04-great-unconformity-evidence-geologic-trigger.html">paper</a> on that]</span>. To what extent? And how much control has life on climate?<span style="font-size: xx-small;"> [another <a href="http://www.nature.com/nature/journal/v485/n7399/full/485452a.html">recent one</a>]</span><span style="font-size: x-small;">.</span> Is it possible to quantify these links to make reliable predictions that allow filling the data gaps or assessing the chances for extraterrestrial life?</li>
<li class="MsoNormal">How much of the present climate change is anthropogenic? How will growing emissions from a growing global population with a growing consumption impact on climate? </li>
</ol>
<div>
<h3>
<b>Broader open questions</b></h3>
<div class="separator" style="clear: both; text-align: center;">
<a href="http://geology.gsapubs.org/content/40/5/451/F2.large.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><br /></a></div>
<ol start="1" style="margin-top: 0cm;" type="1"><a href="http://upload.wikimedia.org/wikipedia/commons/b/bc/SurfaceTemperature.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em; text-align: center;"><img border="0" src="https://upload.wikimedia.org/wikipedia/commons/b/bc/SurfaceTemperature.jpg" height="100" width="200"></a><a href="http://geology.gsapubs.org/content/40/5/451/F2.large.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em; text-align: center;"><img border="0" src="https://geology.gsapubs.org/content/40/5/451/F2.large.jpg" height="145" width="200"></a><a href="http://upload.wikimedia.org/wikipedia/commons/b/bc/SurfaceTemperature.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em; text-align: center;"><br /></a><a href="http://geology.gsapubs.org/content/40/5/451/F2.large.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em; text-align: center;"><br /></a>
<li class="MsoNormal">Many of the questions above are related to the extreme diversity of spatial scales of Earth processes. Direct observation (by sampling or remotely) is mostly limited to a thin layer around the solid surface of the Earth, and physical experimentation is limited to the pressures of the uppermost layers of the planet. Many processes including plate tectonics are known to be driven by the nature of the materials that make up the planet interiors, down to the smallest atomic scales, as thought for instance for the trigger of earthquakes. Answers may arrive via new devices and analytical tools working at the high pressures and temperatures of Earth’s interior.</li>
<li class="MsoNormal">Time scales also pose a problem to know the mechanical and chemical properties of Earth's materials. Partly because we deal with time scales in very different orders of magnitude while we are limited to make observations from the present. But also because scaling the rates of lab experiments (e.g., mineral physics) or analogue models (e.g., sandbox experiments) with the corresponding geological scenarios is not always convincing. </li>
<li class="MsoNormal"><span lang="EN-US">Implementing Episodicity in Gradualism: For historical reasons, geology has generally <a href="http://retosterricolas.blogspot.com/2012/02/megafloods-gradualism-and-birth-of.html">underestimated the role of episodicity</a> in nature. However, there is a growing view that exceptional events and stochasticity have a relevant role in many of Earth's subsystems. An example for this is the preeminence of flooding events (larger than average) in erosion and surface sediment transport and during the evolution of landscape, and the importance of upscaling flood stochasticity into sediment transport models <span style="font-size: xx-small;">[eg., Lague, 2010, JGR]</span>. Climate variability at all time-scales has been already mentioned above. Even plate tectonics may have been episodic (during the Archean at least, <span style="font-size: xx-small;">[<a href="http://geology.gsapubs.org/content/40/5/451.abstract?rss=1">ref</a>]</span>). 4D hyperscale data sets in geomorphology are increasingly showing the limits of <i>smooth-process</i> approaches. Future understanding of the Earth will benefit from incorporating the full frequency spectrum (the episodicity) in modeling natural phenomena, rather than systematically approaching these as gradual processes. </span></li>
<li class="MsoNormal">Computer models tell whether the complexity of nature can be explained by the interplay between simple processes, but: how can we further model the Earth as a complex system of complex systems? And when can we expect ‘compact’ explanations? </li>
</ol>
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<br /></div>
</div>
<div>
<b>General background:</b></div>
<ol start="1" style="margin-top: 0cm;" type="1"></ol>
</div>
Note that the specific references given above for each open question are sometimes just examples and may not always be the best representative. Furthermore, the list is surely biased towards Solid Earth Science, my own field. The following general references can give you an alternative perspective on the subject.</div>
<div>
<ul>
<li>BESR (2008). Origin and Evolution of Earth: Research Questions for a Changing Planet The National Academies Press DOI: <a href="http://dx.doi.org/10.1002/gj.1188">10.1002/gj.1188</a></li>
<li><a href="http://www.sciencemag.org/content/309/5731/78.2.full">Science 125th anniv.</a> <a href="http://www.sciencemag.org/content/309/5731/78.2.full">compilation</a>.</li>
<li>NAS report Origin and evolution of Earth [<a href="http://dels.nas.edu/resources/static-assets/materials-based-on-reports/reports-in-brief/origin_and_evolution_of_earth_final.pdf">pdf</a>] [<a href="http://dels.nas.edu/Report/Origin-Evolution-Earth-Research/12161">html</a>]</li>
<li><a href="http://dels.nas.edu/resources/static-assets/materials-based-on-reports/reports-in-brief/earth_surface_processes_final.pdf">NAS report</a> on surface processes</li>
<li>Earth Magazine 2012 <a href="http://www.earthmagazine.org/article/five-outstanding-questions-earth-science">article</a>.</li>
</ul>
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Please send additions/suggestions to d.g.c@csic.es</div>
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<div style="margin-bottom: 1.5em;">
<b>Acknowledgements:</b><br />
For various inputs/criticisms to this list: <a href="https://twitter.com/clasticdetritus">Brian Romans</a>, <a href="https://twitter.com/Umba_moxos">Umberto Lombardo</a>, Jean Braun, Mikael Attal, Alexandra Witze, Michael Klaas, Matt Hall, Chris Rowan.</div>
PD: I published a shorter version of this post in <a href="http://mappingignorance.org/category/science/geosciences/"><i>Mapping Ignorance</i></a>. -Daniel</div>
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Daniel Garcia-Castellanoshttp://www.blogger.com/profile/02249835207972834131noreply@blogger.com0ICTJA, 08028 Barcelona, Spain41.384508639947867 2.119401769159594641.38153013994787 2.1143592691595945 41.387487139947865 2.1244442691595946