Lake Bonneville was an enormous closed lake (meaning it had no outlet) encompassing the western half of Utah during the Pleistocene. The Great Salt Lake is a small remnant. It would be among the few largest, deepest, and highest lakes today. When its level raised to 1500 m above sea level at the end of the last glaciation, 15,000 years ago, its waters found an exit through the Red Rock pass and the lake was suddenly drained. It produced one of the largest floods ever recorded: the Bonneville Flood (see this previous post). But there was another consequence to the flood: When the lake water was released, the lithosphere under the lake moved upwards to readjust its isostatic equilibrium with the viscous mantle that underlies the Earth's crust.
Now, do you believe this story?