[cwmma]

if we're nitpicking, glaciers push down the crust they are on (https://en.wikipedia.org/wiki/Isostatic_depression) so when glaciers melt the land underneath is at first underwater before emerging

[bediger4000]

Hardly nitpicking. The size of the two glacial lakes was phenomenal, bigger than current great lakes. Glacial lake Missoula emptying into the Pacific dug out the Channeled Scablands in Washington State.