At http://phys.org/print370089048.html … an unusual geological landform in Wabash River Valley in southern Illinois has attracted attention. This is a scarp, or cliff edge running 10 to 20 feet in height and proceeds in a straight line for six miles. The scarp runs perfectly parallel with a fault line one mile to the west and it has always been assumed the two features were related. What geologists found instead was no relationship whatsoever – which caused them to think things through again. How many other geological features are interpreted on assumption without any kind of field investigation.
They have reached the conclusion it was formed by rapid erosion and the only thing with enough power and force was a flood surge. Layers in the sediments below the scarp seem to date back to flooding events at the end of the Late Glacial Maximum. As the ice sheet melted lakes formed at the edge and these discharged in a series of catastrophic flooding events. A glacier may have existed not far from the Wabash River valley as after all the Great Lakes begin in northern Illinois. These are generally thought to be formed from outfloor from the melting ice sheet. A wall of water must have swept down the valley, possibly disgorging itself eventually in the Mississippi River system and found its way into the Gulf of Mexico. It may have happened once – or several times. It does mean the ice sheet melted rapidly – very quickly in fact. That might fit into a scenario involving pole movement – but could the global temperatures actually go up enough in a short space of time. That is what the ice core people think occurred.