The ancient channel which it held along the Illinoian ice front has been traced through southeastern Iowa for many miles.
A captive balloon was used in making investigations of the ice front.
Within a few miles of the ice front the stones still have a fresh aspect.
During this period, the drainage was ponded between the ice front and the Umpog-Saugatuck divide.
Earlier positions of the ice front are marked by equally large moraines.
In valley glaciers it is shaped by the ice front to a crescent whose convex side is downstream.
Temporary lakes were formed wherever the ice front dammed the natural drainage of the region.