Taxonomy of Iowa\u27s Glacial Deposits

From the angle of genesis we lately have to modify some of our ideas on our Glacial till-sheets. Realizing that the continental ice-masses do not emanate from a single center, it is found that our Iowa tills come from what is known as the Keewatin center, on the west of Hudson Bay; while the tills on the east side of the Mississippi River originated mainly from the Labradoran center. The only invasion of ice from the last mentioned center is a slight one by the Illinoian ice, in the extreme southeastern part of our state