There are at least two pre-glacial valleys in Lee County, which is situated in the extreme southeast corner of the state of Iowa, the first running nearly parallel to the present course of the Mississippi, and the other roughly parallel with the valley of the Des Moines. These valleys were once occupied by great mid-continental streams, whose geological age has never been fully determined. Their waters eroded channels several miles in width through the indurated rocks of the Carboniferous, over which they passed, to a depth considerably below the present grade of the water courses with which they are analogous.
Proceedings of the Iowa Academy of Science
©1923 Iowa Academy of Science, Inc.
Wilson, Ben H.
"An Excellent Example of High Clay Bank Erosion in Lee County, Iowa,"
Proceedings of the Iowa Academy of Science, 30(1), 425-431.
Available at: https://scholarworks.uni.edu/pias/vol30/iss1/68