Large granite erratics, formerly attributed to the Iowan, are believed to be associated with the Kansan drift. Now located within valleys, they have remained after considerable Kansan till has been eroded.
Proceedings of the Iowa Academy of Science
©1959 Iowa Academy of Science, Inc.
Tuttle, Sherwood D.
"Large Erratics in Jasper County, Iowa,"
Proceedings of the Iowa Academy of Science, 66(1), 280-282.
Available at: https://scholarworks.uni.edu/pias/vol66/iss1/40