Until recently little definite information has been accessible concerning the distribution and subdivisions of the Cretaceous deposits of Northwestern Iowa. Strata of Cretaceous age have been recognized from time to time at various points, but, as a rule, little detailed information has been recorded. As early as 1840 Nicollet called attention to certain sections near the mouth of the Sioux River which he regarded as Cretaceous in age. Since that time Cappellini, Marcou, Meek, Hayden, White and others have been through this region. In all these cases the rocks noted were in the immediate vicinity of the Missouri River. White gave more attention, perhaps, to the Iowa strata than any of the other writers mentioned, and recognized outliers as far east as Guthrie County and as far south as Montgomery County.
Proceedings of the Iowa Academy of Sciences
©1893 Iowa Academy of Science, Inc.
Keyes, Charles R.
"Cretaceous Formations of Northwestern Iowa,"
Proceedings of the Iowa Academy of Science, 1(Pt. 4), 24-25.
Available at: https://scholarworks.uni.edu/pias/vol1/iss4/10