The Sheffield formation is found in north central Iowa lying unconformably on the Owen limestone of Upper Devonian age and unconformably below the Hampton formation of Kinderhook age. The region in which the Sheffield is best exposed is in northeastern Franklin County within the area of the Iowan drift. The drift is thin enough in this area to reflect the underlying rock surface. The soft nature of the Sheffield material has allowed the streams to curve out a mature rolling topography in this portion of the county. Because of the thin Iowan drift the exposures of the Sheffield are found near the tops of the hills as well as in the beds of the streams. The drainage of this area is east into Shell Rock River.
Proceedings of the Iowa Academy of Science
© Copyright 1930 by the Iowa Academy of Science, Inc.
Laudon, Lowell Robert
"A Spirifer disjunctus Fauna in Iowa,"
Proceedings of the Iowa Academy of Science, 37(1), 251-254.
Available at: https://scholarworks.uni.edu/pias/vol37/iss1/53