Outside the region covered by this paper, the most notable exposure of this formation occurs at Crawfordsville, Indiana, where its thickness is said to be two hundred and eighty feet. South of the Iowa line, exposures occur along the Mississippi in limited areas, and southwestward in Missouri, yielding most of the lead in that region.
Proceedings of the Iowa Academy of Sciences
©1889 Iowa Academy of Science, Inc.
Gordon, C. H.
"On the Keokuk Beds and Their Contained Fossils in the Vicinity of Keokuk, Iowa,"
Proceedings of the Iowa Academy of Science, 1(Pt. 1), 98-100.
Available at: https://scholarworks.uni.edu/pias/vol1/iss1/47