Iowa's mid-continental location has made its area one of the last to be reached by the successive marine invasions from the Cambrian on. A quantitative study of the length of post-Cambrian time during which Iowa has been land versus the length of time it has been more or less a sea floor is offered.
Proceedings of the Iowa Academy of Science
©1929 Iowa Academy of Science, Inc.
Thomas, A. O.
"A Review of the Time Factor Represented by the Stratigraphic Breaks in the Iowa Geological Column,"
Proceedings of the Iowa Academy of Science, 36(1), 280-280.
Available at: https://scholarworks.uni.edu/pias/vol36/iss1/72