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Summary
The geology of Kansas is classic, from the cyclic sedimentation of the east to the marine vertebrates in the chalk beds of the west, but it seems to be largely misunderstood by those who have not looked at the rocks carefully. The phrase "layer cake," commonly applied to the Carboniferous and Permian rocks in the eastern third of Kansas, is well known. Rarely recognized is the fact that the accumulation of these layers was discontinuous. Flooding events, or surfaces of subaerial exposure, often separate the layers. Flooding surfaces may contain evidence of colonization by boring and/or encrusting marine invertebrates before they were buried by subsequent sedimentation. Exposure surfaces may contain evidence of soil development and associated plant debris that may be subsequently reworked and buried by marine sedimentation. These genetic surfaces sometimes cut across lithologic layers, with each genetic layer a possible facies mosaic that contains subtle evidence of a number of different environments. Some of the thick mudrock units between limestones in the Kansas Permian contain evidence of numerous paleosols, and in many cases, may represent much more time than the marine limestones that have received the most attention by geologists. The alternation between 1) marine carbonates and siliciclastics, 2) flooding and subaerial exposure surfaces, and 3) climate changes are hallmarks of Permian rocks in Kansas. A simple bathymetric model does not explain this alternation, or cyclicity; such a model is inadequate to explain and understand the complexities of these cyclic sequences. The rocks are recording a much more complicated sequence of events, a complexity that offers exciting challenges for anyone interested. Great opportunities are found through a multi-disciplinary approach to test new and different models and add to a better understanding of this important period, which ended with the greatest mass extinction event in earth history.
Forty-five years ago a Kansas geologist told me "we know all there is to know about the geology of Kansas." We now know that this statement was not true for the Permian in Kansas, and we are still far from knowing it all. It is important to remember that "If you think you have all the answers then you're not up to date on all the questions." All scientific endeavors are just "a work in progress," as is this, "The Permian System in Kansas."
Acknowledgments
This paper was written at the invitation of the Kansas Geological Survey, and we thank them for their confidence. We are indebted to a number of people at that organization for encouragement and support. Rex Buchanan and Bob Sawin read many drafts and made many useful comments. Sawin, in particular, has been a very consistent and helpful critic. Marla Adkins-Heljeson did her usual outstanding job of editing, and Janice Sorensen assisted in literature aquisition. The numerous graphics are the result of the excellent work of Jennifer Sims (now retired). Tom Olszewski, Texas A&M University, and Sal Mazzullo, Wichita State University, reviewed an earlier version and Tom Olszewski's comments and suggestions were especially pertinent and helpful. We are grateful and appreciative of the efforts of all these people.
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Kansas Geological Survey, Geology
Placed on web April 27, 2010; originally published April 2010.
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