Geology
The Flint Hills were created approximately 250 million years ago during the Permian Period. During this time much of the Midwest, including Kansas and Oklahoma, were covered with shallow seas. As a result, much of the Flint Hills are composed of limestone and shale with plentiful fossils of prehistoric sea creatures. The most notable layer of chert-bearing limestone is the Florence Limestone Member. It is approximately 45 feet thick; numerous roadcuts of the Florence Member are prominent along Interstate 70 in Riley County, Kansas. Many of the honey-colored limestones have been used for building blocks. The non-chert-bearing limestones are best for this, since the chert is extremely hard to cut, yet it can fracture quite easily.
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