Geology of Kansas
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There are three eras that make up surface rocks in Kansas, they consist of the Paleozoic, Mesozoic and Cenozoic. Paleozoic rocks at the surface in Kansas are primarily from the Mississippian, Pennsylvanian and Permian periods.
The oldest rocks at the surface in Kansas are Mississippian rocks that consist of limestones, shale, dolomite, chert, sandstones and siltstones. The Mississippian consisted of an environment similar to what we see today. Fast moving streams and rivers cutting into the limestone bedrock and in places creating caverns and sinkholes (Buchanan, 1984). Pennsylvanian rocks consist predominantly of alternating marine and non-marine shales and limestones with some sandstone, coal, chert and conglomerate. The Pennsylvanian was a time that the region that is now eastern Kansas stayed nearly at sea level. Between the transgression and regression of the seas, swamps and bogs formed, depositing dead vegetation and later, after burial under younger sediments, this dead vegetation formed into coal (Buchanan, 1984). Permian rocks predominantly consist of limestones, shales and evaporates. The Permian in Kansas began as an environment consisting of warm, shallow seas. As the Permian progressed, the climate became very dry and the seas began to subside, creating bodies of water shut off from the open seas, in turn creating areas for the generation of dark shales and evaporates like salt and gypsum as the waters evaporated (Buchanan, 1984). The end of the Permian marks the largest extinction period in Earth's history; over 90% of all life disappeared.
Mesozoic rocks at the surface in Kansas consist of rocks from only one period, the Cretaceous. Cretaceous age rocks consist of limestone, chalk, shale and sandstone. The Cretaceous in Kansas was an open ocean or sea environment dominated by microscopic marine plants and animals that floated or swam near the surface of this ancient water body (Buchanan, 1984). As these microscopic creatures died they sank to the bottom, formed a soft, limy ooze and would preserve any larger creatures that would die and sink into it.
Cenozoic rocks at the surface are made up of the Tertiary and Quaternary periods. Tertiary rocks in Kansas consist of river silt, sand, freshwater limestones and some volcanic ash derived from eruptions in the western United States. Near the beginning of the Tertiary, the Rocky Mountains were born, as were the streams and rivers heading eastward out the mountains into Kansas. Over 60 million years of erosion, the Rocky Mountains created a wedge of material extending to the Flint Hills of eastern Kansas (Buchanan, 1984). Quaternary rocks in Kansas consist glacial drift; river silt, sand and gravel; dune sand and wind blown silt. The Quaternary Period in western Kansas was very similar to the Tertiary, continual erosion off the Rocky Mountains, depositing more sediments (Buchanan,1984).
[edit] References
- Buchanan, R., Kansas Geology: An Introduction to Landscapes, Rock, Minerals, and Fossils. University Press of Kansas. p. 208.
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