| Council Grove Group | |
|---|---|
| Stratigraphic range: Carboniferous-Permian boundary[1] | |
| Type | Group |
| Sub-units | Speiser Shale Funston Limestone |
| Underlies | Chase Group |
| Overlies | Admire Group |
| Location | |
| Region | Midcontinent (Kansas, Nebraska, Oklahoma, Colorado (subsurface) ) |
| Country | United States |
| Type section | |
| Named for | Council Grove, Kansas |
The Council Grove Group is a geologic group in Kansas, Oklahoma, and Nebraska as well as subsurface Colorado. It preserves fossils dating to the Carboniferous-Permian boundary.[1][2] This group forms the foundations and lower ranges of the Flint Hills of Kansas, underlying the Chase Group that forms the highest ridges of the Flint Hills.
The Group particularly consists of megaclycothems alternating between massive mudstone paleosols and massive shallow marine limestone. The sequences of these alternations correlate with the ~400,000 year component of Milankovitch cycles. A number of the limestones have minor flint-filled marine animal burrows, anticipating the massive flint beds of the Chase Group.
With the exposure of the group's lower formations in the 1993 flooding,[3] the entirety of the Council Grove Group, from hillcrest Speiser Shale down to pond-level Americus limestone, is exposed for study from top to bottom in the Tuttle Creek Lake Spillway.[4]
See also
References
- 1 2 Robert S. Sawin, Ronald R. West, Evan K. Franseen, W. Lynn Watney (January 2006). "Carboniferous-Permian Boundary in Kansas, Midcontinent, U.S.A". Current Research in Earth Sciences. 252 (1).
... the Carboniferous-Permian boundary in Kansas can now be confidently defined. Based [on fossil changes, the] boundary in Kansas can be placed at the base of the Bennett Shale Member of the Red Eagle Limestone.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ↑ "Geologic Unit: Council Grove". National Geologic Database. Geolex — Unit Summary. United States Geological Survey. Retrieved 2019-06-02.
- ↑ David Mathews, Vlad G. Perlea, Francke C. Walberg, Douglas R. Anderson (U.S. Army Corps of Engineers, Kansas City, Missouri) (1998). "Erosion and Repair of Unlined Spillway Chute Excavated in Rock". International Conference on Case Histories in Geotechnical Engineering. Missouri University of Science and Technology. Retrieved 2019-06-01.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ↑ "Pottawatomie County T. 9 S., R. 8 E." Kansas Geological Survey. Retrieved 2019-06-02.
Further reading
- Melville R. Mudge and Ellis L. Yochelson (1962). "Stratigraphy and Paleontology of the Uppermost Pennsylvanian and Lowermost Permian Rocks in Kansas" (PDF) (323). USGS Professional Paper. Retrieved 2021-11-27.
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- This report encyclopedically covers the units exposed in the Tuttle Creek Lake Project area, predominantly the lower Permian.