The Council Grove Group is a geologic group in

Kansas Kansas () is a state in the Midwestern United States. Its capital is Topeka, and its largest city is Wichita. Kansas is a landlocked state bordered by Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to ...

, Oklahoma, and

Nebraska Nebraska () is a state in the Midwestern region of the United States. It is bordered by South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the so ...

as well as subsurface

Colorado Colorado (, other variants) is a state in the Mountain states, Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the wes ...

. It preserves

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

dating to the Carboniferous-

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Pale ...

boundary. This group forms the foundations and lower ranges of the

Flint Hills The Flint Hills, historically known as Bluestem Pastures or Blue Stem Hills, are a region in eastern Kansas and north-central Oklahoma named for the abundant residual flint eroded from the bedrock that lies near or at the surface. It consists ...

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 Milankovitch cycles describe the collective effects of changes in the Earth's movements on its climate over thousands of years. The term was coined and named after Serbian geophysicist and astronomer Milutin Milanković. In the 1920s, he hypot ...

. 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, 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.

See also

References

Further reading