Historical:Little Bear Soil

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Handbook of Illinois Stratigraphy
Series Bulletin 95
Author H. B. Willman, Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, Jack A. Simon
Date 1975
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Lithostratigraphy: Tuscaloosa Formation >>Little Bear Soil
Chronostratigraphy: Mesozoic Erathem >>Cretaceous System

Authors

H. B. Willman and John C. Frye

Name Origin

The Little Bear Soil (Mellen, 1937, p. 8-20), a soil locally preserved at the base of the Cretaceous System, is named for Little Bear Creek, Tishomingo County, Mississippi.

Type Section

It is well exposed along the Post Creek Cutoff in Pulaski County (cen. 2, 15S-2E), where it is 7 feet thick, rests on the St. Louis Limestone, and is overlain by gravel of the Tuscaloosa Formation.

Extent and Thickness

Isolated remnants have been found throughout the eastern part of the Mississippi Embayment.

Stratigraphic Position

The Little Bear Soil is included in the lower part of the Tuscaloosa Formation.

Description

It is the only soil-stratigraphic unit that has been named in Illinois in pre-Quaternary strata (Pryor and Ross, 1962; Ross, 1963). It consists of remnants of an iron-rich residual soil developed on Paleozoic rocks. In Illinois it consists of red and brown clays with lenses and nodules of brown to black limonite and, generally, a few angular chert pebbles. The Little Bear Soil was developed during early Cretaceous time, after the erosional truncation of the Paleozoic rocks by the sub-Cretaceous unconformity.

References

MELLEN, F. F., 1937, Little Bear residuum: Mississippi Geological Survey Bulletin 34, 36 p.
PRYOR, W. A., and C. A. ROSS, 1962, Geology of the Illinois parts of the Cairo, La Center, and Thebes Quadrangles: Illinois State Geological Survey Circular 332, 39 p.
ROSS, C. A., 1963, Structural framework of southernmost Illinois: Illinois State Geological Survey Circular 351, 27 p.

ISGS Codes

Stratigraphic Code Geo Unit Designation
1450
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