Historical:Little Bear Soil
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
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