Historical:Gunter Sandstone

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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: Knox Dolomite Megagroup >>Prairie du Chien Group >>Gunter Sandstone
Chronostratigraphy: Paleozoic Erathem >>Ordovician System >>Canadian Series >>Trempealeauan Stage
Allostratigraphy: Sauk Sequence

Authors

H. B. Willman and T. C. Buschbach

Name Origin

The Gunter Sandstone (Ball and Smith, 1903, p. 26) is named for the now abandoned Gunter post office in Miller County, central Missouri, where it is 2.5-18 feet thick in exposures along the Osage River.

Correlation

The Gunter is tentatively correlated with the Rose Run Sandstone at the base of the upper Knox in eastern Ohio and eastern Kentucky.

Extent and Thickness

It is absent in outcrops of lower Prairie du Chien strata in Lee and Ogle Counties, Illinois. In subsurface, the Gunter is commonly a few to 20 feet thick and has a widespread but patchy distribution (fig. O-9). It is continuous and 10-25 feet thick between the centers of La Salle and McLean Counties in north-central Illinois.

Description

The Gunter consists of medium- to fine-grained, moderately sorted, subrounded quartz grains. It contains thin beds of light gray, fine-grained dolomite and small amounts of green shale. Sharp contacts and irregular distribution of the sandstone suggest unconformities at its top and bottom.

References

BALL, S. H., and A. F. SMITH, 1903, Geology of Miller County: Missouri Bureau of Geology and Mines (2), v. 1, 207 p.

ISGS Codes

Stratigraphic Code Geo Unit Designation
8480
Os