Willman, H. B., Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, and Jack A. Simon, 1975, Handbook of Illinois Stratigraphy: Illinois State Geological Survey Bulletin 95, 261 p.
H. B. Willman and T. C. Buschbach
Gunter Sandstone (Ball and Smith, 1903, p. 26).
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.
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.
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.
Well log characteristics
Age and correlation
The Gunter is tentatively correlated with the Rose Run Sandstone at the base of the upper Knox in eastern Ohio and eastern Kentucky.
Environments of deposition
BALL, S. H., and A. F. SMITH, 1903, Geology of Miller County: Missouri Bureau of Geology and Mines (2), v. 1, 207 p.
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