Elwood Atherton, Charles Collinson, and Jerry A. Lineback
The Yankeetown Sandstone (S. Weller, 1913, p. 120) is named for Yankeetown School, Monroe County.
The type section of the Yankeetown Sandstone is located near Yankeetown School (NE cor. SE 26, 4S-9W) and consists of cherty sandstone grading to chert.
Extent and Thickness
Although only about 20 feet thick in the outcrop area, it can be traced northeastward into the upper part of a thick sandstone in Washington County, where it is separated by a thin limestone (Renault) from the Aux Vases Sandstone below. As thus differentiated, the Yankeetown Sandstone includes sandstone and shale formerly regarded as being in the upper part of the Renault. The Yankeetown is about 60 feet thick in much of the central part of its extent (fig. M-33). To the north it thins to less than 20 feet, and to the south and southwest it thickens in places to a little over 100 feet.
The Yankeetown is a sandstone-shale unit in western Illinois that grades into a limestone-shale unit in eastern Illinois. Red shale is extensively developed near the top of the Yankeetown, but other shales present are dark greenish gray, green, and variegated. The sandstone is much like that in the Bethel, mainly white or light gray to light greenish gray, very fine, angular, and incoherent. Chert occurs only in, and close to, the western outcrop belt. Southeastward the sandstone facies changes to a limestone-shale facies, the change occurring near the northwestern corner of Hamilton County (Swann and Atherton, 1948). At about the same place, the Bethel Sandstone, which is predominantly shale to the northwest, becomes predominantly sandstone to the southeast, which misled many into thinking that the Bethel and Yankeetown were equivalent (fig. M-7). The sandstone of the Yankeetown was commonly called "Benoist," and the names "Benoist" and "Bethel" were mistakenly regarded as being interchangeable. In the limestone-shale facies, most of the shales are dark greenish gray and green, with some red in the upper part. The limestones are light gray, buff, brown, or gray. Some are oolitic, some crinoidal, some silty, and some lithographic.
SWANN, D. H., and ELWOOD ATHERTON, 1948, Subsurface correlations of lower Chester strata of the Eastern Interior Basin, in Symposium on problems of Mississippian stratigraphy and correlation: Journal of Geology, v. 56, p. 269-287; Illinois State Geological Survey Report of Investigations 135.
WELLER, STUART, 1913, Stratigraphy of the Chester Group in southwestern Illinois: Illinois Academy of Science Transactions, v. 6, p. 118-129.
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