Historical:Aux Vases Sandstone
Elwood Atherton, Charles Collinson, and Jerry A. Lineback
The Aux Vases Sandstone (Keyes, 1892, p. 295) is named for the Aux Vases River in Ste. Genevieve County, Missouri.
The type section of the Aux Vases Sandstone consists of outcrops in the Mississippi River bluffs at the mouth of the Aux Vases River (N1/2 NW1/4 13, 37N-9E).
Extent and Thickness
The Aux Vases occurs in much of the area of the Chesterian Series (fig. M-23). It crops out along the Mississippi River Valley in St. Clair, Monroe, and Randolph Counties, being particularly well exposed in the bluffs 2-3 miles southeast of Prairie du Rocher, Randolph County. In southern Illinois it crops out principally in Union, Johnson, and Hardin Counties. The thickness map of the Aux Vases (fig. M-23) shows discontinuities because in some areas the base is dropped to include the equivalents of the underlying Joppa Member of the Ste. Genevieve Limestone where the Joppa grades to sandstone and shale. In a much smaller area, the base is dropped to include equivalents of the Spar Mountain Sandstone Member where the Karnak Member lenses out or grades to sandstone (Swann and Atherton, 1948; Swann, 1963). In the area where the Joppa Member is present, all of the Aux Vases is assigned to the Rosiclare Sandstone Member. In southeastern Illinois the Aux Vases is commonly 20-40 feet thick, but north and west of there, where it includes Joppa equivalents, it is 60-80 feet thick. It thickens to the west and reaches a maximum of 130-160 feet in the small area where it includes Joppa and Spar Mountain equivalents.
The Aux Vases consists of sandstone, siltstone, and minor amounts of shale and, locally, dolomite and limestone. The sandstone is light gray to greenish gray, locally pink or red, hematitic, calcareous, very fine to fine grained. In many places it grades to coarse siltstone. Lenses of brown dolomite occur in the lower part. The shale in the Aux Vases is dark gray and sandy, and the siltstone is green or gray. Where it includes Joppa equivalents, the Aux Vases commonly contains beds or lenses of gray, yellow, brown, pink, or red oolitic limestone.
KEYES, C. R., 1892, Principal Mississippian section: Geological Society of America Bulletin, v. 3, p. 283-300.
SWANN, D. H., 1963, Classification of Genevievian and Chesterian (Late Mississippian) rocks of Illinois: Illinois State Geological Survey Report of Investigations 216, 91 p.
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.
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