Lithostratigraphy: Pope Megagroup >>West Baden Group >>Paint Creek Group >>Bethel Sandstone
Chronostratigraphy: Paleozoic Erathem >>Mississippian Subsystem >>Chesterian Series >>Gasperian Stage
Allostratigraphy: Kaskaskia Sequence
Elwood Atherton, Charles Collinson, and Jerry A. Lineback
The Bethel Sandstone (Butts, 1917, p. 63-64) is named for Bethel School, 3.5 miles west of Marion, Crittenden County, Kentucky.
Extent and Thickness
The Bethel is 20-40 feet thick in much of its northwestern area (fig. M-35), but locally it is thinned by pre-Cypress erosion. The formation thickens to the southeast, reaching just over 100 feet in eastern Gallatin County.
The Bethel is dominantly sandstone in much of Illinois, but it grades to shale to the west. The sandstone of the Bethel is, in general, the coarsest grained of the Chesterian sandstones. Locally, it includes a few small quartz pebbles and a basal conglomerate of limestone and shale pebbles. Most of the sandstone is light gray to light greenish gray, but a few thin lenses are green or medium gray. Dark greenish gray shale partings are common, and some contain carbon and mica flakes. As the sandstone grades westward to shale, red and green shales become more noticeable. Along the outcrop belt in southwestern Illinois, a persistent bed of deep red, structureless clay about 15 feet thick is prominent.
In places, numerous fragmentary plant fossils, including Lepidodendron, are present.
BUTTS, CHARLES, 1917, Descriptions and correlations of the Mississippian formations of western Kentucky, Part I of Mississippian formations of western Kentucky: Kentucky Geological Survey, v. 1, 119 p.
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