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Chemung Formation (redefined as Foreknobs Formation) (VADch;0)

Geologic Formation in VA, KY, WV

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Lithology

Conglomerate

Sandstone

Shale

Geologic Age

Devonian (422.4 Ma – 359.3 Ma ago)

Geologic Unit Label

Dch

Chemung Formation (Hall, 1839). Redefined as the Foreknobs Formation (Dennison, 1970). Sandstone and shale, dark-gray and greenish-gray, fine-grained, thin- to thick-bedded, lithic sandstone and interbedded greenish gray, fissile, clay shale. Minor quartz-pebble conglomerate, thin red sandstone, and locally, fossil shell beds. Very thin or absent in southwestern Virginia; thickens to about 2500 feet northeastward in Frederick County. Gradational contact with underlying Brallier Formation and equivalent to part of the Chattanooga Shale to the southwest. Redefined and described as part of the Greenland Gap Group by Dennison (1970).

— USGS