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"Chemung" Formation, Parkhead Sandstone, Brallier Formation, and Harrell Shale

"Chemung" Formation - Predominantly marine beds characterized by gray to olive-green graywacke, siltstone, and shale; thickened ranges from 2,000 to 3,000 feet; Parkhead Sandstone - Gray to olive-green sandy shale, conglomeratic sandstone and graywacke; present in Washington County, identification uncertain in west; thickness averages 400 feet; Brallier Fomation - (Woodmont Shale of earlier reports). Medium to dark gray, laminated shale and siltstone; weathers to light olive-gray; grain size coarsens upward; thickness about 2,000 feet in west, about 1,7000 feet in east; and Harrell Shale - Dark gray laminated shale; absent in east where Brallier lies directly on Mahantango, Tully Limestone lies near base in west, in subsurface of Garrett County; total thickness in west 140 to 300 feet.
StateMaryland
Name"Chemung" Formation, Parkhead Sandstone, Brallier Formation, and Harrell Shale
Geologic ageDevonian
Original map labelDch
Comments"Chemung", Parkhead, Brallier, and Harrell Formations formerly were designated as Jennings Formation.
Primary rock typeshale
Secondary rock typesiltstone
Other rock typessandstone; graywacke; limestone
Lithologic constituents
Major
Sedimentary > Clastic > Siltstone
Sedimentary > Clastic > Mudstone > Shale
Minor
Sedimentary > Clastic > Sandstonelocally conglomeratic
Sedimentary > Clastic > Sandstone > Graywacke
Incidental
Sedimentary > Carbonate > Limestone
Map references
Cleaves, E.T., Edwards, J., Jr., Glaser, J.D., 1968, Geologic Map of Maryland: Maryland Geological Survey, Baltimore, Maryland, scale 1:250,000.
Unit references
Cleaves, E.T., Edwards, J., Jr., Glaser, J.D., 1968, Geologic Map of Maryland: Maryland Geological Survey, Baltimore, Maryland, scale 1:250,000.
Unpublished digital version of the Maryland state geologic map that was digitized by the USGS Water Resources Office in Towson, MD
USGS Geologic Names Lexicon (GEOLEX)
Geographic coverageAllegany - Garrett - Washington

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