Martinsburg Formation

Upper part rhythmically interbedded graywackes, siltstones, and dark shales; lower part dark brown, dark gray, and black, thin-bedded fissile shale; thickness 2,000 to 2,500 feet.
State Maryland
Name Martinsburg Formation
Geologic age Ordovician
Lithologic constituents
Major
Sedimentary > Clastic > Mudstone > Shale
Sedimentary > Clastic > Sandstone > Graywacke
Minor
Sedimentary > Clastic > Siltstone
References

Cleaves, E.T., Edwards, J., Jr., and Glaser, J.D., 1968, Geologic Map of Maryland: Maryland Geological Survey, Baltimore, Maryland, scale 1:250,000.

In 1995 the Water Resources Division of the U.S. Geological Survey digitized the geologic map of Maryland from the 1968 paper map (Reference MD001). Information about products from the Maryland Geological Survey can be found at http://www.mgs.md.gov/.

NGMDB product
Counties Washington