Pocono Group, including the Purslane Sandstone and Rockwell Formation

Pocono Group - Gray, white, tan, and brown, thin- to thick-bedded, cross-bedded sandstone, locally conglomeratic; interbedded gray and reddish-brown shale, mudstone, and siltstone; fragmentary plant fossils. Undifferentiated in Garrett and western Allegeny Counties. Includes Purslane Sandstone - White, thick-bedded, coarse-grained sandstone and conglomerate with thin coal beds and red shales. Eastern Allegany and Washington Counties. And also inlcudes Rockwell Formation - Coarse-grained arkosic sandstone, fine-grained conglomerate, and buff shale; dark shale with thin coal beds near base. Eastern Allegany and Washington Counties.
State Maryland
Name Pocono Group, including the Purslane Sandstone and Rockwell Formation
Geologic age Mississippian
Lithologic constituents
Major
Sedimentary > Clastic > SandstoneGray, white, tan, and brown, thin- to thick-bedded, cross-bedded sandstone
Minor
Sedimentary > Clastic > Mudstone > Shaleinterbedded gray and reddish-brown shale, mudstone, and siltstone
Sedimentary > Clastic > Mudstoneinterbedded gray and reddish-brown shale, mudstone, and siltstone
Sedimentary > Clastic > Siltstoneinterbedded gray and reddish-brown shale, mudstone, and siltstone
Incidental
Sedimentary > Clastic > Conglomerate
Sedimentary > Coal
Comments Total thickness of Group is 250 feet in west, increases to 1,700 feet in east.
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 Allegany - Garrett - Washington