Rockdale Run Formation

Upper one-third gray, mottled, cherty dolomite and dolomitic limestone; lower two-thirds gray, cherty argillaceous calcarenite and algal limestone with interbedded dolomite and oolitic limestone; thickness at least 1,700 feet east of Conococheague Creek, increases to about 2,500 feet in west.
State Maryland
Name Rockdale Run Formation
Geologic age Ordovician
Lithologic constituents
Major
Sedimentary > Carbonate > Dolostone
Sedimentary > Carbonate > Limestone
Minor
Sedimentary > Clastic > Sandstone > Arenite > Calcarenite
Stratigraphic units Beckmantown Group
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