Chilhowee Group; Loudoun Formation

Basal phyllite member: Pale purple, discontinuous, lenticular; members are in gradational contact; total thickness 0 to 200 feet
State Maryland
Name Chilhowee Group; Loudoun Formation
Geologic age Cambrian
Lithologic constituents
Metamorphic > Metasedimentary > Metaclastic > Phyllite
Stratigraphic units Chilhowee Group

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

NGMDB product
Counties Frederick - Washington