Gunpowder Granite

Remobilized Baltimore Gneiss. Fine- to medium-grained quartz monzonite with biotitic schlieren; grades into Baltimore Gneiss in core of Towson dome; age 550 +/- 50 m.y. * by radiogenic dating.
State Maryland
Name Gunpowder Granite
Geologic age Paleozoic
Lithologic constituents
Igneous > Plutonic > Syenitic > Quartz-monzonite
Comments Radiogenic date from Wetherill et al., 1966 - ref. MD003). Also a revised age of 450 m. y. (ref. MD004)

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

Wetherill, G.W., Tilton, G.R., Davis, G.L., Hart, S.R., and Hopson, C.A., 1966, Age measurements in the Maryland Piedmont: Journal of Geophysical Research, v. 71, p. 2139-2155.

USGS Geologic Names lexicon found at:

NGMDB product
Counties Baltimore - Baltimore