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Mineral Resources On-Line Spatial Data

Potomac Group, including Raritan and Patapsco Formations, Arundel Clay, and Patuxent Formation

Potomac Group - Interbedded quartzose gravels; protoquartzitic to orthoquartzitic argillaceous sands; and white, dark gray, and multicolored silts and clays; thickness 0 to 800 feet. Includes Raritan and Patapsco Formations - Gray, brown, and red variegated silts and clays; lenticular, cross-bedded, argillaceous, subrounded sands; minor gravels; thickness 0 to 400 feet; Arundel Clay - Dark gray and maroon lignitic clays; abundant siderite concretions; present only in Baltimore-Washington area; thickness 0 to 100 feet; and Patuxent Formation - White or light gray to orange-brown, moderately sorted, cross-bedded, argillaceous, angular sands and subrounded quartz gravels; silts and clays subordinate, predominantly pale gray; thickness 0 to 250 feet.
StateMaryland
NamePotomac Group, including Raritan and Patapsco Formations, Arundel Clay, and Patuxent Formation
Geologic ageCretaceous
Original map labelKp
Primary rock typegravel
Secondary rock typesand
Other rock typessilt; clay or mud
Lithologic constituents
Major
Unconsolidated > Coarse-detrital > Sand
Minor
Unconsolidated > Fine-detrital > Clay
Unconsolidated > Fine-detrital > Silt
Unconsolidated > Coarse-detrital > Gravel
Map references
Cleaves, E.T., Edwards, J., Jr., Glaser, J.D., 1968, Geologic Map of Maryland: Maryland Geological Survey, Baltimore, Maryland, scale 1:250,000.
Unit references
Cleaves, E.T., Edwards, J., Jr., Glaser, J.D., 1968, Geologic Map of Maryland: Maryland Geological Survey, Baltimore, Maryland, scale 1:250,000.
Unpublished digital version of the Maryland state geologic map that was digitized by the USGS Water Resources Office in Towson, MD
Geographic coverageAnne Arundel - Baltimore - Cecil - Charles - Harford - Howard - Kent - Montgomery - Prince George's - Baltimore

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