Chesapeake Group; Calvert Formation (MDTc;5)

Chesapeake Group; Calvert Formation - Plum Point Marls Member: Interbedded dark green to dark bluish-gray, fine-grained argillaceous sand and sandy clay; contains prominent shell beds and locally silica-cemented sandstones; and Fairhaven Member: Greenish-blue diatomaceous clay, weathers to pale gray; pale brown to white, fine-grained argillaceous sand; and greenish-blue sandy clay; total thickness 0 to 150 feet.

State	Maryland
Name	Chesapeake Group; Calvert Formation
Geologic age	Miocene
Original map label	Tc
Primary rock type	sand
Secondary rock type	clay or mud
Other rock types	sandstone
Lithologic constituents	Major Unconsolidated > Coarse-detrital > Sand Unconsolidated > Fine-detrital > Clay Incidental Sedimentary > Clastic > Sandstone
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 Unpublished digital version of the Maryland state geologic map that was digitized by the USGS Water Resources Office in Towson, MD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 coverage	Anne Arundel - Calvert - Caroline - Charles - Kent - Prince George's - Queen Anne's - Saint Mary's - Talbot