|Lower Potomac Group, Eastern Coastal Plain of Maryland, Delaware, and New Jersey
Hansen (1984) and Trapp and others (1984) provided discussions of pressure gradients for the lower Potomac Group (Waste Gate Formation) of eastern Maryland. They found that observed pressures generally follow a normal lithostatic pressure gradient of 0.45 psi/ft. To derive a pressure distribution map for the GIS, we took the 0.45 psi/ft and multiplied the depth to the top of the lower Potomac aquifer (c12bpotomac).
Hansen, H. J., 1984, Hydrogeologic characteristics of the Waste Gate Formation, a new subsurface unit of the Potomac Group underlying the eastern Delmarva Peninsula: Maryland Geological Survey Information Circular 39, 22 p.
Trapp, H., Jr., and Meisler, H., 1992, The regional aquifer underlying the northern Atlantic coastal plain in parts of North Carolina, Virginia, Maryland, Delaware, New Jersey, and New York-summary: U.S. Geological Survey, Professional Paper 1404A, 33 p., 11 plates.