1. Map showing how the potentiometric surface of the Magothy aquifer of August, 1980 differed from the potentiometric surface of September 1977, in southern Maryland [cartographic material] Yale Public content 1981. 2023-02-10T22:34:18Z. 2023-02-14T23:01:58Z. Geological Survey (U.S.). The Survey. English. cartographic image. Public. Maryland and Maryland.