1. The difference between the potentiometric surfaces of the Magothy aquifer of September 1975 and September 1981 in southern Maryland [cartographic material] Yale Public content 1982. 2023-04-19T19:58:23Z. 2023-04-21T21:35:14Z. Mack, Frederick K. U.S. Geological Survey. English. cartographic image. Public. Maryland, Annapolis Region, and Annapolis Region.