Generalized geologic map of the crystalline rocks in central Maryland, southern Pennsylvania, and Delaware

This digital image was produced in the Summer of 2012 by the Maryland State Archives (MSA) from the original map held by the Maryland Geological Survey (MGS). We are indebted to the staff of the MGS and MSA for helping us make this these images available.This map is Plate 3 from Fisher, G.W., “Geological Interpretations of Aeromagnetic Maps of the Crystalline Rocks in the Appalachians, Northern Virginia to New Jersey”. Baltimore: Maryland Geological Survey, 1979 (Report of Investigations No. 32)