Base source: USGS 1:100,000 county base dated 1977; interpretations derived from soil map constructed 1967.; "Projection and 10,000-meter grid ticks, zone 18: Universal Transverse Mercator. 25,000-foot grid ticks based on Maryland coordinate system."; June 1980.; Includes location map. 66 x 51 centimeters Scale 1:100,000; 1 cm. = 1 kilometer