Base source: USGS county base dated 1976; interpretations derived from soil map constructed 1961.; "Projection and 10,000-meter grid ticks, zone 18: Universal Transverse Mercator. 25,000-foot grid ticks based on Maryland coordinate system."; Nov. 1979.; Includes location map. 57 x 66 centimeters Scale 1:100,000; 1 cm. = 1 kilometer