1. Physiographic geology sheet, Md.-D.C.-Va., Washington quadrangle (central portion) [cartographic material] Yale Public content 1901. 2003-07-16T14:52:28Z. 2015-10-27T22:20:38Z. Darton, Nelson Horatio, 1865-1948. U.S. Geological Survey. English. Public. Washington (D.C.) and Washington Metropolitan Area.