Crystalline rocks of the Potomac River Gorge near Washington, D.C Reed, John Calvin Jr 1930- creator author. Jolly, Janice L. W. author. Geological Survey (U.S.) issuing body. text bibliography dcu 1963 monographic eng remote 1 online resource (iii, H16 pages) : illustrations, maps + 2 plates. by John C. Reed, Jr., and Janice Jolly. Title from title screen (viewed September 24, 2014). "A description of the rocks exposed in the gorge of the Potomac River below Great Falls, with a discussion of their structural and metamorphic history." Includes bibliographical references (page H16). n-us-dc Crystalline rocks Washington Metropolitan Area Crystalline rocks Potomac River Valley Geology Washington Metropolitan Area Geology Potomac River Valley Geology, Stratigraphic Paleozoic Crystalline rocks Geology Geology, Stratigraphic Paleozoic Geologic Period Washington (D.C.) From 230 to 570 million years ago fast I 19.16:414-H I 19.16:414-H Crystalline rocks of the Potomac River Gorge near Washington, D.C Reed, John Calvin, Jr., 1930-. (OCoLC)2724977 Geological Survey professional paper ; 414-H Contributions to general geology http://purl.fdlp.gov/GPO/gpo83607 http://purl.fdlp.gov/GPO/gpo833607 COP 140929 20180214131950.0 in00003889354 eng