http://pec.lib.wvu.edu/record/P11861929Marine faunas of the Devonian tree horizons of Tygart Valley, West Virginia.Journal article reprint from: <em>American Journal of Science,</em> v.17 (1929:Apr.). Tilton, John Littlefield, b. 1863.Geology, Stratigraphic--Devonian.Geology--West Virginia--Tygart Valley.14256