"Géologie Virginie (États-Unis) Guides." . . "Géomorphologie Virginie (États-Unis)" . . . . . "Geomorphology, vegetation, and Patowmack Canal construction problems, Great Falls Park, Potomac River, Virginia : Potomac River Gorge, Virginia, July 13, 1989"@en . "Geomorphology, Vegetation, and Patowmack Canal Construction Problems: Great Falls Park, Potomac River, Virginia: Potomac River Gorge, Virginia, July 13, 1989" . . "Electronic books" . "Guidebooks" . "Guidebooks"@en . . . . . . . . "Geomorphology, vegetation, and Patowmack Canal construction problems, Great Falls Park, Potomac River, Virginia Potomac River Gorge, Virginia, July 13, 1989" . . . . . . . . . . . . "Geomorphology, Vegetation, and Patowmack Canal Construction Problems Great Falls Park, Potomac River, Virginia: Potomac River Gorge, Virginia, July 13, 1989"@en . . . . . "Congrès géologique international (28 : 1989 : Washington, D.C.)" . . . "International Geological Congress (28th : 1989 : Washington, D.C.)" . . . . . "Sciences naturelles Virginie (États-Unis)" . .