Large quaternary landslides in the central appalachian valley and ridge province near Petersburg, West Virginia |
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| Authors: | C Scott Southworth |
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| Institution: | 1. Universidade de Lisboa, FCiências.ID, Campo Grande, Edifício C1, 3° piso, 1749-016 Lisboa, Portugal;2. Universidade de Lisboa, Faculdade de Ciências, Departamento de Geologia and Instituto D. Luiz, Campo Grande, Edifício C6, 3° piso, 1749-016 Lisboa, Portugal;1. Department of Earth and Atmospheric Sciences, Indiana University, 1001 E 10th Street, Bloomington, IN 47405-1405, USA;2. Western New York Waterfall Survey, 784 Meadow Drive, North Tonawanda, NY 14120, USA;3. Indiana Geological and Water Survey, Indiana University, 611 N. Walnut Grove Avenue, Bloomington, IN 47405-2208, USA;4. Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma 2, Via V. Murata 605, 00143 Roma, Italy;5. Faculty of Environmental Science and Engineering, Babes Bolyai University, Cluj-Napoca, Romania;6. Department of Geology, University at Buffalo, 411 Cooke Hall, Buffalo, NY 14260, USA;7. California Institute of Technology, Pasadena, CA 91125, USA |
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| Abstract: | Geological mapping and photointerpretation of side-looking airborne radar images and color-infrared aerial photographs reveal two large Quaternary landslides in the Valley and Ridge province of the central Appalachians near Petersburg, W. Va. The Elkhorn Mountain rock avalanche occurs on the thrust-faulted northwestern flank of the Elkhorn Mountain anticlinorium. A minimum of 7 × 106 m3 of quartzite colluvium was transported more than 3 km from a 91 m high escarpment of Silurian Tuscarora Quartzite. The extensively vegetated deposit may owe, in part, its transport and weathering to periglacial conditions during the Pleistocene. In contrast, the Gap Mountain rock block slide is a single allochthonous block that is 1.2 km long, 0.6 km wide, and at least 60 m thick. The 43 × 106 m3 block is composed of limestone of the Helderberg Group and the Oriskany Sanstone of Early Devonian age. Planar detachment probably occurred along a dissolution bedding plane near the Shriver Chert and the Oriskany Sandstone contact. Failure probably was initiated by downcutting of the South Branch Potomac River during the Pleistocene. Landslides of this magnitude suggest accelerated erosion during periglacial climates in the Pleistocene. The recognition of these large slope failures may provide evidence of paleoclimatic conditions and, thereby, increase our understanding of the geomorphologic development of the Valley and Ridge province. |
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