UPLAND PERIGLACIAL FEATURES AND BARE BEDROCK EROSION RATES INFERRED FROM 10BE, DOLLY SODS, WEST VIRGINIA

The form of many high elevation plateaus in the central Appalachians has been hypothesized to reflect the dominance of paleoperiglacial processes in shaping these uplands. Evidence cited to support this hypothesis includes summit flats that truncate structure, summit tors, cyroplanation terraces, boulders streams, and sorted patterned ground (e.g., Clark and Hedges, 1992). Braun (1989) proposed periglacial processes may rapidly erode these uplands at rates of ~100-300 m/Ma. If true, this implies periglaciation is the dominant process shaping these uplands. We attempt to evaluate the efficacy of periglacial processes in the Dolly Sods area, West Virginia, through measurement of the cosmogenic radionuclide 10Be and analysis of periglacial features. 10Be analyses are pending on samples collected from bare bedrock surfaces, including tors. The results will provide erosion rates averaged over ~10 ka to ~100 ka, and should therefore span the most recent glacial maximum. In the field, we found summit and side slope topography to be strongly dependent on structure and lithology. Features previously interpreted as cryoplanation terraces do not truncate lithology, and are localized along less-resistant, thinly bedded siltstones, while terrace risers are formed in more resistant, massive sandstone units. Summits and gentle side slopes on the broad upland dip at angles comparable to the underlying sandstone unit. Mapping and orientation analyses of fabric indicate that not all boulder streams are necessarily of periglacial origin. Our analysis suggests many of these landforms may be attributed to origins that are not necessarily periglacial.