PRELIMINARY STUDY OF MASS WASTING OCCURRENCES ALONG THE MIDDLE SALUDA RIVER, JONES GAP STATE PARK AREA, GREENVILLE COUNTY, SOUTH CAROLINA
Tree cores were measured from the 1976 debris flow to determine a lag time between event and vegetation repopulation. Cores observed from the older trees in the channel were as old as 26 years, leaving a 7 year lag time. Small, deciduous trees in the 2006 channel provide a 3.5-year lag time, which is close to the lag time provided by tree coring.
Pre-1976 mass wasting events were identified by ground observations and contour features visible on 1:24,000 scale topographic maps. Overlapping aprons of mass-wasted debris line the lower parts of the north- and south-facing slopes of the Middle Saluda River valley. Upper slopes are steeper and are typified by balds of exposed Table Rock gneiss. Data from the 1976 event indicate slopes above the balds are potential source areas for future mass wasting.
Using observations from recent, well characterized events, we defined a ranking system, which ranks how likely a site may be a historical mass wasting event based on factors such as boulder accumulation, debris accumulation, rock scarring, channel shape, and the occurrence of springs/streams and joints.