DENDROGEOMORPHIC ASSESSMENT OF THE OURAY, COLORADO AMPHITHEATER LANDSLIDE

A dendrogeomorphic assessment of the steep slopes surrounding a United States Department of Agriculture (USDA) Forest Service campground in the Ouray, Colorado Amphitheater, is needed for a hazard assessment to mitigate damages to human life and property. The campground is situated in a glacial carved valley of the San Juan Mountains. Rockfalls from a nearby bedrock escarpment pose a significant hazard to the campgrounds seasonal operations and partisans safety. This study aims to (i) reconstruct, using modern dendrogeomorphic techniques, a rockfall chronology, (ii) evaluate the spatial-temporal distribution of rockfall, and (iii) to address the historical influence of meteorological variables on the Northeastern slopes of the high alpine campground. Rockfall related tree disturbances are visible in the form of impact scars, curved or leaning trees, and observation of areas absent of older vegetation due to large mass-wasting events. The sampling of trees with the use of an increment coring device allow for microscopic analysis of reaction wood, suppression and release events, and cellular scaring that provide evidence for the assumptions. This assessment will generate a model of the surficial slope instability conditions to be presented to the County of Ouray so that the conditions of rockfall mechanics can be better understood and mitigation processes may be emplaced.