THE USE OF DENDROCHRONOLOGICAL ASSESSMENT IN DATING A GEOLOGIC SLUMP EVENT IN ERIE BLUFFS STATE PARK, ERIE, PA

Tree rings provide a means for dating various geologic phenomena and, specifically, have been used to date mass wasting events (Bryant et al., 1989; Harker, 1996; Alestalo, 1971). Here we use tree rings to determine the timing of an individual slump block along the Lake Erie shoreline in Erie Bluffs State Park in Erie, PA with the ultimate goal of calculating the rate of shoreline erosion along this section of the lake. In particular, this project investigates the relationship between tree-ring width patterns and hill slope failure. The process of such an investigation involves sampling and analyzing cores from trees that appear to pre-date and post-date the slumping event at a specific bluff location. By comparing the ages of trees that grew before and after the slumping event, it should be possible to date the slump block. Our sampling is currently in progress, but preliminary core samples from a tree pre-dating the slump exhibit ring width variance. Since width variance is present in these cores, we know it will be possible to identify the timing and geomorphologic nature of the slumping event. We are continuing to take core samples along transects parallel and perpendicular to the slump block. This project is the first known attempt at using dendrochronology to date hill slope failure in Erie Bluffs State Park. If preliminary dating results can be verified by subsequent samples, dates may be used to calculate the erosion rate of the bluffs at the location under investigation and demonstrate that this technique could be applied to other locations along the Lake Erie bluffs.