EARTHWORKS AS A PROXY FOR NATURAL HILLSLOPE DEGRADATION

Human constructed earthworks such as Civil War earthen fortifications in Charleston, SC can serve as proxies for natural landscapes and for delineating changes in morphology as a landscape degrades with time. Evolution of natural hillslopes is difficult to quantify due to the very slow rates of change and the impossibility of knowing the exact initial morphology of the hillslope. Results from studies conducted on the Charleston fortifications have provided much insight toward understanding slope degradation. Observed morphologic changes include: 1) decreased mid-slope angle, 2) increased rounding (decreased curvature) at slope base and crest, 3) small scale morphologic features have become more subdued.

Comparison of detailed surveys of extant slope profiles with original engineering plans documents changes in cross-section profile and establishes trends/patterns of slope degradation. This approach is similar to the weathering rate studies based on observation of the degradation of lettering on tombstones of various rock types.