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Introduction_______________________________ 1 Previous investigations______________________ 1 Present investigation and methodology ____________ 2 Acknowledgments _________________________ 3 Geology__________________________________ 3 Landslide problem___________________________ 6 Landslide types _____________________________ 6 Soil creep______________________________ 7 Slumps and earthflows ______________________ 9 Debris slides, debris flows, and debris avalanches ______ 11 Rockfalls ________________________________________ _____________ 13 Other types ____________________________ 15 Geologic and other factors that affect slope stability_______ 15 Natural factors __________________________ 16 Parent material characteristics______________ 16 Soil cover ___________________________ 20 Physical properties of rocks and soils___________ 20 Slope steepness and configuration _____________ 22 Precipitation _________________________ 22 Presence of old landslides __________________ 23 Oversteepening of slopes by stream erosion _______ 24 Manmade factors _________________________ 24 Overloading slopes______________________ 24 Excavation at the base of slopes______________ 24 Alteration of drainage conditions _____________ 24 Vegetation removal _____________________ 24

William Morris Davis (1888) considered the Appalachians to have had an important role in the development of geomorphology. He saw the systematic study of topography as largely of American origin, and suggested that there were two steps in its development. The first began about 1840 with the founding of the Eastern state surveys, during which geologists such as Lesley (1856) established the intimate relationship between topography and structure (in the broad sense) in the Appalachians. During this first step, according to Davis, topographic form was regarded as acompleted product of extinct processes. Topography revealed structure, but it did not then reveal the long history that the structure has passed through. … The systematic relation of forms to structure, base level, and time; the change of drainage areas by contest of headwaters at divides; the revival of exhausted rivers by massive elevations of their drainage areas; all these consequences of slow adjustments were then unperceived (Davis, 1888, p. 14). The awareness of such principles, the second step in the advancement of the study of topography, came about largely as a result of the geological exploration of the western U.S., exemplified by the work of Powell (1875, 1876) and Gilbert (1877). Once this awareness came about, however, these principles were applied to the Appalachians; Davis (1888, p. 15) stressed the importance of the Appalachians in this second phase as well as the first: If it be true that the greater part of this second advance is American like the

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