부산대학교 도서관

Upshur, Vandergrift, Guernsey, and Library soils are found in southwestern Pennsylvania and in Ohio, West Virginia, and Kentucky. These soils have high clay contents, high COLE values, and slickensides and are landslide-prone. The movement caused by the wetting and drying of expandable clays, combined with gravitational forces, initiates the downslope soil movement and the formation of slickensides. Cavode and Wharton soils also have high clay contents but they are not landslide-prone. The clay mineralogy of the landslide-prone soils is of an expandable type, and that of the Cavode and Wharton is primarily nonexpandable. Thus the landscape instability of the landslide-prone soils is a function of high clay content, with a high proportion of the clay being of an expandable type.