The term “landslide” is broadly defined as any “downward and outward movement of slope-forming materials composed of natural rock, soils, artificial fills, or combinations of these materials. The moving mass may proceed by any one of three principal types of movement: falling, sliding, or flossing, or by their combinations” (Varnes, 1958). Landslides and areas of potential landslides are fairly common in the rugged terrain of the Salina quadrangle. In much of the western half of the map area, relatively high rainfall, steep slopes, and flat layers of hard rock on top of very soft incompetent rock all favor landsliding, chiefly as slides and earth flows. In arid parts of the quadrangle, principally in the east half, alternating flat layers of hard and soft rocks are eroded to bare cliffs separated by benches, and rockfalls are the dominant type of landsliding. Landslides were more active in the wetter climate of the Pleistocene Epoch, which ended several thousand years ago (Smith and others, 1963, p. 52). Although landslide deposits are abundant in the Salina quadrangle, few landslide movements have been documented during historic time, partly because landslides are generally less active now than during Pleistocene times, partly because movement is commonly very slow and thus escapes notice, and partly because of the remoteness and sparse population of the area.
