Laserfiche WebLink
<br />W shale and sandstone is significantly greater than the mean soil depth <br />~ for basins underlain by shale. The explanation for this is probably the . <br />~ lower erodibility of sandy soils, their greater infiltration rates and <br />better vegetative cover (Lusby et aI, 1963). <br />Hadley 'and Lusby (1967) emphasize the importance of hillslopeaspect <br />on soil depth and hillslope erosion. That is, since the north-facing <br />slopes are colder and retain more moisture, they are expected to have <br />deeper soil development and shorter, steeper slopes than the south- <br />facing slopes. However, Johnson's (1982) field observations suggest <br />that aspect plays a relatively minor role in the geomorphic processes of <br />the area. <br /> <br />Geomorphic Stability <br /> <br />Generally, the badlands are areas of rapid erosion. Where rills and <br />channels are steep, they are efficient conduits for runoff and sediment <br />transport. Many badland basins are undergoing active erosion due to the <br />combined effects of rill development, soil creep, and bank failure. <br />However, sediment yields can be highly variable depending on drainage <br />basin morphology and the potential for storage of sediment within the <br />drainage basins. Certainly large areas that have been classified on <br />badlands may produce relatively small amounts of sediment. In relative <br />terms, badlands underlain by interbedded shale and sandstone bedrock are <br />more stable than those underlain by shale bedrock. The former are less <br />erodible because they have a more permeable soil layer which gives rise <br />to deeper soils and greater, though minimal, vegetative cover than the <br />latter. <br /> <br />Pediments <br /> <br />Johnson's (1982) study area includes many smooth, gently sloping, <br />gravel-capped landforms that rise above the badlands. These features <br />are common along other portions of the Book Cliffs as well as in other <br />areas where Mancos Shale crops out below resistant cliffs. These <br />landforms are pediment remnants. By definition, a pediment is a gently <br />inclined planate erosion surface carved in bedrock and generally <br />veneered with fluvial gravels (American Geological Institute, 1976). <br /> <br />48 <br />