Wind Erosion as a Factor in Soil Formation in the Pierre‐Shale Landscape of Western South Dakota

Slopes exposed to the prevailing NW‐SE winds in the Pierreshale landscape of western South Dakota have been eroded at a slow rate when vegetation was either destroyed by fire or weakened by drought since at least the Pleistocene. Slopes protected from the prevailing winds have had negligible wind erosion except in areas where severe erosion created deflation basins. These blowout basins are limited to small interfluve areas, a few square miles in size, which probably had a thick layer of loose, sand‐size fissile‐shale fragments that winds could erode. Soils in areas with blowout basins usually are more weakly developed, have shale at shallower depth, have little or no gilgai development, and appear to be younger than soils in comparable areas without deflation basins. Thus, the soil age in these areas is less than would be predicted from the geomorphic relationships to Pleistocene terrace systems. Soils in one area with deflation basins have development comparable to soils derived from late‐Wisconsin drift.