Loessial Deposits and Soils of the Snake and Tributary River Valleys of Wyoming and Eastern Idaho

Abstract

AbstractLoess mantles hilly uplands along rivers in Star Valley and Jackson Hole in western Wyoming and Teton County in eastern Idaho. Mineralogy of the loess is relatively uniform from pedon to pedon and its particle size is relatively uniform with depth. Thickness and particle size of the loess relative to distance from the Salt River in Star Valley show that the local flood plain was its probable source. In Jackson Hole, although the mineralogy of the loess is similiar to that in Idaho, its particle size suggests that it was carried by periglacial winds which came down over outwash plains and alluvium in the north and moved south through the valley. The refractive index of glass shards in the loess is < 1.505 suggesting that the shards are from Glacier Peak, thus adding support to a late Wisconsin Age for the loess.