- GeoRef, Copyright 2004, American Geological Institute. Reference includes data from Bibliography and Index of North American Geology, U. S. Geological Survey, Reston, VA, United States
Highly contorted siltstone strata of the Satanka Formation (Permian) are exposed in a stream bank northeast of Laramie, Wyo. Overlying the Satanka at this locality are Pleistocene fluviatile sediments (several lenses of sand and a bed of cobbles) which are also involved in the convolutions. In contrast with most previously described Pleistocene convolutions, those discussed herein show a pronounced directionality. The folds are asymmetrical with their steep limbs dipping southwest and many are overturned in the same direction. Although these features may have formed under periglacial conditions, a simple freeze-thaw mechanism is insufficient to account for their configuration. Deposition of the overlying load of cobbles on an unstable slope may well have induced the deformation.