Geology of Wind River Mountains, Wyoming

Abstract

The Wind River Mountains are made up of a core of pre-Cambrian granodiorites, except at the south end where schists predominate. On the northeast flank the dips of the sediments range from 10° to 15°. The dipping sediments range from Cambrian to late Cretaceous in age, only the Silurian being absent. Eocene, Oligocene, Pliocene, and Pleistocene overlap the older formations in some places. On the east side a series of anticlines parallels the main range about 25 miles from the summit. Minor faults affect the anticlines as well as the main range on the east side and the pattern of the lakes indicates much faulting in the pre-Cambrian core. The main uplift and folding of the range came at the close of the Mesozoic, but minor uplifts occurred during the Cenozoic. That the uplifts were irregular is indicated by the absence of Ordovician and Devonian strata at the south end, and the pinching-out, north of the range, of the Tensleep, Phosphoria, and Chugwater formations. The Lander sandstone at the base of the Ordovician in the southern end of the Wind River Mountains is absent at the northern end and thickens to 80 feet or more on the east side of the Big Horn Mountains. The glaciation and peneplanation of the range are worthy of more discussion than can be given in a short paper, and the development of the drainage lines east of the range should be treated at length. The known oil-bearing formations on the east flank are Madison, Tensleep, Phosphoria, Dinwoody, Sundance, Dakota, Mowry, and Frontier.