Dakota Sandstone and lower Mancos Shale stratigraphy at the Red Wash measured section and nearby wells in the Four Corners platform, Navajo Reservation, San Juan County, New Mexico

Abstract

The Dakota Sandstone of the Four Corners Platform consists of a thick White Rock Mesa Member with thin westward edges of the Whitewater Arroyo Shale and Twowells Sandstone Members, overlain by the complete Graneros Shale and Greenhorn Limestone Members of the Mancos Shale. A key outcrop is at Red Wash on US highway 64 west of Shiprock, NM. Paleocurrent interpretations of fluvial crossbedding indicate an ENE transport direction. Logs of 100 wells in the nearby subsurface provide details that show thinning of the lower fluvial section and thickening of the upper marine section to the east.