Geology of the Cooper Ridge NE Quadrangle, Sweetwater County, Wyoming

The Cooper Ridge NE 7?-minute quadrangle is 18 miles southeast of Rock Springs, Wyo., on the east flank of the Rock Springs uplift. Upper Cretaceous rocks composing the Rock Springs Formation, Ericson Sandstone, Almond Formation, Lewis Shale, Fox Hills Sandstone, and Lance Formation, Paleocene rocks composing the Fort Union Formation, and Eocene rocks composing the Wasatch Formation are exposed and dip 5?-8? southeast. Outcrops are unfaulted and generally homoclinal, but a minor cross-trending fold, the Jackknife Spring anticline, plunges southeastward and interrupts the northeast strike of beds. Older rocks in the subsurface are faulted and folded, especially near the Brady oil and gas field.

Coal beds are present in the Almond, Lance, and Fort Union Formations. Coal resources are estimated to be more than 762 million short tons in 16 beds more than 2.5 feet thick, under less than 3,000 ft of overburden. Nearly 166 million tons are under less than 200 ft of overburden and are recoverable by strip mining. Unknown quantities of oil and gas are present in the Cretaceous Rock Springs, Blair, and Dakota Formations, Jurassic sandstone (Entrada Sandstone of drillers), Jurassic(?) and Triassic(?) Nugget Sandstone, Permian Park City Formation, and Pennsylvanian and Permian Weber Sandstone at the Brady field, part of which is in the southeast corner of the quadrangle, and in the Dakota Sandstone at the Prenalta Corp. Bluewater 33-32 well near the northern edge of the quadrangle. Other minerals include uranium in the Almond Formation and titanium in the Rock Springs Formation.