Lower part of the marine Cretaceous at Gold Creek, Vermejo Park, New Mexico
— Charles L. Pillmore and D. L. Eichler

An unusually clean exposure of Upper Cretaceous marine rocks, including the Graneros, Greenhorn and Carlile formations, and the Fort Hays and Smoky Hill Members of the Niobrara Formation occurs at Gold Creek on the east flank of the Sangre de Cristo Mountains in extreme northern New Mexico. Throughout most of this area, the ridge-forming Dakota Sandstone is commonly vertical or overturned, and the marine shale part of the sedimentary section is usually covered by debris from the Dakota. In areas to the north, where the Dakota dips eastward into the Raton Basin, the nonresistant marine shales, marls and limestones form slopes that are generally covered by soil and colluvium.

 

The excellent exposure of Upper Cretaceous rocks at Gold Creek is the apparent result of a combination of landsliding and erosion that occurred on the north side of the creek, immediately east of the point where the creek cuts through The Wall—a steep, rugged hogback formed by resistant rocks of the Dakota Sandstone. We measured a stratigraphic section at this location on July 20, 1966, and collected samples for microfossils. We were assisted by P. J. Varney, U.S. Geological Survey, and C. Porter, University of Colorado. In the laboratory, Michael Evetts analyzed the foraminifera from the upper black shale unit of the Carlile Formation.