A volcanic cone composed of volcanic ejecta and basalt flows is located in the southwest quarter of T. 45 N., R. 108 W., Park County. The base of the cone is at an elevation of 10,800 feet, and rests upon the Oligocene Wiggins Formation. Whole-rock analysis of the flow gave a K-Ar age of 3.6 (+ or -1.0) m.y. or latest Pliocene. A geologic sketch map and cross sections are included. Analyses are tabulated.