Rabbit Ears Pass (el. 9426 ft, 2873 m) is a high mountain pass in the Rocky Mountains of northern Colorado in the United States, where US highway 40 crosses the Continental Divide. North of the summit is Rabbit Ears Peak which has the shape of rabbit ears, which displays two large columns of basalt rock formations from the second volcanic episode. Rabbit Ears Peak is underlain by a pink tuff and the basalt immediately to the west is underlain by red, vesicular ash. Volcanic breccia occurs only at the Peak, which is a large stratified breccia pile. The three basal layers are cut by a basalt dike immediately beneath the peak. From petrographic evidence there appears to have been one period of lava flows and this surface can be seen at Rabbit Ears Peak. The Rabbit Ears Pass area covers 56 square miles in north central Colorado at the junction of the Rabbit Ears Range and the Park Range. The Rabbit Ear Pass highway, which is one of the most important transcontinental road links in the nation, was built by the state of Colorado, Routt, Grand, and Jackson counties, and the United States Forest Service. It was started in 1911 and was not completed until 1917. Present work is along lines of reducing curves and improving the roadbed. The road connects Routt with Jackson and Grand counties and furnishes direct connection with Denver by way of Kremmling and Berthoud Pass, where the main range is crossed again. The pass straddles the Continental Divide at the southern end of the Park Range. The name is taken from nearby Rabbit Ears Peak, a mountain in the Park Range to the north that is prominently visible from the east side of the pass during good weather. The pass separates the upper basin of the Yampa River on the west from North Park and the upper basin of the North Platte River on the east. U.S. Highway 40 travels over the pass between Steamboat Springs and Kremmling; this is one of three crossings of the Continental Divide along the highway, along with nearby Muddy Pass to the southeast and the much higher Berthoud Pass closer to Denver. The climate of Rabbit Ears Pass is generally semi-arid to humid. Vegetation consists mostly of pine, spruce, and aspen trees. Sagebrush grows on the Niobrara, Pierre and Coalmount formations. Undergrowth is dense in most places. Like many