Rabbit Ears Pass is a high mountain pass in the Rocky Mountains of northern Colorado in the United States, where U.S. Route 40 crosses the Park Range (Colorado). 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.