Crested Butte
Crested Butte is a prominent mountain summit in the Elk Mountains range of the Rocky Mountains of North America. The peak is in Gunnison National Forest, northeast by east (bearing 59°) of the Town of Crested Butte in Gunnison County, Colorado, United States. Ski lifts and runs of the Crested Butte Mountain Resort occupy the north side of the mountain. Climate. The Köppen Climate Classification subtype for Crested Butte is "Dfc" which is continental subarctic. This climate type is dominated by the winter season with a long, bitterly cold period of minimal daylight hours, heavy snowfall and  low humidity. The annual snowfall average is with January recording the highest average snowfall at . July is the warmest month with an average temperature of while January is the coldest month with an average temperature of . The average temperature for the year is . Geology. Crested Butte is a laccolith, formed when magma intruded into Mancos Shale approximately 30 million years ago. Subsequently the softer, overlying sedimentary rock has eroded away, exposing the more resistant igneous rock. The bulk of Crested Butte is composed of quartz monzonite porphyry and granodiorite porphyry. The lower slopes consist of Mancos Shale overlain with debris  from the granitic slopes above. The Mancos Shale at the base of Crested Butte can be an unstable substrate for building and result in geologic hazards such as landslides and earthflows. Crested Butte is one of over a dozen laccoliths in the Elk and adjacent West Elk Mountains. The magma intrusions associated with these laccoliths resulted in contact metamorphism of the surrounding sedimentary rock and mineralization. The metamorphism also altered the bituminous coal present in the sedimentary rock into a higher quality coal, including anthracite, which was mined extensively in the Crested Butte area during the late 19th and early  20th centuries.