Crested Butte is a 12,168-foot peak in Colorado’s Elk Mountains, overlooking the town of the same name and forming a prominent part of its recreation economy through the ski resort on its northern slopes. Geologically, it is not a true butte but a laccolith formed about 30 million years ago when magma intruded into Mancos Shale, leaving a hard igneous core exposed after softer layers eroded away. The same intrusions that created Crested Butte and nearby peaks also improved local coal deposits, helping drive regional mining in the late 19th and early 20th centuries. Its unstable shale contributes to landslides, and its subarctic climate brings long, snowy, bitterly cold winters.