Segment of the southern Rocky Mountains, southwestern Colorado and northern New Mexico, U.S. The mountains extend from southwestern Colorado along the course of the Rio Grande to the Chama River in northern New Mexico. Many peaks in the northern section exceed 14,000 ft (4,300 m), including Mounts Eolus, Sneffels, and Redcloud. Uncompahgre Peak is the highest, at 14,309 ft (4,361 m). Composed mainly of volcanic rocks, the mountains have a rugged, well-forested terrain.