The Powderhorn Wilderness is a wilderness area in Hinsdale and Gunnison counties, Colorado, United States, located northeast of Lake City.
Description
Most of the northern part of the wilderness area, , about 77.5%, is located on Bureau of Land Management land and its southern portion, , about 22.5%, is located within the Gunnison National Forest. Elevations in the wilderness range from at the West Fork Powderhorn Creek to at the summit of Calf Creek Plateau.
The Powderhorn Wilderness is an important watershed for the Gunnison River. The area protects the East, Middle, and West forks of Powderhorn Creek, which flow into Cebolla Creek and then the Gunnison River. Calf Creek, which is on National Forest land, flows south and eventually joins Cebolla Creek. Within the wilderness area there are numerous small lakes and beaver ponds. The largest of these are Devil's Lake and Powderhorn Lake.
Much of the area sits above timberline at and it is recognized as one of the largest expanses of tundra in the contiguous United States.
Geology
thumb|left|Basaltic rock of the Hinsdale Formation. Devils Lake, the largest lake in the Powderhorn Wilderness, is in the distance.
The Powderhorn Wilderness is within the San Juan volcanic field and volcanic rocks dominate the region. The central, highest terrain of the wilderness is composed of basaltic lava flows of the Hinsdale Formation, which are dated at 16 to 19 million years old. These lava flows are thought to be among the last volcanic events in the area and are some of the best preserved. The Hinsdale Formation lava flows form an expansive alpine highland where the two highest ridges are Calf Creek Plateau and Cannibal Plateau.
Underlying these basalt flows are sheets of older volcanic rocks that are exposed around the periphery of the wilderness. From youngest to oldest, these rocks include Cochetopa Park Tuff, Nelson Mountain Tuff, Carpenter Ridge Tuff, and Fish Canyon Tuff. The volcanic ash that formed these tuffs came from Oligocene eruptions within the San Juan volcanic field. These eruption sites are the Cochetopa Caldera, San Luis Caldera, Bachelor Caldera, and La Garita Caldera, respectively. On the northern and western reaches of the wilderness there are yet older volcanic rocks exposed. These Oligocene lavas and breccias have been dated at 32 million years old.
The most popular destination in the wilderness is Powderhorn Lakes. These two lakes are nestled in a beautiful glacial cirque, and the trip one-way is well worth the effort. Start at the Powderhorn Lake Trailhead and take the well-maintained Powderhorn Lakes Trail south to the lakes. The upper lake is at an elevation of (). Given the popularity of this trail, those seeking remoteness and more solitude may find other trails and destinations more rewarding.