The Slumgullion Earthflow in the

San Juan Mountains The San Juan Mountains is a high and rugged mountain range in the Rocky Mountains in southwestern Colorado and northwestern New Mexico. The area is highly mineralized (the Colorado Mineral Belt) and figured in the gold and silver mining industry ...

in Hinsdale County,

Colorado Colorado (, other variants) is a state in the Mountain states, Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the wes ...

has been a

National Natural Landmark The National Natural Landmarks (NNL) Program recognizes and encourages the conservation of outstanding examples of the natural history of the United States. It is the only national natural areas program that identifies and recognizes the best ...

since 1983. It is also a Colorado Natural Area and an

Area of Critical Environmental Concern Areas of Critical Environmental Concern (ACEC) is a conservation ecology program in the Western United States, managed by the Bureau of Land Management (BLM). The ACEC program was conceived in the 1976 Federal Lands Policy and Management Act (F ...

. The

earthflow An earthflow (earth flow) is a downslope viscous flow of fine-grained materials that have been saturated with water and moves under the pull of gravity. It is an intermediate type of mass wasting that is between downhill creep and mudflow. The ...

, a slow-moving landslide, crawled down the valley about 700 years ago creating the long and wide mass. The earthflow lies a few miles south east of Lake City. The landmark site covers and is owned by the

US Forest Service The United States Forest Service (USFS) is an agency of the U.S. Department of Agriculture that administers the nation's 154 national forests and 20 national grasslands. The Forest Service manages of land. Major divisions of the agency inc ...

and the Bureau of Land Management. It is "a striking example of mass wasting (the movement of large masses of earth material)." The Lake Fork of the Gunnison River was dammed by the earthflow, creating Lake San Cristobal. A second earthflow has been moving continuously for about 300 years over older stable rock. It moves at a rate of about 7 meters (23 feet) per year. The area is a habitat for elk and deer. It is crossed by Colorado Highway 149, the principal highway of the area connecting

Lake City, Colorado Lake City is a Statutory Town that is the county seat, the most populous community, and the only incorporated municipality in Hinsdale County, Colorado, United States. It is located in the San Juan Mountains in a valley formed by the convergenc ...

with Creede.

References

{{authority control Landforms of Hinsdale County, Colorado San Juan Mountains (Colorado) National Natural Landmarks in Colorado Protected areas of Hinsdale County, Colorado Geology of Colorado