Slumgullion Earthflow
The Slumgullion Earthflow in the San Juan Mountains in Hinsdale County, Colorado has been a National Natural Landmark since 1983. It is also a Colorado Natural Area and an Area of Critical Environmental Concern.
The earthflow, 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 and the Bureau of Land Management. It is "a striking example of mass wasting." 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 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 with Creede.
