Slumgullion Earthflow

The 4-mile long landslide is much less threatening than it initially appears. That is because it is a slow-moving earthflow, meaning it only moves approximately 20-feet per year. It was initially created over 700 years ago when a volcanic caldera broke and cascaded down the mountainous slopes. The flow was eventually dammed by the Gunnison River which has slowed the speed of the landslide. This fascinating geological phenomenon has been intensively studied, and geologists have discovered that the rate of the slide depends on the season, tidal forces, and air pressure. It is considered a National Natural Landmark and an Area of Critical Environmental Concern by the BLM.