Designated as a National Natural Landmark in 1983, this relatively young and still active slide is one of the best examples of a rare geologic phenomenon known as “mass wasting” in the world. Centuries ago, a portion of the Lake City caldera broke off of Mesa Seco and started moving down the steep slopes of the Lake Branch of the Gunnison River. Unlike many other slides, this was a slow-moving mass of materials known as mass flow or earth flow. The flow is about four miles long. Around 700 years…
