Gros Ventre landslide

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The Gros Ventre landslide (pronounced GROW-VAUNT), is located in the Gros Ventre Wilderness of Bridger-Teton National Forest, Wyoming, United States. The Gros Ventre landslide is 7 miles (10 km) east of Jackson Hole valley and Grand Teton National Park. It is believed that the landslide occurred on June 23, 1925, after several weeks of heavy rain. The landslide created a huge dam across the Gros Ventre River, backing up the water and forming Lower Slide Lake. Approximately 50 million cubic yards (38,000,000 m³) of primarily sedimentary rock slid down the north face of Sheep Mountain, crossed over the Gros Ventre river and raced up the opposing mountainside a distance of 300 feet (100 m). The landslide created a huge dam over 200 feet (60 m) high and 400 yards (400 m) wide across the Gros Ventre River, backing up the water and forming Lower Slide Lake. On May 18, 1927, a portion of the landslide dam failed, resulting in a massive flood that was 6 feet (2 m) deep for at least 25 miles (40 km) downstream. The small town of Kelly, six miles (10 km) downstream, was wiped out killing 6 people. It is one of the world's largest known examples of recent mass wasting events aside from volcanic eruptions. Slide Lake is now much smaller than before the flood but is considered an outstanding location for boating and fishing.

Today, the landslide is partially reclaimed by the surrounding forest but is still an obvious landmark from many vantage points in the Jackson Hole valley. It is easily accessible by traveling north from Jackson, Wyoming or south from Moran, Wyoming and then taking the Antelope Flats road east off of route 26.