Oh My Rockslide!

On June 16, 2014, we stopped in the small town of Kelly, WY to study the mass wasting catastrophe that took place in 1925. Stepping off the bus and seeing the hundred-foot deep scar was shocking. The unexpected, fast-moving landslide is known as the Gros Ventre Rockslide. In a matter of minutes, rock and debris came tumbling down the mountains, depositing 50 million cubic yards of rock and soil. The large amount of debris blocked the Gros Ventre River and created a 200-foot dam, producing Lower Slide Lake.

The goal of this stop was to study why this unexpected landslide occurred. We used our background knowledge of geology and our intelligent professors to piece together why this slide happened. The bedrock is tilted and the slopes were oversteepened due to erosion from the Gros Ventre River. Small earthquakes, gravity, and rainfall mixed together, creating a recipe for disaster.  Also, the composition of rock has a major impact. The Tensleep Formation became slippery, enabling the slope to fail. Unfortunately, the bedrock was saturated with water, causing the ground to become unstable. Luckily only 6 citizens of Wyoming died.

After we were done piecing together the geologic history, we were able to frolic among the rock pile and got to hammer on some travertine limestone and sandstone with large quartz crystals.  Being out in the field made me feel like a real geologist!