Landslides are unfortunately a common problem around the globe, especially in areas of growth where humans alter the landscape. But landslides can happen even when there isn't human activity to artificially steepen slopes or reduce the cohesiveness of the land surface. One such landslide was the Thistle Landslide, that ended up destroying the town of Thistle, Utah.
The picture above is overlooking the landslide itself, which came down the valley in the center of the picture. The landslide filled the Spanish Fork River valley, which is located down below the train tracks as seen here. Fall of 1982 and winter/spring of 1983 had been extra wet, and a late snowfall in April along with a quick thaw caused 15 million cubic meters of earth to start sliding down the slope. The valley was populated with eroded debris from the North Horn and Ankareh Formations (a mixture of shales, silstones, and sandstones) that were nestled in a "trough-shaped depression", AKA a paleovalley.
|View of Thistle Lake after the landslide. Image from the USGS.