The Night the Mountain Fell is a riveting account of the deadly 7.5 earthquake that struck Hebgen Lake in Yellowstone Park, Montana, on August 1959. Also known as the Yellowstone Earthquake, the disaster caused massive flooding and the worst landslide in the history of the Northwestern United States. In The Night the Mountain Fell author Edmund Christopherson gives us a page-turning, journalistic-style account of how the deadliest earthquake in MontanaÕs history ultimately claimed the lives of twenty-eight people.