A look at the placid Leather Pool, on Yellowstone's Fountain Paint Pot Trail. The pool "underwent dramatic changes after the Hebgen Lake Earthquake of 1959," reads a National Park Service brochure. "Prior to the earthquake, it was a warm (143 degrees Fahrenheit) pool that supported leather-like thermophilic brown bacteria. After the earthquake, water temperatures rose to boiling and killed the microorganisms. Since that time, Leather Pool has cooled and again supports the brown bacteria."