In early October 2015, a hunter was out walking the foothills of the Bighorn Mountains in northern Wyoming.  He discovered a small crack in the countryside.  A few weeks later, when someone else had a chance to check it out, it had grown to nearly a half a mile long (2250 feet) and 150 feet wide.  Geologists from the Wyoming State Geologic Survey attribute it to a landslide  caused by groundwater erosion.  CBS News has more information.