It's a geological mystery and a rare spectacle of Nature at the world's first National Park.  Yellowstone National Park occupies over 2.2 million acres of land in Wyoming, Montana and Idaho – larger than Rhode Island and Delaware combined! The park's famously magnificent vistas include forests, lakes, waterfalls and petrified forests, all home to a treasure of American wildlife.  But beneath its surface beauty, that's where Yellowstone National Park gets even more interesting. It's over top of a giant volcanic...