(CBS) For years, CBS News Correspondent Sandra Hughes reports, scientists have tried to understand the dynamic nature of Yellowstone National Park. "It's beautiful up here, everybody should see this at one time or another," says one appreciative observer. Scientist Lisa Morgan may have unlocked one piece in the puzzle, deep below the park's biggest lake. "It is kind of the last unmapped frontier in Yellowstone National Park," says Morgan. What she found looks more like the surface of the moon. Using sonar she's identified a massive bulging dome the size of seven football fields. The only other underwater dome in...