Yellowstone National park is one of the last places in the world where large herds of bison, elk and their predators - the wolves and grizzly bears - still roam. It is an American Serengeti. It is also famous for the geysers, steaming hillsides and boiling mud which delight tourists and animals alike. But this volcanic Eden is touched by tragedy as the super volcano which gave it so much life could also be its destruction. Show less