The Mammoth Graveyard is a region in Prehistoria. It is located directly north of the Northern Jungle and connects to the Volcano Slopes. The Vipers around the volcano used the graveyard as a source for bones and tusks to craft weapons with.
The Hero and his Dog journeyed through the graveyard to reach the Volcano Slopes, and were set upon by a pack of Vipers. They defeated the Vipers and their commander, and met with an inhabitant of the swamp. Told that Elizabeth had sent them, he opened the gate to the Volcano Slopes for them, and gave them the Heal formula.