The Two Medicine Formation is a late Cretaceous geological formation that was primarily deposited in North Central Montana 84 to 71 million years ago about the same time as the Judith River Formation, See Map - pink area. The Two Medicine is found along the east flank of the Rocky Mountains and represents the upland area of the Cretaceous Seaway while the Judith River Formation represents the lowland area. Although deposited in the roughly the same period the Two Medicine has yielded an amazing