About four million years ago, this part of the North American Plate slid over the Yellowstone hot spot, and in southwestern Montana its deep thermal energy helped shape the mountains and valleys by bulging the crust and stretching it until it broke into blocks separated by steep faults that moved up or down relative to adjacent blocks. This site in the Red Rock Valley is one of the down-dropped blocks, while the Tendoy Mountains to the west were uplifted, with the Red Rock fault marking the break between them. The fault can be seen along the foot of the mountains nearest the rest area, and the triangular faces that terminate the ridges are evidence that it is very young. It ruptured as recently as 3000 years ago, and earthquakes indicate that it is still actively moving. About 95 million years ago, a small herbivorous dinosaur called Oryctodromeus lived in this area in underground burrows. In 2006, paleontologists discovered the fossilized skeletons of an adult Oryctodromeus and two juveniles in an ancient burrow nearby. The skeletons showed that the animal was specially adapted to digging, with strong forearms, shoulders, and a beak, and they also indicated that adults took care of the young. Paleontologists do not know why the long-legged Oryctodromeus chose to den underground, but it may have helped it avoid extremes of hot and cold, evade predators, and raise its young.