In geologic times these mountains are the energetic teenagers of the Rocky Mountain chain: active, growing, yet sculptured by erosion.
The rise of the Range
Nine million years ago, the earth's crust broke into two rectangular blocks along the Teton fault, a 40-mile-long zone of weakness. Through sporadic movements, the western block hinged skyward to become the Teton Range, while the eastern block tilted downward to form the valley called Jackson Hole. The valley sank four times more than the mountains rose. Displacement continues, and an earthquake producing movement along the fault can occur at any time.