The Teton Mountain Range is one of the most spectacular and unusual geological structures in the world. Tectonic activity over millions of years, combined with massive erosion from water and glaciers, created the dramatic appearance we see today. The Teton range arose from a "hinge fault" in the crust of the earth. The face of the range was lifted almost vertically while the valley floor dropped. Glacier flows over millions of years made the valley floor virtually flat up to the base of the mountains. This valley is called "Jackson Hole" whereas "Jackson" is the name of the town at the south end of the valley. The "hinge" on the west side of the Teton Range lies roughly along today's Wyoming/Idaho border. This explains why the West slope is gradual with rolling foothills, whereas the East slope is like a vertical wall, rising up from the valley floor with no foothills other than some eroded moraine along the base. This dramatic lift on the east slope also accounts for the many lakes that lie along the fault line. The photos in this gallery depict how the East and West slopes differ visually and geologically. The rolling hills on the West side are bisected by meandering canyons that rise gradually, whereas the canyons on the East side mostly rise steeply into the upper reaches of the range. A key to distinguishing which side these photos are taken from is the "lean" of the Grand Teton itself. Viewed from the West (Idaho) side, the tip of the Grand seems to lean to the left, whereas from the East side it appears to lean to the right. Most of the photos of the West slope were taken from Alta WY, with views (from left to right) of Mount Owen, Grand Teton, Middle Teton, and South Teton. The pictures from the East side were taken from various locations in Grand Teton National Park, including the center of the valley near the town of Kelly, at the north end of the park near Oxbow Bend and Jackson Lake, and the Cathedral Group Turnout, just north of Jenny Lake, where one see breathtaking views of Grand Teton, Teewinot Mountain, and Mount Owen.
