East of the Teton Fault, in the Jackson Hole area, another great earth block lies deeply buried beneath debris brought down into the basin by mountain streams and glaciers. Changes wrought by the great glaciers of the Ice Age have given the region much of its distinctive character. Glacial erosion is strikingly evident in the sharply chiselled peaks, the U-shaped canyons and the profound basins (“cirques”) at their heads, and the numerous little alpine tarns (lakelets occupying ice-gouged basins). The irregular wooded ridges of Jackson Hole, on the other hand, are due to glacial deposition, being composed of bouldery debris heaped up by the ice. Some of these moraines form the dams which enclose the beautiful lakes at the foot of the Teton Range—Phelps, Taggart, Bradley, Jenny, Leigh, and Jackson Lakes. The broad terraced plains of Jackson Hole are for the most part great sheets of gravel spread out on the valley floor by the glacial streams of the Ice Age. Small glaciers still found among the Teton Peaks are now believed to be youthful ice bodies only a few thousand years old, rather than the dwindling remnants of great glaciers of the Ice Age, as was formerly thought. A fuller account of the geologic features is given on the reverse side of the topographic map of Grand Teton National Park, for sale at the museum. Wildlife The Jackson Hole country, long famous for its big game, is the home of one of the world’s largest elk herds. The elk, or wapiti, have been the most important big-game animals in Jackson Hole since the occupancy of white men. In the spring they leave the low country of the park and the National Elk Refuge, near the town of Jackson, and move toward the highlands surrounding the valley. When snowfall comes in the high country the elk return to the refuge, which is administered by the Fish and Wildlife Service of the Department of the Interior. Shiras moose, the most commonly seen big game animal, is frequently observed in the smaller ponds and marshy meadows. The moose, largest member of the deer family, is not as wary as other deer. Mule deer are increasing in the park and environs, and, though quite shy, are often seen along the trails by hikers and horseback riders. Small herds of bighorn, or Rocky Mountain sheep, range in isolated sections of the park, and bears may be found in the mountains and canyons. Beavers, martens, minks, weasels, coyotes, marmots, conies, and rabbits inhabit the park, and ground squirrels and chipmunks are numerous. More than 100 species of birds may be identified by the careful observer. Trees and Plants