The canyons of the Teton Range lie almost entirely within Grand Teton National Park in the U.S. state of Wyoming. Ranging from to less than in length and up to deep, the canyons were carved primarily by glaciers over the past 250,000 years. The canyons in the Teton Range descend in altitude generally west to east and many have lakes at their outlets. The lakes were created by terminal moraines left behind by the now retreated glaciers. A few of the canyons have small glaciers that were created mostly during the Little Ice Age (1550-1850). Fast retreating Schoolroom Glacier is a tiny glacier located at the head of the South Cascade Canyon. Most of the canyons have streams from which rain and snowmelt flow towards Jackson Hole valley, and due to the sometimes rapid altitude descent, waterfalls are common. The canyons offer the easiest hiking access into the Teton Range.