the northern section of the park lies Jackson Lake, the largest lake in the park at in length, wide and deep. Though Jackson Lake is natural, the Jackson Lake Dam was constructed at its outlet before the creation of the park, and the lake level was raised almost consequently. East of the Jackson Lake Lodge lies Emma Matilda and Two Ocean Lakes. South of Jackson Lake, Leigh, Jenny, Bradley, Taggart and Phelps Lakes rest at the outlets of the canyons which lead into the Teton Range. Within the Teton Range, small alpine lakes in cirques are common, and there are more than 100 scattered throughout the high country. Lake Solitude, located at an elevation of , is in a cirque at the head of the North Fork of Cascade Canyon. Other high-altitude lakes can be found at over in elevation and a few, such as Icefloe Lake, remain ice-clogged for much of the year. The park is not noted for large waterfalls; however, Hidden Falls just west of Jenny Lake is easy to reach after a short hike. From its headwaters on Two Ocean Plateau in Yellowstone National Park, the Snake River flows north to south through the park, entering Jackson Lake near the boundary of Grand Teton National Park and John D. Rockefeller Jr. Memorial Parkway. The Snake River then flows through the spillways of the Jackson Lake Dam and from there southward through Jackson Hole, exiting the park just west of the Jackson Hole Airport. The largest lakes in the park all drain either directly or by tributary streams into the Snake River. Major tributaries which flow into the Snake River include Pacific Creek and Buffalo Fork near Moran and the Gros Ventre River at the southern border of the park. Through the comparatively level Jackson Hole valley, the Snake River descends an average of , while other streams descending from the mountains to the east and west have higher gradients due to increased slope. The Snake River creates braids and channels in sections where the gradients are lower and in steeper sections, erodes and undercuts the cobblestone terraces once deposited by glaciers. Glaciation The major peaks of the Teton Range were carved into their current shapes by long-vanished glaciers. Commencing 250,000–150,000 years ago, the Tetons went through several periods of glaciation with some areas of Jackson Hole covered by glaciers thick. This heavy glaciation is unrelated to