Great volumes of water pour from melting ice near the lower end of a glacier. These streams, heavily laden with rock flour produced by the grinding action of the glacier and with debris liberated from the melting ice, cut channels through the terminal moraine and spread a broad apron of gravel, sand, and silt down-valley from the glacier terminus (end). Material deposited by streams issuing from a glacier is called _outwash_; the sheet of outwash in front of the glacier is called an _outwash plain_. If the terminus is retreating, masses of old stagnant ice commonly are buried beneath the outwash; when these melt, the space they once occupied becomes a deep circular or irregular depression called a _kettle_ (fig. 12); many of these now contain small lakes or swamps. As a glacier retreats, it may build a series of terminal moraines, marking pauses in the recession of the ice front. Streams issuing from the ice behind each new terminal moraine are incised more and more deeply into the older moraines and their outwash plains. Thus, new and younger layers of bouldery debris are spread at successively lower and lower levels. These surfaces are called _outwash terraces_. [Illustration: Figure 8. _East face of the Teton Range showing some of the glacial features, air oblique view. Cascade Canyon, the U-shaped valley, was cut by ice. The glacier flowed toward the flats, occupied the area of Jenny Lake (foreground), and left an encircling ring of morainal debris, now covered with trees. The flat bare outwash plain in foreground was deposited by meltwater from the glacier. The lake occupies a depression that was left when the ice melted away. National Park Service photo by Bryan Harry._] [Illustration: Figure 9. _Cutaway view of a typical valley glacier._] [Illustration: Figure 10. _Recently-built terminal moraine of the Schoolroom Glacier, a small ice mass near the head of the south fork of Cascade Canyon. The present glacier lies to the right just out of the field of view. The moraine marks a former position of the ice terminus; the lake (frozen over in this picture) occupies the depression left when the glacier wasted back from the moraine to its present position. Crest of the moraine stands about 50 feet above the lake level. Many of the lakes along the foot of the Teton Range occupy similar depressions behind older moraines. Photo by Philip Hyde._]