A glacier deposits most rock debris at its terminus. The steep snout of any major glacier is a dangerous place to approach closely because rock debris almost constantly falls, rolls, and slides down the melting ice faces. Much of this debris collects at the ice margin, and if the margin stays in one place long enough a ridge-shaped end moraine of rock debris forms along the ice front (fig. 14). If such a moraine forms across the front of a glacier at its farthest advance it is called a terminal moraine. End moraines that form as the ice recedes are called recessional moraines (fig. 15). Ridges of rock debris that form along the sides of a glacier are called lateral moraines (fig. 12). Some recent moraines of modern glaciers are only a few feet away from the present ice margin; others, formed thousands of years ago during the most recent major glaciation, are on ridgetops and valley sides or floors miles away from modern glaciers. By examining the shape and location of these moraines, we can reconstruct the size and character of past glaciers, as we will see in the next section. [Illustration: Glacier-smoothed and grooved rock along the Wonderland Trail between Indian Bar and Panhandle Gap. (Fig. 13)] [Illustration: A muddy grayish-blue lake several hundred feet long lies behind a small horseshoe-shaped end moraine of Flett Glacier, on the northwest side of Mount Rainier. The glacier is mostly out of view to the left. (Fig. 14)] Glaciers erode, transport, and deposit huge quantities of rock debris. So do their coworkers, the melt-water streams. These turbulent streams flow from tunnels beneath every glacier, and their degree of muddiness roughly shows how active the glacier is. Glaciers that move very slowly, or that are stagnant, produce relatively clear melt water because they are not actively eroding bedrock. In contrast, streams of muddy water that look like chocolate milk often come from very active or “live” glaciers. These streams carry rock debris ranging from flour-size particles to large boulders. You can sense the carrying power of this swiftly moving water on warm summer days, when large cobbles and boulders are bumping along in a stream swollen by rapid glacier melting. Although you can rarely see these boulders, you can hear their constant low thunder. Their repeated impacts on other boulders in the streambed will vibrate the nearby streambanks beneath your feet. Hikers often find that a melt-water stream safe to cross in the early morning of a warm summer day is an impassable torrent at the same spot by early afternoon. [Illustration: Four curved recessional moraines are spread over a distance of 2,000 feet on the valley floor of Fryingpan Creek. They were formed within the last few hundred years as Fryingpan Glacier lost volume and shrank back toward its present position above a line of cliffs. (Fig. 15)]