Many mountain districts which now support small glaciers only, or none at all, were once nearly or quite submerged beneath snow and ice. If once covered by an ice carapace or cap, our present interest in them begins at that stage of the receding hemicycle _when the rock surface has made its reappearance above the surface of the snow-ice mass_. At this stage intensive frostwork, the characteristic high level weathering, begins, and cirques develop above the scars of those earlier amphitheaters formed in the advancing hemicycle. =The piedmont glacier.=—In this early stage of transition from the ice cap to the mountain glacier, the ice flows outward to the mountain front in ill-defined streams divided by the projecting ridges, and upon reaching the mountain front these streams deploy upon it so as to coalesce in a great stagnant ice apron whose upper surface slopes gently forward at an angle of a few degrees at the most (Fig. 408, stage I). This is the _piedmont glacier_, a type found to-day in the high latitudes of Alaska and in the southern Andes (Fig. 409 and pl. 18 B). [Illustration: FIG. 409.—Map of the Malaspina glacier of Alaska, the best known of existing piedmont glaciers (after Russell).] During this stage the cirques may be but poorly defined, and ice flows in both directions from rock divides so that the streams transect the range, and later, after the glaciers have disappeared, may expose a pass smoothed and polished upon its floor and with striæ directed in opposite directions from the highest point. The pass of the Grimsel in Switzerland furnishes an excellent illustration of such earlier transection of the range. [Illustration: FIG. 410.—Map of the Baltoro glacier of the Himalayas, a typical glacier of the dendritic type.] =The expanded-foot glacier.=—As air temperatures continue to become milder, the glacier streams within the mountains are less deep and hence more clearly defined, and instead of coalescing upon the mountain foreland, they now issue from the mountains to form individual aprons and are described as _expanded-foot glaciers_ (Fig. 408, stage II, and Fig. 292, p. 264). [Illustration: FIG. 411.—The Triest glacier, a hanging glacieret separated from the Great Aletsch glacier to which it was lately a tributary.] =The dendritic glacier.=—Still later in the hemicycle nourishment of the glaciers is diminished as depletion from melting increases, so that the glacier streams no longer reach to the mountain front. Branches continue to enter the main valley from the several side valleys like the short branches of a tall tree, and because of this arrangement such a glacier may be described as a _dendritic glacier_ (Fig. 408, stage III, and Fig. 410).