Where ice-caps are developed on plateaus whose borders are trenched by valleys, ice-tongues from the edge of the ice-cap often extend down into the valleys and give rise to one type of _valley glacier_ (Figs. 224 and 227). A second and more familiar type of valley glacier occupies mountain valleys, and is the offspring of mountain snow-fields (Fig. 228). The former are confined chiefly to high latitudes, and are distinguished as _polar_ or _high-latitude_ glaciers (Figs. 227 and 229); the latter are known as _alpine_ glaciers (Figs. 228 and 230). The end and side slopes of polar glaciers are, as a rule, much steeper than those of alpine glaciers. When a valley glacier descends through its valley to the plain beyond, its end deploys, forming a fan (Fig. 231). The deploying ends of adjacent glaciers sometimes merge, and the resulting body of ice constitutes a _piedmont glacier_ (Fig. 232). At the present time, piedmont glaciers are confined to high latitudes. In some cases the snow-field that gives rise to a glacier is restricted to a relatively small depression in the side of a mountain, or in the escarpment of a plateau. In such cases the snow-field and glacier are hardly distinguishable, and the latter descends but little below the snow-line. In many cases it does not even enter the narrow valley which leads out from the depression occupied by the snow-field. Such a glacier is nestled in the face of a cliff, and may therefore be called a _cliff glacier_[124] (Figs. 233 and 234). The snow-field of a cliff glacier is sometimes no more than a great snowdrift, accumulated through successive years. Cliff glaciers are often as wide as long, and are always small, and between them and valley glaciers there are all gradations (Fig. 235). Occasionally the end of a valley glacier, or the edge of an ice-sheet reaches a precipitous cliff, and the end or edge of the ice breaks off and accumulates like talus below. The ice fragments may then again become a coherent mass by regelation, and the whole may resume motion. Such a glacier is called a _reconstructed glacier_. The precipitous cliffs of the Greenland coast furnish illustrations. [Illustration: +Fig.+ 232.—The Malaspina glacier, Alaska; the best known example of a piedmont glacier. (Russell.)] [Illustration: +Fig.+ 233.—A cliff glacier. North Greenland type. North side of Herbert Island, Inglefield Gulf. The lower half of the white area is snow, and snow talus. So also are the white patches to the right. The height of the cliff is perhaps 2000 feet. The water in the foreground is the sea.] [Illustration: +Fig.+ 234.—Chancy glacier; a cliff glacier of the Montana type. (Shepard.)]