It has been frequently stated that St. Elias is a volcano, and sea captains sailing on the Pacific have seen what they supposed to be smoke issuing from its summit. As its southern face is composed of the same kind of rocks and is of the same precipitous nature as the southern slope of Mount Augusta, it appears probable that what was supposed to be volcanic smoke was in reality avalanche dust blown upward by ascending air currents. The disintegration of the mountain summits all through the St. Elias region is so great that one constantly wonders that anything is left; yet, except late in the fall, the snow surfaces at the bases of even the steepest cliffs are mostly bare of débris. The absence of earth and stones on the surfaces of the névé fields is mainly due, of course, to the fact that these are regions of accumulation where the winter's snow exceeds the summer's melting. {146} Thus each year the surface is renewed and made fresh and clean, and any débris that may have previously accumulated is concealed. There is another reason, however, why but little débris is found at the bases of the steep precipices. The snows of winter are banked high against these walls, but when the rocks are warmed by the return of the summer's sun the snow near their dark surfaces is melted, and leaves a deep gulf between the upward-sloping banks of snow and the sides of the cliffs. These black chasms are frequently 150 or 200 feet deep, and receive all the débris that falls from above. In this way very large quantities of earth and stones are injected, as it were, into the glacier, and only come to light again far down toward the ends of the ice-streams, where the summer's melting exceeds the winter's supply. [Illustration: PLATE 19. MT. ST. ELIAS, FROM DOME PASS.]