Though the same processes act in much the same manner beneath mountain glaciers, though here upon all parts of the bed, they are, in the earlier stages at least, subordinated to a third process more important than the two acting together. Sculpture by mountain glaciers, instead of reducing surface irregularities and softening outlines, increases the accent of the relief and produces the most sharply rugged topography that is known. In nearly all places where Alpinists resort for difficult rock climbing, mountain glaciers are to be seen, or the evidence for their former presence may be read in unmistakable characters. =Wind distribution of the snow which falls in mountains.=—Until quite recently students of glaciation have concerned themselves but little with the work of the wind in lifting and redistributing the snow after it has fallen. We have already seen that, for the continental glaciers, wind appears to be the chief transporting agent, if we except the marginal lobes where glacier flow assumes large importance. In the case of mountain glaciers, also, we are to find that for the earlier stages particularly wind is of the first importance as a redistributing agent. In the higher levels snow is swept up from the ground by all high winds, and does not find a resting place until it is dropped beneath an eddy in some irregularity of the surface; and if the inherited surface be relatively smooth, this will be found in most cases upon the lee of the mountain crest. In normal cases at least the inherited irregularities of the higher zones of mountain upland are the gentle depressions which develop at the heads of streams. These become, then, the sites of snowdrifts that are augmented in size from year to year, though at first they melt away in the late summer. [Illustration: FIG. 390.—Snowdrift hollowing its bed by nivation and building a delta (at the left). Quadrant Mountain, Yellowstone National Park.]