=Wear of drift in transit.=—Drift carried at the bottom of the ice is subject to notable wear. The materials in transportation abrade one another and are abraded by the bed over which they pass. Englacial drift is subject to less wear because it is commonly more scattered. Superglacial drift is worn little or none while it lies on the surface of the ice; but in so far as superglacial or englacial drift is derived from the basal load, it may show the same evidences of wear as the basal drift itself. Superglacial drift often reveals its history in this way. [Illustration: +Fig.+ 274.—Thickening of the upturned layers of ice.] _Deposition of the Drift._ 1. =Beneath the body of the ice.=—During the advance of a glacier, deposition may take place both beneath the body of the ice and beneath its end and edges. Deposition beneath the body of the ice is liable to take place wherever the topography favors lodgment, or wherever the ice is overloaded. The topography favoring deposition is much the same as that favoring erosion, but the two processes are not favored at the same point. Erosion is greatest on the “stoss” side of an obstruction (the side against which the ice advances), and deposition on the lee side. The ice is likely to be overloaded (1) just beyond a place where conditions have favored the gathering of a heavy load, and (2) where the ice is rapidly thinning. On the whole, however, the deposition of material beneath the main body of a glacier is much more than balanced by erosion in the same position. [Illustration: +Fig.+ 275.—Glacier building an embankment. Southeast side of McCormick Bay, North Greenland.]