Most of the material which was englacial during the transportation becomes either subglacial or superglacial before deposition, for it ordinarily reaches the bottom or the top of the ice before being deposited. Where the ends or edges of a glacier are vertical or nearly so, as in the high arctic regions, deposition may take place from the englacial position directly. =Distinctive nature of glacial deposits.=—The deposits made by glaciers are distinctive. In the first place the ice does not assort its material, and bowlders, cobbles, pebbles, sand, and clay are confusedly commingled (Fig. 279). In this respect, the deposits of ice differ notably from those of water. Furthermore, many stones of the drift show the peculiar type of wear which glaciers inflict. They are not rounded as the stones carried by rivers, though they are notably worn. Many of them have subangular forms with planed and beveled faces, the planes being striated and bruised (Fig. 254). The absence of stratification, the physical heterogeneity, and the striation of at least a part of the stones are among the most distinctive characteristics of glacial drift. A not less real though less obvious characteristic is the constitution of the fine material, for it is in general not the product of rock decay, but of rock grinding. The fine material handled by streams (except glacial streams) on the other hand, is usually the product of rock decay. [Illustration: +Fig.+ 280.—Roche moutonnée, Victoria Harbor, B. C.] =Glaciated rock surfaces.=—Another distinctive mark which a glacier leaves behind it is the character of the surface of the rock on which the drift rests. This is generally smoothed by the severe abrasion to which it has been subjected, and the smoothed surfaces are marked by grooves and striæ, similar to those on the stones of the drift (Figs. 255 and 256). Other distinctive features of a glaciated area are the rounded bosses of rock (_roches moutonnées_, Fig. 280; see also surface about the lakes, Fig. 261), the rock basins, the lakes (Fig. 261), ponds, and marshes, and the peculiar topographies resulting from the unequal erosion, and the still more unequal deposition of the drift. Surface bowlders, often unlike the underlying formations of rock, and sometimes in peculiar and apparently unstable positions, are still another mark of a glaciated area. GLACIO-FLUVIAL WORK.