The Ross Sea is floored with glacial debris upon which the sea has exercised no selective action whatsoever. The sediment is apparently being laid down in the same condition in which it is being released by the melting ice. Distance from the ice barrier and depth of water have no effect on texture. The Antarctic continent is surrounded by a zone of this material 200 to 500 miles wide, which mantles the continental shelf and slopes. It might be termed a marine till. The percentages of clay and colloid run unusually high. Such complete lack of sorting is unusual in either a deep or shallow water marine sediment, even in the Arctic where the deposits are also largely laid down by floating ice. Among the heavy minerals, those of the ferro-magnesian group are unusually abundant. All the heavies are comparatively unaltered, which is undoubtedly due to glacial conditions. Higher grade metamorphic minerals are notably absent. In the finer grades chemically decomposed material is found which is probably due to the glacial grinding of shales rather than to present conditions either on land or in the sea.

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