Cavernous Weathering in the Taylor Dry Valley, Victoria Land, Antarctica
TAYLOR VALLEY (77° 33′ S., 163° 25′ E.) is part of a deglaciated valley complex called the McMurdo Oasis, which is located about 80 km to the west of Ross Island across McMurdo Sound. Since the IGY many New Zealand and American geological parties have worked in this area1–3, which is easily accessible by helicopter from Scott Base and McMurdo Station at the southern end of Ross Island. Now that the topographical and geological reconnaissance stage has been completed and adequate maps cover the 2,500 km2 of the McMurdo Oasis, more attention is being devoted to the study of various anomalies and problems.
Multiple Glaciation in the McMurdo Sound Region, Antarctica: A Progress Report
At least four major Quaternary glaciations, each successively less extensive than the former, are recorded in the McMurdo Sound region of Antarctica. Deposits of the earliest recognized glacial advance occur high on ridges and flat areas. The deposits are 2,000 feet above the valley floor, are badly weathered, and have little or no morainal form. Ice of this glaciation filled all the valleys and must have filled McMurdo Sound to an elevation of 2,000 feet. Deposits of the next two succeeding glaciations are distributed around the sound as well-preserved, but considerably subdued, moraines of both outlet and alpine glaciers. During the earlier of these two glaciations, alpine glaciers reached the expanded Koettlitz and Ferrar outlet glaciers. Outlet glaciers filled the southern part of McMurdo Sound to an elevation of about 1,000 feet. During the latter of these two advances many alpine glaciers did not reach the outlet glaciers. The latest major glaciation is represented by well-preserved ice-cored moraines. Number and position of deltas in drained glacier-ice-blocked lakes suggest the possibility of three Stillstands or minor advances during this glaciation. Radiocarbon dating of algae in drained ponds indicates a minimum age of 6,000 years for this glaciation.
Bottom Deposits of the Ross Sea
ABSTRACT 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.