Probable Disintegration of Antarctica

Abstract

The writer's research life has coincided fairly closely with the vast discoveries made in thi c ntury s nce he first joined the Sc tt Expedition to Antarctica in 1910. Nothing was known within the coasts of Antarctica until Scott had returned; indeed, until the end of 1904 the map merely showed a pear-shaped outline extending around the South Pole. In my first long memoir, which appeared in this Journal in 1914, I discussed generally the structure of Antarctica, and I especially stressed the resemblance between Antarctic and Australian structure ('Physiography and glacial geology of East Antarctica'; Geogr. J. 44 (1914) 365-82; 452-67; 553-71). I suggested that a broad syncline or downfold below sea level might extend from the Ross Sea to the Weddell Sea?somewhat as the Tasman Sea separated the folded New Zealand Ridge from the Horsts of Australia. Possibly this marine channel was present in midTertiary times. I have seen these suggestions to a considerable degree corroborated by the con? clusions ofthe I.G.Y. researches as seen in the recent topographic map published by the Scientific American in September 1962 (Antarctica: prepared by the American Geographical Society for the United States Antarctic Research Program, with a grant from the National Science Foundation: 1:5M. 1962). Two techniques have been developed in the Antarctic in the last thirty years? exploration by air, and echo-sounding through the ice cap. I may instance a few errors on the earlier maps. In 1914 Amundsen, as he sledged over the Ross Ice Shelf to the Pole, gave it as his opinion that 'Carmen Land' blocked my hypothetical geosyncline. This land was illusory: Scott's ship sailed over several so-called 'lands' in 1911 near Cape Adare (near d Fig. 1). Mawson found that many landfalls cited by Wilkes in 1840 were greatly out of position in this area. Wilkins, on his first flight in December 1928 charted 'Stefansson Strait' in approximately lat. 71 ? in such a position as to divide Graham Land from the Continent; this was later found to be an error. In 1940 was published in the Regionale Geologie der Erde of Leipzig (Bd. I: Die alten Kerne) my geological account of Antarctica which, though written in 1934, was more complete than anything that had been published before, and which was illustrated by a block diagram of Antarctica. In 1935 Ellsworth flew across from the Weddell Sea to the Ross Sea, and found that his 'Sentinel Range' (c) much prolonged the 'Antarctic-Andes' towards the Ross Sea. However, Byrd's aviator (Anderson) in 1936 reported that the 'Great Horst' extended for some 180 miles beyond the South Pole towards the Weddell Sea. The new sonic data reported as late as 1960 gave sonic and other inform? ation which seemed wholly to block the suggested geosyncline. The latest map, the American one discussed here, shows that the geosyncline, some 2000 miles long, and varying in width from 200 miles downwards until it narrows near the Horlick Mountains at the point marked * on Figure 1, is an actual feature. Recent soundings have shown that the Ross Shelf extends south-east for some 500 miles to the