Antarctica’s link to a huge geological theory

Press, 28 October 1981, Page 25

Antarctica’s link to a huge geological theory

By

GEOFF MEIN

New Zealand scientists leave Christchurch this week to take part in a major international 'study of the Antarctic’s Northern Victoria Land — a region thought to contain crucial evidence supporting the theory of continental drift. The region forms a terminus at the Pacific end of the Trans-Antarctic mountain range, but instead of the mountains sloping gently to ' the sea coast, they are truncated abruptly as if "chopped off by a meat cleaver.” Geologists assume this to mean that at some time there was a continuation of the range. Some claim to have found evidence that the missing links to the Trans-Antarctic mountain chain now lie in Western Tasmania and Southern Australia. Dr Malcolm Laird, of the New Zealand Geological Survey at the University of Canterbury, is convinced that Tasmania at one time formed part of the range, less than 300 km from Northern Victoria Land. (The' regions at present lie some 3700 km apart). The hypothesis — often taught as gospel in secondary schools — is that several land masses, including South America, Africa, Australasia and the Antarctic once formed part of a supercontinent called Gondwanaland. They are thought to have been drifting apart ever since. It remains a hypothesis because “only about 95 per cent of the world’s geologists agree with it. (Some older generation Russians refuse to accept the theory).” There also exists a scientific reluctance to become committed to what remains, essentially, a convenient explanation. Most of those willing to accept the hypothesis do so because it is “the only one which anyone can think of that fits the bits (of scientific evidence) that everybody brings out.” Dr Laird said the theory of continental drift was like the theory of evolution: “People accept it

because it explains everything simply.” He leads a four-man New Zealand party south in a few days to "tie together loose ends . . . and hopefully discover enough to write a final survey of the area with some confidence in relation to the correlation between continents.” He had studied rocks and fossils in Northern Victoria Land which were “identical” to those of the same age in southern regions of Australia. , “In some cases the similarities are so striking that if it was not for the absence of snow in Australia, you would think you were in Antarctica.” Sixty scientists from the United States, New Zealand, Australia and West Germany will be looking at different areas of Northern Victoria Land this summer. As well as gathering evidence to support continental

drift, geologists are interested in learning more about the relationship between the Trans-Antarctic mountains and the massive Antarctic Shield, which consists of rocks up to 4000 m years old. Most major continents have central stable shield areas which have remained unchanged geologically for more than 500 m years. Geological activity occurs around the edges where younger rocks — some 300 m years old — pile up against the shield. Northern Victoria Land’s mountain range forms a belt of exposed rocK up to 400 km wide, making it an ideal site for study in the Antarctic. Anotner reason for the Northern Victoria Land project is to look for resources. Faced with budget restraints, the American Antarctic research programme has to justify itself, so “resource study” is one of the stated

objectives of the project. “Once you start looking at scientific results you can make predictions about resources based on what is found in other continents. If it can be shown that Northern Victoria Land was once joined to a region of Australia which contains minerals, such as zinc, the economic implication becomes obvious,” said Dr Laird. Studies in the region have in the past been restricted to surface travel by dog sledge, motor toboggan or man-haul-ing. Large areas of difficult terrain have not been explored and were unlikely to be satisfactorily covered by ground v ork. Because New Zealand has no helicop'ers in the Antarctic, they “invited” the Americans to join the Northern Victoria Land study. Although the New Zealand scientists accept that without American logistic support the project would never have got off the ground, they were disappointed that the Americans had virturally “taken over.” New Zealand had hoped to have 20 scientists involved; but they have been cut back to 14. Dr Laird said that although New Zealand was disappointed, there was no resentment. . “To get the logistic support, it is a sacrifice we have to make.” This will be Dr Laird's sixth visit to the Antarctic since 1960 when, as a geology masters student at Auckland

University, he went south “partly by accident.” “Desperately short of money” to continue his studies, the young Laird answered an advertisement to join an Antarctic expedition. He realised that as a “mere” student his chances were slim, but "by some fluke” he was accepted. Accompanied by two sur-

veyors, his job was to collect rocks and try to produce a geological map of the Nimrod Glacier region, which was “totally unexplored.” Although much of his time was spent “chasing sledges and things,” he did find rocks and fossils which turned out to be internationally important geologically. Since then, his special interest has been, in the rocks of the Trans-Antarctic mountains. Although he admits that

finding evidence to support continental drift is like “preaching to the converted.” he sees this summer’s project as a special challenge. “The geology of the Antarctic is still relatively unknown. There are always surprises. Even in an area you have visited before, you will find something new. "You can be sure that any trip, unless it is a complete washout through crashed planes or hideous weather, is going to end up with some rewards.”