MOVING CONTINENTS

Evening Star, Issue 19002, 25 July 1925, Page 18

MOVING CONTINENTS

AUSTRALIA’S DRIFT TO' THE NORTH

LAND MASSES AS RAFTS

Australia seems to us a very stable, solid, well-anchored part of tho_ earth’s surface. It does not shake or shiver like New Zealand or Japan, and its volcanoes have been dead for ages. Now scientists assert (says a writer in the Sydney ‘ Sun ’) that the whole continent is drifting slowly northward, and that it has already moved a couple of thousand miles or so. lu a few million years Sydney may have moved into the Northern New State. Then, however, the new State will have moved up past where Brisbane now is. One theorist thinks that Tasmania is a bit that has lagged behind. This, of course, would account for many things. Swift’s flying Island of Laputa could be moved freely up and down or sideways at the will of the philosophers who inhabited it. i If Swift had heard a visitor to tho Pan-Pacific Congress in Sydney describe how Java is moving towards Australia, or Australia towards Java, which comes more or less to the same thing, he would have bowed to what he would have considered an imagination more freakish and wild than his own. To-day even the man in the street is more or less used to the

notion that parts of tho earth’s surface , move slowly up or down, but he can hardly picture a continent adrift from its moor- ' ( mgs and wandering about on tho face of ' the earth. ■ Ho can accept with resignation tho as- ' sertions of the scientists that the earth is a sort of huge top spinning round and round on its axis at a frantic rate, and, at tho same time, rushing round the sun ■ at tho rate of over 500,000,000 miles a year, while it and the sun and the rest of tho solar system are all moving towards a point in the constellation Hercules at the rate of eighteen miles a minute. Now comes a new school of scientists, headed by Alfred Wegener, which slides continents to and fro on the face of the earth, as a chess player moves his pieces. It speaks with confidence of tire march of Australia towards the Equator, tells us how Greenland is moving steadily but slowly towards North America, and how North America has moved away from Europe. To scientists of this school tho continents appear as vast rafts of lighter mattor Testing on tho viscous interior of the earth over which they sometimes slip slowly forwards or backwards. So far these movements have not been measured with any pretence to exactness. It has been asserted, on the strength of-certain determinations of latitude and longitude, that Greenland is moving towards North America. If Australia was ever part of Antarctica, as Wegener assumes, it has already moved a long way towards the Equator. It > would" appear, however, that it has taken j its time about it, and has moved in a 1 very leisurely fashion. Wegener supposes that it is now moving towards the northwest, but does not venture to say how fast it is travelling. If it keeps on going that way long enough, of course, tho Singapore base will be in Australia, and those who object to Australia spending any money on it because it is not in Australia will have the ground cut from under their feet LIKE A JIG-SAW PUZZLE. Three centuries ago Bacon pointed out how curiously the cast coast of South America corresponds to the west coast of Africa. Where Africa bulges out South America curves in—and vice versa* The two, if moved together, would fit into one another very nicely. Wegener accounts for this by supposing that they once did fit into one another, but have drifted apart since cretaceous times. I For he maintains that North America was ' onoe much closer to Europe, and that Greenland, Iceland, Ireland, Scotland, Norway, and Spitzbergen did probably actually form one block of land, which has since been split in two halves, one of which has been still farther split. I South America, like Australia, is pictured as having a drift to tho north, in addition to the movement towards the west, which has carried it away from Africa, which, too, is considered to be moving, or, at least, to have moved, northward- Tho theory of a westward drift of tho Americas accounts very neatly for tho great ranges of mountains which run down tho western side of tho two Americas from Alaska to Cape Horn. Tho westward slide, or creep, brought tho continent up against tho great stable area of the earth’s surface, which underlies most of the basin of the Pacific. And as trio ocean swell rises into huge waves when it meets the resistance of the bot-1 tom on reaching shallows, so huge earth waves 10,000 miles long have been thrown up by the slowly-moving masses of land against the obstacle of the stable bod of tho Pacific. VVegcner accounts in a very similar way for the ranges of high mountains, rising to over 16,000 ft in places, which I traverse New Guinea from end to end. He points out that Torres Straits is a 1 very shallow, and probably comparatively modern, part of the sea bed, and treats 1 Australia and New Guinea ns forming a single land mass. Postulating a former north-eastern drift of this mass, he considers that the mountains have been forced up by pressure against tho stable bottom of the adjacent part ox the Pacific. . . ! A fascinating aspect of this theorv is the ease with which it accounts for the close relations between the animal and plant life of areas now widely sundered by the ocean. Some theorists have made great play with drifting rafts or logs as means for carrying forms across the sea. This theory treats the land masses themselves as rafts. Wild as tho idea seems at first eight, it is almost simple and easy of acceptance when compared to the bewildering maze of land connections across all the oceans of tho globo postulated by various

earlier theorists. Two scientists were discussing the distribution of certain species of snails in the Pacific Islands. One of them contended that the occurrence of closely-re-lated varieties in lands now separated bv wide stretches of deep ocean proved that these lands were formerly joined together. With this the other would not aurcc. Finally he clinched the matter’by saying i “ I don’t believe that tho bottom of the sea was ever raised 15,000 ft to allow vour infernal snails to crawl from one place to another.” WHERE THE DINGOES COME FROM. On tho new theory, Australia and South America were formerly both united to Antarctica, when it had a climate very different to that which it has now, and when they drifted away from it they each carried certain common elements of fauna and flora. There is no need to assume a former land bridge now sunk beneath over 2,000 fathoms of water in the deep sea between Australia and Antarctica, Australia' has slowly slid northward over that sea bottom carrying with it the beeches, the speckled trout, and the other plants and living creatures which South America, on the other side, has also carried northward with it. This northward movement is not tho only element in the development of Australia, according to Wegener. He sees in Australia a composite continent, and tries to work out from its fauna and flora the story of the way in which it has been brought up. In the south-west and west he sees the. oldest element, having affinities with tho flora of Ceylon, Madagascar, South Africa, and of India, To account for this he revives Gondwanaland in another form by supposing that the western part of Australia ‘ once ' adjoined Ceylon India, and Madagascar. Then Western Australia drifted eastward, while India and Ceylon moved northward toward the mass of Asia, Ceylon lagging behind and forming an island. Madagascar lias moved westward. In the marsupials and in many of our plants he sees the Antarctic influence. Just as tho icebergs drifting northwards

| from the frozen continent carry with them earth and stones, so the drifting continent earned plant and animal life. Thirdly, as the continent drifted northward, it approached the islands of the Sunda chain, from which it has received the dingo, the rats and mice, and other rodents (not marsupials), o£_ which there are nearly a hundred species native to Australia. It would seem reasonable to conclude from this theory that the two halves of Australia, east and west,, wore originally separate, and have come together in comparatively recent times, a few geological ag'os ago. There is a good deal to support this on other grounds^