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2008年3月16日 (日)


Science For All Americans 勝手に翻訳プロジェクト Chapter 10: HISTORICAL PERSPECTIVES



As soon as fairly accurate world maps began to appear, some people noticed that the continents of Africa and South America looked as though they might fit together, like a giant jigsaw puzzle. Could they once have been part of a single giant landmass that broke into pieces and then drifted apart? The idea was repeatedly suggested, but was rejected for lack of evidence. Such a notion seemed fanciful in view of the size, mass, and rigidity of the continents and ocean basins and their apparent immobility.


ほぼ正確な世界地図が明らかになり始めるのとほぼ時を同じくして、幾人かの人々は、アフリカ大陸と南アメリカ大陸とが、まるで巨大なジグソーパズルのように、互いにぴったりとくっつき合えるかのように見えることに気がついた。二つの大陸がかつて一つの巨大な陸地の一部であって、それが部分部分とに分かれて離れ離れになっていったものだということがあり得るのだろうか? この着想(idea)は繰り返し示唆されたが、証拠が無いことによってその度に棄却された。大陸と海洋[1]の大きさや質量や固さ、そして陸も海も明らかに動いていないことから見れば、そのような考えは空想だと思われたのである。

[1] ocean basins なので単に海というよりは、地形としての海のことを指しているのでしょう。ただ、日本語としたらどんな言葉がいいか悩んでいます。「海洋の固さ」と言ってしまってはもちろんとても変なので、変えたいところなのですが。


Early in the twentieth century, however, the idea was again introduced, by German scientist Alfred Wegener, with new evidence: The outlines of the underwater edges of continents fit together even better than the above-water outlines; the plants, animals, and fossils on the edge of one continent were like those on the facing edge of the matching continent; and—most important—measurements showed that Greenland and Europe were slowly moving farther apart. Yet the idea had little acceptance (and strong opposition) until—with the development of new techniques and instruments—still more evidence accumulated. Further matches of continental shelves and ocean features were found by exploration of the composition and shape of the floor of the Atlantic Ocean, radioactive dating of continents and plates, and study both of deep samples of rocks from the continental shelves and of geologic faults.


[1] Wikipedia を参照してみましたが、ドイツ人ということでドイツ語読みでアルフレート・ヴェーゲナーとした方がよいでしょうか? たまたま英語読みの方がなじみがあったのでこうしてありますが。


By the 1960s, a great amount and variety of data were all consistent with the idea that the earth's crust is made up of a few huge, slowly moving plates on which the continents and ocean basins ride. The most difficult argument to overcome—that the surface of the earth is too rigid for continents to move—had proved incorrect. The hot interior of the earth produces a layer of molten rock under the plates, which are moved by convection currents in the layer. In the 1960s, continental drift in the form of the theory of plate tectonics became widely accepted in science and provided geology with a powerful unifying concept.



The theory of plate tectonics was finally accepted because it was supported by the evidence and because it explained so much that had previously seemed obscure or controversial. Such diverse and seemingly unrelated phenomena as earthquakes, volcanoes, the formation of mountain systems and oceans, the shrinking of the Pacific and the widening of the Atlantic, and even some major changes in the earth's climate can now be seen as consequences of the movement of crustal plates.




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