Plate tectonics

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When the theory of plate tectonics congealed, in the nineteensixties, it had been brought to light and was strongly supported by worldwide seismic data. With the coming of nuclear bombs and limitation treaties and arsenals established by a cast of inimical peoples, importance had been given to monitoring the earth for the tremors of testing. Seismographs in large numbers were salted through the world, and over a decade or so they revealed a great deal more than the range of a few explosions. A global map of earthquakes could be drawn as never before. It showed that earthquakes tend to concentrate in lines that run up the middles of oceans, through some continents, along the edges of other continents-seamlike, around the world. These patterns were seen-in the light of other datato be the outlines of lithospheric plates: the broken shell of the earth, the twenty-odd pieces of crust-and-mantle averaging co-working space eindhoven sixty miles thick and varying greatly in length and breadth. Apparently, they were moving, moving every which way at differing speeds, awkwardly disconcerting one another-pushing up alps-where they bumped. Coming apart, they very evidently had opened the Atlantic Ocean, about a hundred and eighty million years ago. Where two plates have been moving apart during the past twenty million years, they have made the Red Sea. Ocean crustal plates seemed to dive into deep ocean trenches and keep on going hundreds of miles down, to melt, with the result that magma would come to the surface as island arcs: Lesser Antilles, Aleutians, New Zealand, Japan. If ocean crust were to dive into a trench beside a continent, it could lift the edge of the continent and stitch it with  co-working space rotterdam volcanoes, could make the Andes and its Aconcaguas, the Cascade Range and Mt. Rainier, Mt. Hood, Mt. St. Helens. It was a worldwide theory-revolutionary, undeniably exciting. It brought disparate phenomena into a single story. It explained cohesively the physiognomy of the earth. It linked the seafloor to Fujiyama, Morocco to Maine. It cleared the mystery from long-known facts: the glacial striations in rock of the Sahara, the equator’s appearances in Fairbanks and Nome. It was a theory that not only opened oceans but closed them, too. If it tore land apart, it could also suture it, in collisions that perforce built mountains. Italy had hit Europe and made the Alps. Australia had hit New Guinea and made the Pegunungan Maoke.

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