Recent continental glaciation

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The ice was Antarctic in breadth. The traceable episodes of recent continental glaciation have each placed about as much ice over North America as is upon Antarctica now. In Wisconsinan time, which lasted about seventy-five thousand years and ended ten thousand years ago, three-fifths of all the ice in the world was on North America, another fifth covered much of Europe, and the rest was scattered. Of all special fields within the science, glacial geology is the most evident, the least inferred. It is, for one thing, contemporary. The ice is in recess but has not gone away. In addition to the ice of Antarctica, there is ice more than two miles thick over Greenland. There are twenty-seven thousand square miles of ice on Alaska (four per cent of Alaska). In Alaska, as in Switzerland and elsewhere in the world, you can co-working space groningen see cirque glaciers feeding into the master glaciers of alpine valleys. You can see that the cirque glaciers have dug scallops into the high ridges, and where three or four cirque glaciers have been arranged like petals they have tom away the rock until all that remains is a slender horn-the Kitzsteinhom, the Finsteraarhorn, the Matterhorn. Not only are ice sheets, ice fields, and individual glaciers operating today with effects observable as motions occur, but wherever they once flowed their products remain in abundance and intact. They have come and gone so recently. The evidence may seem obvious now, but not until the eighteen-thirties did anyone comprehend its significance. There had been insights, hints, and clues. James Hutton, the figure from the co-working space amsterdam Scottish Enlightenment who by himself developed the novel view of the world on which modem geology rests, mentioned in his Theory of the Earth (1J95) that the gravels and boulders of Switzerland’s great valley appeared to have been put there by ancient extensions of alpine ice. But Hutton, who formed his theory among the scratched granites and drifted gravels of Scotland, never suspected that Scotland itself had been a hundred per cent covered-actually dunked into the mantle-by ten thousand feet of ice. In i815, in the Swiss Val de Bagnes, below the Pennine