The Sea Around Us by Rachel Carson

Author:Rachel Carson
Language: eng
Format: epub, mobi
Publisher: Open Road Integrated Media LLC
Published: 2010-06-14T16:00:00+00:00

Some of our Stone Age ancestors must have known the rigors of life near the glaciers. While men as well as plants and animals moved southward before the ice, some must have remained within sight and sound of the great frozen wall. To these the world was a place of storm and blizzard, with bitter winds roaring down out of the blue mountain of ice that dominated the horizon and reached upward into gray skies, all filled with the roaring tumult of the advancing glacier, and with the thunder of moving tons of ice breaking away and plunging into the sea.

But those who lived half the earth away, on some sunny coast of the Indian Ocean, walked and hunted on dry land over which the sea, only recently, had rolled deeply. These men knew nothing of the distant glaciers, nor did they understand that they walked and hunted where they did because quantities of ocean water were frozen as ice and snow in a distant land.

In any imaginative reconstruction of the world of the Ice Age, we are plagued by one tantalizing uncertainty: how low did the ocean level fall during the period of greatest spread of the glaciers, when unknown quantities of water were frozen in the ice? Was it only a moderate fall of 200 or 300 feet—a change paralleled many times in geologic history in the ebb and flow of the epicontinental seas? Or was it a dramatic drawing down of the ocean by 2,000, even 3000 feet?

Each of these various levels has been suggested as an actual possibility by one or more geologists. Perhaps it is not surprising that there should be such radical disagreement. It has been only about a century since Louis Agassiz gave the world its first understanding of the moving mountains of ice and their dominating effect on the Pleistocene world. Since then, men in all parts of the earth have been patiently accumulating the facts and reconstructing the events of those four successive advances and retreats of the ice. Only the present generation of scientists, led by such daring thinkers as Daly, have understood that each thickening of the ice sheets meant a corresponding lowering of the ocean, and that with each retreat of the melting ice a returning flood of water raised the sea level.

Of this ‘alternate robbery and restitution’ most geologists have taken a conservative view and said that the greatest lowering of the sea level could not have amounted to more than 400 feet, possibly only half as much. Most of those who argue that the drawing down was much greater base their reasoning upon the submarine canyons, those deep gorges cut in the continental slopes. The deeper canyons lie a mile or more below the present level of the sea. Geologists who maintain that at least the upper parts of the canyons were stream-cut say that the sea level must have fallen enough to permit this during the Pleistocene glaciation.

This question of the farthest retreat of the sea into its basins must await further searchings into the mysteries of the ocean.

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