Charles Keyes

Document Type



The old-fashioned notion of a gargantuan ice-cap, so huge as to occupy half of the earth's hemisphere and miles in thickness, was as we now well know, not a creation of the geologist but of the zoologist, a fancy drawn upon to support the theological idea of special creation of life on the globe. It was zoologist Agassiz's last stand against the rapidly growing Darwinian revolution through evolution. Lately, this all but forgotten concept has been revived to explain submarine terraces, 50 to 300 feet below sea-level, the continental shelf at 600 feet and even deep-sea plains trenched by canyons a mile below sea-level. But an ice-cap is, as we now know, not the gargantuan affair so often pictured, which latter is really a composition of half a dozen different glaciations. On the other hand, the dimensions of Iowa's last great ice-sheet, about the largest known, are fairly well determined. It probably did not exceed a thousand feet in thickness. At this figure the icecap when melted, would return to the ocean water sufficient to raise the sea level only about 2 feet. If, for fancy, the ice were half a mile thick, the sea level would scarcely rise 5 feet. These are maximum figures. The flooded benches under sea, on the continental shelf, will have to be accounted for by some other means than as directrices of melt-waters from a great ice sheet.

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Proceedings of the Iowa Academy of Science





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©1940 Iowa Academy of Science, Inc.



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