The Ice Age in the North American Arctic 1 



By Richard Foster Flint 



Professor of Geology 

 Yale University 



[With 4 plates] 

 SIGNIFICANCE OF GLACIAL AND INTERGLACIAL AGES 



Arctic North America, 2 in common with the rest of the world, is 

 now emerging from the latest of the series of glacial ages which, as a 

 group, have characterized the last million years or more of geological 

 time. During the glacial ages, each of which was a hundred thousand 

 years or more in length, the mean temperatures at the earth's surface 

 were markedly lower than today. In consequence the proportion of 

 snowfall to rainfall increased, melting diminished, and the accumu- 

 lated snow formed glaciers. These great ice masses spread outward, 

 slowly flowing under their own weight, until they covered one-quarter 

 to nearly one-third of the land area of the world, principally, of course, 

 in high and middle latitudes. In North America and Greenland 

 alone the area covered by ice amounted to 7 million square miles. 



Between the cold glacial ages, warmer times intervened. The rec- 

 ord of the soils formed in temperate latitudes during the warmer, 

 interglacial ages shows that those ages were longer than the glacial 

 ages — one of them probably lasted 300,000 years. The record of the 

 fossil animals and plants entombed in the deposits of interglacial times 

 establishes that one or more of those times was warmer than today ; 

 from this the inference follows that the interglacial ages probably 

 witnessed a more extensive disappearance of ice from the arctic regions 

 than is now the case. In fact, for the world as a whole the present 

 is a time transitional from glacial to interglacial. The great ice 

 sheets that formerly blanketed much of North America and Eurasia 

 have disappeared, but more than 10 percent of the world's land area 

 still remains covered by glacier ice. 



The glacial and interglacial ages together constitute the Pleistocene 

 epoch, the latest epoch in the scale of geological time. Although this 



1 Reprinted by permission from Arctic, vol. 5, No. 3, October 1952. 



* Throughout this paper "Arctic North America" is used in the broad sense and includes 

 "both arctic and subarctic regions. 



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