300 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 8 



the limits of the ice sheet, we find that the area covered by the ice 

 was not concentric with the North Pole. It extended much farther 

 south over Europe and the east of North America than it did over 

 Asia and the east of America ; in fact the center of the ice sheet was 

 in the middle of Greenland, 20° of latitude from the Pole. 



The answer to both these problems is the same and gives strong 

 support to the correctness of the theory. If the area around the 

 North Pole were land instead of sea, we should have at the Pole a 

 great ice sheet, similar to that over Greenland and the Antarctic, 



.CASilSA 



sSSS&te 



ADVANCE AND FUTR,EAT OF ICE 



TIME 

 Figure 4.— Effect of two cycles of solar radiation on glaciation. 



rising many thousands of feet above sea level. With increased pre- 

 cipitation this ice cap would increase in height and extent and grow 

 symmetrically about the Pole. With the present distribution of land 

 and sea such a north polar cap is not possible. The ice which forms 

 in the Arctic Ocean during winter breaks up in the summer and a 

 certain amount escapes into the North Atlantic Ocean. At the maxi- 

 mum of a glacial epoch when the coasts around the Arctic Ocean were 

 under ice, there would be a great flow of ice throughout the year into 

 the sea. The whole Arctic Ocean would become packed with ice which 

 would have to find an outlet somewhere. The Bering Strait between 



