THE CHAMPLAIN SEA IN THE LAKE ONTARIO BASIN 551 



thickness of the ice cap were made with the expressed purpose 1 of 

 determining the "maximum upheaval of the water" possible as a 

 result of glacial conditions. I have, therefore, with indispensable 

 assistance from my wife, computed the results obtained from his 

 formulas on the basis of quite different assumptions, which are 

 believed to be more in accord with known data concerning the 

 Labradorian ice sheet. 



For mathematical purposes it is fair to assume a circular ice 

 cap with a radius of 14 , or about 966 miles, on the earth's surface 

 and a thickness at its center of 5,000 feet. Let its surface configura- 

 tion correspond to n= 10 in Woodward's equation Q5. 2 This would 

 give an increasingly rapid slope of the ice surface from center to 

 border as in the following table: 



From equation 96 it follows that such an ice cap would lower 

 the sea-level 82.5 feet, if all its ice were formed from moisture 

 withdrawn from the ocean. Following the method of Woodward in 

 § 49, 3 we find that the gravitative attraction of this ice sheet would 

 distort the level of the sea so that the disturbed surface along the 

 border of the ice mass would be 136 feet above the undisturbed 

 surface. The average slope of the disturbed surface within one 

 degree of the ice border would be 0.13 feet per mile. If the ice 

 cap were 10,000 feet in thickness at its center, the distortional effect 

 would be twice as great as that of a 5,000-foot cap of the same 

 diameter and surface contour. 



There is every reason for believing that the development of 

 the half-dozen ice sheets which covered parts of North America 

 and Europe in Pleistocene times was practically synchronous. 

 The total effect of all must, therefore, be considered in evaluating 



1 Ibid., p. 18. 



2 Ibid., p. 62. 



3 Ibid., pp. 65-f; 



