CHECKS AND PROOFS 249 



ing these figures. It is believed that the data given in the table harmonize 

 the field data and clarify our knowledge of the Pleistocene water planes 

 in New York, and that further study in the areas not yet mapped will 

 confirm these figures. 



One of the most significant proofs of the correctness of the philosophy 

 of this paper is the remarkable coincidence of the derived figures for the 

 amount of Glacial time uplift north of the fulcral line with the actual 

 amount as indicated by the bar spacing found in the field. This is de- 

 scribed in the next chapter. 



Relation- of Land Uplift to the Ice Body 



The broad relationship of the Labradorian glacier, in both extent and 

 thickness, to the area and the amount of Pleistocene uplift of the land 

 has long been recognized. The results of the present study, specially 

 shown in the tabulated data, strikingly emphasize the causal relationship 

 of the weight of the ice-body to the land movement. 



In the previous chapter it was shown that the two points in the Iro- 

 quois area which were earliest relieved of the ice burden, Hamilton and 

 Rome, experienced the largest amount of uplift, relative to the total rise, 

 during Glacial (Iroquois) time, it being more than half. Passing north 

 from Rome, the amount of Glacial uplift decreases rapidly, and at Water- 

 town it is only one-seventh of the total. Farther north it decreases to 

 zero at Chateaugay and Covey outlet. These facts will be used later (see 

 pages 251-252). 



The beaches in Canada show similar relations. Toronto, on the same 

 isobase as Greece, with about the same relation to the ice-body, has sim- 

 ilar figures, the Glacial uplift being two-fifths of the total. But Quays, 

 on the same isobase as Rome, but much longer under the ice-body, received 

 less than one-fourth of its rise in Glacial time. The district north from 

 Quays shows declining Glacial rise and greater post-Glacial, similar to 

 northern New York. Some of these figures from Professor Coleman are 

 possibly subject to slight correction (95, page 356), but the significant 

 facts will stand. 



These facts are all in agreement with our knowledge of the form and 

 mass of the waning ice-sheet during its slow removal from New York. 

 An attempt to exhibit several phases in the ice removal has been made by 

 the writer in a series of maps (119, plates 34-42 ; 125, plates 9-17) . 



From the data already in hand it seems certain that the Iroquois basin 

 was not lifted as a rigid mass, but by a wave movement. The south side 

 of the basin was given (on the average) only one-half of its total rise 

 during Iroquois time. The northern portion was lifted very little, and 

 the far north portion not at all, until Gilbert Gulf and later time. 

 XIX — Bull. Geol. Soc. Am., Vol. 27, X915 



