12 NEW YORK STATE MUSEUM 



leys were far below sea level when the latest ice sheet withdrew. 

 The Iroquois shore line adds positive confirmation. 



The deformation or tilting is due to northward differential uplift. 

 It would only introduce complexity and unreason to assume that 

 the New York end of the shore line had subsided from some 

 higher position. And it must be admitted that the shore line, as a 

 consistent unit, representing a sinfii;le water body, was originally 

 horizontal. 



The accompanying maps and the diagram (plate lo) give the 

 main 'facts showing the uplift of the territory. It will be very 

 difficult to determine the point of no uplift, as the southern border 

 of the tilted area must grade imperceptibly into the unaffected 

 area. It is also recognized that minor positive and negative move- 

 ments, and perhaps some unknown factors, have possibly confused 

 the record. Where the old shore has an altitude less' than 20 or 30 

 feet the wave inscriptions are weak and equivocal. 



Some details regarding the character of the shore line and the 

 plotting of the line in plate 10 belong in a later chapter (page 23). 



4 Evidence of Uplift from Lake Iroquois 



Plates 4-7 



The Iroquois shore, taken by itself, clearly proves the large 

 uplift at Covey hill. In conjunction with the shore lines of the 

 higher and earlier glacial lakes it is positive that the deformation 

 is a northward uplift, in direction N 20° E. 



The Iroquois beach is now well known throughout the entire 

 basin, from Hamilton, Ontario, to the place of its extinction. It 

 is the clos ng level of a single water body. The beach rises from 

 362 feet at Hamilton to 1030 feet at the Covey outlet. This gives 

 a northward differential uplift at Covey outlet of 668 feet. The 

 north boundary of the State was therefore as much as 668 feet 

 lower than it is today at tlie time when Lake Iroquois was extin- 

 guished. And it was also as much lower than the 668 feet by 

 whatever amount Hamilton has risen since the death of Iroquois. 

 A glance at plate 9 shows that the total uplift at Hamilton in 

 Glacial time is 195 feet, which has been determined by the differ- 

 ential uplift of the glacial lake beaches earlier than Iroquois. The 

 tabulation of data, plate 12, makes the Post-Iroquois uplift at Ham- 

 ilton 72 feet. That is to say, that of the 195 feet rise at Hamilton 

 only ^^2 feet is needed to add to the ^^ feet at Covey in order to 

 make the 740 feet uplift shown by the marine shore. 



