GLACIAL WATERS IN THE LAKE ERIE BASIN 



69 



West of the Marilla-Alden district the Warren 

 bars were not formed at the ice front but were 

 produced synchronously throughout the entire 

 extent by the falhng from the Whittlesey level. 

 These bars should be continuous and should re- 

 cord among themselves all the divergence due to 

 land tilting, but this effect is so small in the area 

 of New York that it must be obscured by the 

 constructional irregularity of the bars. 



East of the Marilla district the Warren waters 

 laved the ice front and from there eastward the 

 bars should have the fragmentaj character due 

 to a shore line extending toward receding ice 

 while the land was tilting. But here the life of. 

 the lake was briefer and eastward the bars are 

 not sufTficiently developed to yield an}^ reliable 

 data. 



The diagram shows that the bars formed in 

 front of the receding ice margin are theoretically 

 not continuous or in the same plane, but that 

 they represent successively lower planes. Con- 

 sequently our measure of deformation on such 

 shores fails to show the full amount. 



The above may give some idea of the 

 quantitative difficulty in the study. The series 

 of Whittlesey-Warren bars seem to retain a 

 practically uniform relation and it seems quite 

 certain that most of the land tilting which has 

 occurred took place subsequent to Warren time. 

 Nevertheless it seems probable that a small 

 amount of deformation which may have taken 

 place during Warren time helped to produce the 

 multiplicity of bars and the large vertical 

 spacing in New York. 



3 The conception of a second water level was 

 the very natural explanation of the considerable 

 vertical range of the Warren bars, specially as 

 in some localities only two conspicuous ridges 

 are found. Objections to this explanation are 

 the decided lack of uniformity in relative 

 position of the lower bars, and the equalh'- de- 



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