68 



NEW YORK STATE MUSEUM 



A peculiarity of the strongest bars which belong to the phase of 

 the falling waters is their direction transverse to the shore. Exam- 

 ples are Cooper ridge at Hamburg, the ridges at Eden and North 

 Evans, as well as the Dana ridge at Evans. Instead of being 

 parallel to the shore like normal shore bars they are directed into 

 the lake, and decline in hight. The mechanics of the constructional 

 operation is not clear, but the peculiar result in the bar form is 

 evident. 



It is again pertinent to repeat that the Whittlesey shore has 

 practically no inferior bars, yet the lake was a large water body 

 with twice the area of the present Erie, and the broad surface could 

 not have lowered suddenly. 



The objections to formation of bars at lower levels by falling 

 waters does not apply with force to extremely slow subsidence, and 

 it seems likely that such a series as the Warren bars, strong and 

 irregularly spaced, might well be produced by the very slow falling 

 of the surface due to the down cutting of the lake outlet, or to the 

 extremely slow tilting of the land due to unequal uplift. This will be 

 discussed later. 



2 The splitting of the bars, with increasing vertical spacing, due 

 to differential uplift or tilting of the land during the life of the lake 

 is theoretically probable. The New York area lies north of the 

 isobase or line of equal tilting drawn through the Warren outlet in 

 Michigan, and any-northward uplift or canting of the land during 

 the existence of the lake should produce a separation of the beaches. 

 With such origin the series of bars should manifest some divergence 

 among themselves, or a range of vertical spacing increasing north- 

 ward. Such is not readily apparent, for the vertical relation of 

 the Whittlesey and Warren bars remains nearly the same through 

 the 75 miles of shore line, though in that distance the whole double 

 shore rises 122 feet. However, there are complexities in the study 

 of shore deformation and bar divergence, and a small amount of 

 divergence in spacing would be difficult to measure. 



The diagram [fig. 4] is intended to indicate some of the difficulties 

 in the study of deformation of shores formed in front of receding 

 ice margins. Leverett has shown that west of New York the 

 deformation of the shores is very slight. In New York there is an 

 increasing deformation [see p. 77] as we pass northeastward, so 

 that the uplift toward the termination of the Whittlesey beach at 

 Marilla is 2 feet a mile. Taylor has concluded from a stud)' of the 

 features in the critical district of the Whittlesey outlet that the 

 Whittlesey beach was produced in slowly rising waters. If this is the 

 fact it would neutralize the effects of slight land warping. 



