68 H. L. FAIRCHILD — GLACIAL WATERS IN FINGER LAKES REGION 



delta terraces. Altitudes of water-planes based on such phenomena con- 

 tain an element of error, the uncertainty of the vertical relation of l)ars 

 and S])its to the water surface. In the long stretches of shorelines about 

 the great lake basins this error may be neglected, but it becomes serious 

 in the short distances here available. The Watkins-Newberry plienomena 

 have also another factor of error. The down-cutting of the Horseheads 

 outlet caused a lowering of the water-level. As this was effected during 

 the retreat of the ice-front, it is expected that the higher Watkins-NcAV- 

 ben-y phenomena should decrease in original altitude toward the north, 

 and therefore would apparently decrease the effect of subsequent north- 

 ward land uplifting. This error does not pertain to the Warren phe- 

 nomena, and the latter have been most relied upon in estimating the 

 amount of deformation, although it has been found that the clearer New- 

 berry'- bars have in general about the same height above the Warren, 

 namely, 100 feet. 



In the Seneca valley the considerable number of accurately determined 

 elevations permit generalization regarding the north-and-south defor- 

 mation, notwithstanding the uncertainty in individual cases of the 

 vertical relation to the water-level. In the southern half of the Seneca 

 valle}^ the deformation of the Newberry and Warren levels is about 1.5 

 feet per mile north-and-south, but in the northern half of the same 

 valle}^ the Dana beaches on the west slope show a northward uplift of 3 

 feet per mile. 



It appears, therefore, that either tlie Seneca valley has suffered local 

 warping or that there is a northward increase of the amount of tilting 

 over the broader area. Both ma}^ be true, and the latter seems prob- 

 able, since Dr Gilbert finds that the deformation of the Iroquois beach 

 northward from Syracuse is 5 feet per mile. 



