326 F. Carney — Wave-out Terraces in Keuka Valley. 



existed in this region in front of the advancing Wisconsin ice. 

 nor to those which on a priori grounds probably existed in 

 connection with both the retreat and advance of preceding 

 ice-sheets. There is very slight reason for thinking that the 

 topographic relations of the lowland area north from the 

 Niagara escarpment and the Allegheny plateau section of cen- 

 tral and western New York have changed much since the 

 beginning of the Pleistocene period. Such being the case, 

 then the duration of the pre- Wisconsin ice-dammed lakes deter- 

 mined the emphasis of the shore phenomena attained. Exist- 

 ing evidence of these old shore lines must, in most cases, stand 

 for sharp initial development, as the vigorous Wisconsin ice 

 with its great amount of debris tended to obliterate snch minor 

 details of pre-Wisconsin topography. 



Landwarping. 



Geologists early recognized the proof of instability in the 

 altitude of land areas. It was further recognized that the 

 range of vertical variation is not constant for any great hori- 

 zontal distance. The Great Lakes area has already been shown 

 to be rich in the evidence of such deformations. 



That the oscillations in the altitude of northeastern North 

 America incident to the late Wisconsin* stage and the suc- 

 ceeding stage of the Hochelagan formation! represent the 

 entire range of such variations during the Pleistocene period 

 is not necessarily true. With marine fossils in clays and sanely 

 clays 540 to 560 feet above present sea-level,;}: and stream-cut 

 channels at least 630 feet below present sea-level,§ we have an 

 interval of altitude that probably dates from the earliest ice- 

 epoch or even earlier. The surprising erosion in the Seneca 

 Lake Valley at Watkins, N. Y., reported by Tarr, has increased 

 significance when connected with the deductions made by 

 Fairchild concerning the ancient valley that leads into the 

 Sodus Bay arm of Lake Ontario. | These deeply buried val- 

 leys far inland, and mature but riverless valleys seaward, sug- 

 gest landwarping of like nature, but of far greater antiquity 

 than that proved in the investigations of the Iroquois beach. 



The Alteration of Shore Lines by Later Lce-Lnvasions. 



Partial or complete effacement of the constructional and 

 destructional products of wave and current work in these pre- 



*DeGeer. Proc. Boston Soc. Nat. Hist., vol. xxv, pp. 454-477, 1892. 



f J. B. Woodworth, New York State Museum, Bulletin 84. p. 204, 1905. 



jj. B. Woodworth, ibid., pp. 215-216, 1905; ibid., Bulletin 83, pp. 46-50, 

 1905. 



§E. S. Tarr, American Geologist, vol. xxxiii, p. 277, 1904. Professor Tan- 

 reports a well boring at Watkins, N. Y. , 1080 feet deep without reaching 

 rock. 



|| Bulletin Geol. Soc. Ami., vol. xvi. pp. 70-71. 1905. 



