314 American Geologist, ^^*y' ^^^^ 
been voiced by Tarr,* Fairchild.f and Russell,^ with whom I 
confidently concur. In numerous places where glaciation had 
been supposed to account for the over-deepening of the trunk 
valleys, it is shown by these writers that insuperable objec- 
tions oppose such an explanation, that the ice-erosion was of 
small amount in comparison with river sculpture and weath- 
ering, and that similar relations of cafions and hanging val- 
leys occur in regions which have had no glaciation. 
Epeirogenic uplifting of great areas, comprising large parts 
of continents, rejuvenating the principal streams so that they 
cut down their channels rapidly, while the little tributaries 
lagged in their downward channeling, seems to me the general 
and acceptable explanation of the very deep valleys, canons, 
and fjords with their lateral hanging valleys. 
No more certain conclusion in the science of geology has 
been attained than the uniqueness of the Ice age. For this 
period of quite unusual and unexampled conditions in climate 
and snow and ice accumulation, some equally extraordinary 
causes must be sought. It is found, as I believe, in the epeir- 
ogenic elevation of the areas that were glaciated. The meas- 
ure of their uplift, or a part of it , is supplied by the depths of 
the fjords, which cannot, as I think, be logically referred to ice- 
erosion, but must instead, be due to river-channeling. They 
show, according to this view, that the glaciated lands had been 
raised thousands of feet higher than now, until their elevation 
brought a cold and snowy climate. While they were being up- 
lifted, and during the early part of their elevation, the large 
rivers cut down rapidly and deeply, but the small brooks and 
rills wore very little and remained in hanging valleys, an ano- 
maly and puzzle for geologists. > 
With ice envelopment of these areas, the valleys were mod- 
erately glaciated, their sides being much smoothed, but prob- 
ably receiving little or no addition to their depth. Finallv, un- 
♦Ralph S. Tarr, "Hanging Valleys in the Finger Lake Region of Cen- 
tral New York," American Geologist, toI. xxxlii, pp. 271-291, May, 1904. 
"The Gorges and Waterfalls of Central New York," Bulletin of the American 
Geographical Society, vol. xxxvii, pp. 193-212, April, 1905. Professor Tarr, 
ten years before, had attributed Lake Cayuga and others of the Finger 
lakes to glacial erosion, on the evidence of their high lateral tributaries 
(Bulletin, Geological Society of America, vol. v, pp. 339-356) ; and his latest 
testimony in favor of stream erosion as probably the chief agency in the 
channeling of these remarkable lake basins is thus his more mature conclu- 
Elon. 
tH. L. Falrchild, "Ice Erosion Theory a Fallacy," Bulletin, Geological 
Society of America, vol. xvl, pp. 13-74, February, 1905. 
tisrael C. Russell, "Hanging Valleys."' Bulletin, Geological Society of 
America, vol. xvl, pp. 75-90, February, 1905. 
