The Idea of Glacial Erosion in America 201 
1878 — CLARENCE KING. 
One of King’s conclusions from his study of glaciation in the Cor- 
dillferan section of the Fortieth Parallel Survey is the following: 
“There is not a particle of direct evidence, so far as I can see, to 
warrant the belief that these U-shaped canons were given their 
peculiar form by other means than the actual ploughing erosion 
of glaciers; nor do the objections to this belief advanced by cer- 
tain observers, based upon the moderate amount of detritus trans- 
ported by the existing glacier-streams of the Alps, seem to be 
worthy of serious consideration, since the Alpine glaciers of the 
present day are at the best but the shrunken relics of the former 
system; and with vastly greater accumulation of snow in the ice 
period there is every reason to believe that the thickness, move- 
ment, and energy of the glacier must have been much greater, and 
that its power of abrasion would be correspondingly increased. 
1882 — W. M. DAVIS. 
In connection with Davis’s arrangement of the evidence for and 
against glacial erosion, he makes the following comments: “It 
must be granted that the ice itself will suffer when pressed on its 
bed, and in spite of its long action will fail to produce much erosive 
change. 
“No sufficient reason has been given to show why the glaciers 
of the Italian slope of the Alps should be suddenly endowed near 
their ends with erosive power sufficient to cut out lakes 1000 to 
2000 feet deep, while a little farther up stream their valleys were 
but slightly modified, as Ramsey himself claims.”® 
Professor Davis has since studied one of these valleys, and 
became convinced that ice had modified it; his discussion of ice- 
erosion in the Ticino valley, to be referred to later, is one of the 
great contributions to the subject.^® 
’ Loc. cii., p. 483. 
® Proceedings of the Boston Society of Natural History, voL xxii, p. 28. 
« Ihid., p. 53-54. 
Appalachia, “Glacial Erosion in the Valley of the Ticino,” vol. ix, pp. 136-56, 
1900. 
