34 H. L. FAIRCHILD — ICE EROSION THEORY A FALLACY 



dence. There is so much indefiniteness and genetic complexity in features 

 of topography that interpretation has unusual latitude. The attitude of 

 mind and the theory of the observer count for much more than in most 

 other lines of study, and the arguments, conclusions, and assertions are 

 often difficult to either verify or deny, although doubt may be very strong. 



Greenland. — During the past decade Greenland has been the Mecca of 

 the glacialists, and among those who have visited the land and published 

 their observations are Barton, Chamberlin, Heilprin, Nansen, Peary, 

 Salisbury, Tarr, and Wright. The writings of all these men practically 

 agree on the following points: That the West Greenland glaciers are 

 carrying but little drift, and that mainly in the basal layers ; that ero- 

 sion is slight; that the exposed topographic features are not the product 

 of ice erosion; that the lower layers of the ice show reduced movement, 

 with some shearing of upper over subjacent layers; the overriding of 

 boulders and other obstructions ; the overriding by the edge of the ice 

 of its own moraine deposits ; and the comparative absence of clay or 

 rock-flour. 



It will not be necessary to refer at length to the literature * as fortu- 

 nately there is no essential divergence of opinion over the fact of slight 

 ice erosion. 



More than any other writer on the Greenland glaciers, Professor Tarr 

 has referred to the erosional phenomena, and has particularly and em- 

 phatically noted the failure of the ice in that respect. This is the more 

 significant as Professor Tarr has been one of the American advocates of 

 ice-eroded valleys. A few lines quoted from his writings will be per- 

 tinent. 



"Although the hills of Turnavik (eastern margin of Labrador) are well rounded, 

 and show signs of decided ice scouring, . . . it is evident that the glaciation 

 did not succeed in destroying even the details of the preglacial topography. . . . 

 This evidence of slight scouring is in harmony with that found in Baffin land and 

 Greenland, and also in parts of New England. It shows that preglacial decay was 

 deep, and that the general ice scouring did not lower the surface far below the zone 

 of decay in the weaker members of the rock series." (Am. Geol., xix, 192.) 



" Very nearly the same conditions were present in Cumberland sound, though 

 the details of the preglacial topography are perhaps even more perfectly preserved. 

 The surface of the hills is extremely irregular, and valleys and ridges of minute 

 size, distinctly of preglacial origin, abound. ... It was astonishing to find how 

 little effect in smoothing the surface was accomplished by the ice invasion of the 



*The writings of Professor Chamberlin are to be found in a series of articles in the Journal of 

 Geology, vols, ii, iii, and iv, and in the Bull. Geol. Soc. Am., vol. 6, pp. 199-220. 



R. D. Salisbury: Jour. Geol., vol. iii, pp. 875-902; vol. iv, pp. 769-810. 



G. H. Barton : Tech. Quart., vol. x, pp. 213-244. 



R. S. Tarr : Amer. Geol., vol. 19, pp. 131-136, 191-197, 262-267 ; vol. 20, pp. 139-156. Bull. Geol. Soc. 

 Am., vol. 8, pp. 251-268. 



A. Heilprin : Pop. Sci. Monthly, vol. 46, pp. 1-14. 



