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



maximum inclination is usually near the water surface, and for a hundred feet or 

 so may locally approach 60 degrees. Generally it is less than 40 degrees. And 

 from this steepest facet the profiles rise in a curve which is convex upward, and 

 pass into the nearly level spurs of the adjacent ranges." (Page 59.) 



Questioning the amount of glaciation in the general region and on 

 other valleys, the author admits that the valleys are preglacial and have 

 only been modified, and that the Chelan valley is peculiar. Following- 

 are the words : . 



11 In the glaciated region of the higher Cascades, the canyons are developed on 

 a grand scale. Russell has rightly described them as extending with channels at 

 railroad grades into the very heart of the mountain mass, and they are from 1,000 

 to 3,000 feet in depth. They have been widened and deepened by ice-work, to 

 what degree is not to be determined, but apparently in some instances greatly. 

 Nevertheless, when all reasonable allowance has been made for glaciation, the 

 canyons which may be ascribed to corrasion during the Twisp stage (preglacial) 

 were of great depth. They were relatively narrower than they now are, and their 

 topographic development had the character of advanced youth." (Page 81.) 



"A further test of this conclusion (ice deepening) may be applied by contrasting 

 it with other valleys in the same region, many of which have been occupied by 

 glaciers, and none of which exhibit similar peculiarities." (Page 83.) 



Plate 16, reproduced from Willis 1 paper, shows the cross-profile and 

 the proportions of the valley at " The Narrows," the narrowest part of 

 the gorge, which is also the deepest part of the lake. This shows that 

 the valley is decidedly V-shaped in the deep section, and the profile 

 of the walls convex when the submerged section is included. These 

 are the opposite of glacial characters. The gorge here shows no lateral 

 erosion, although glacial widening is claimed for other valleys of the 

 region. It is also admitted that no other valleys of the region exhibit 

 the peculiar features of the Chelan gorge, the suggested explanation 

 being the greater volume of the Chelan glacier. 



From the published facts, mostly quoted above, we are unable to 

 find any evidence whatever of ice erosion in the Chelan gorge. All our 

 knowledge of glacier work opposes the idea. Where are the concave 

 profiles and U shape, recognized as special characters of valley erosion 

 by glaciers, and where is the enormous mass of clayey moraine which 

 should have been produced by such vast abrasion ? No description is 

 given of the drift. It is inconceivable that a glacier should deepen a 

 narrow gorge 1,000 feet and yet produce no perceptible cutting of the 

 valley walls. The walls at the narrows were the obstruction which 

 would have been cut away. 



The fact of the depth of the gorge being inversely proportioned to the 

 width has been suggestively explained as an effect of increased velocity 

 in the narrow section, citing the behavior of rivers. The comparison 



