EVIDENCE FROM ALASKA 43 



the ice has swept, diminutive lakes occur. . . . They occupy small depressions 

 or basins on the tops of these ridges. . . . They are all very small, only a few 

 yards in diameter and with no great depth. Some of them clearly occupy rock 

 basins. . . . The conclusion can not be avoided that these hollows were the 

 work of ice. In most cases the method of their formation seems clear." . . . 

 (Page 227.) "All these basins which I saw lie in small valleys on the mountain 

 tops, whose presence seemed to depend on the fissure systems and on the varying 

 depths to which loosening of the blocks had taken place. They lie at the foot of 

 slopes, down which the ice moved, impinging with unusual force at its base, where 

 the greatest amount of polishing and striating has taken place." (Page 230.) 



" The rough edges have uniformly been somewhat smoothed, but the character 

 of the surfaces seem to me to clearly show that the valleys and the basins have 

 been formed by the removal of loosened blocks, leaving a rough, jagged surface, 

 whose edges have been smoothed and polished." (Page 227.) 



4< Old surface features not obliterated. — On the mountains in Muir Glacier basin 

 from which the ice has recently retreated, surface features are occasionally observ- 

 able which seem incompatible with the theory that glaciers vigorously erode hard 

 rock. . . . That the glacier has done little more than to remove the loosened 

 rock and polish the resulting surface is shown in a vast number of localities here 

 by the character of that surface." (Pages 228, 229.) 



The existence of numerous islands in Muir inlet and Glacier bay is 

 conclusive proof that this fiord was not made by glacial erosion (see 

 Cushing's paper, page 227). His comments concerning the wash from 

 the glacier confirm the statement made on page 21 of this paper to the 

 effect that such estimates of the abrading power of the ice were value- 

 less. He says : 



" Estimates of the amount of material brought down by the glacier are difficult 

 to obtain owing to the fact that the material is all carried into the sea; that the 

 number of subglacial streams is not known; and that there is no evidence that 

 those which issue from the ice directly into the water carry as much sediment as 

 those which issue from the corners and flow through the gravels. I could find no 

 evidence inconsistent with the supposition that the debris falling on the surface of 

 the ice yearly, together with the previously disintegrated material which the ice has 

 removed and is removing, is amply sufficient to account for all the detritus depos- 

 ited at the front of the glacier. The amount of material in sight on the surface of 

 the glacier is enormous." (Page 229.) 



Doctor Gilbert's recent work on Alaskan glaciers* regards hanging 

 valleys as proof of the glacial origin of the Alaskan fiords. The com- 

 petency of Pleistocene glaciers to excavate one or two thousand feet in 

 crystalline rock is assumed. If such explanation were correct, then it 

 should harmonize with all other geologic facts of the region ; but it is 

 apparent that the phenomena are not in accord under this hypothesis, 

 for with his characteristic fairness the author mentions inconsistencies 



*G. K. Gilbert: " Harriman Alaska Expedition, III, Glaciers," 1904. 



