DISCUSSION AS TO ORIGIN 83 



glacial erosion, while the other implies far less conspicuous results in 

 this connection. In looking for criteria by which to test the two hy- 

 potheses there are evidently two chief directions in which search may 

 reasonably be expected to yield assistance. These are, first, the topo- 

 graphic features due to removal of material in order to produce the 

 valleys of glaciated mountains, and, second, the character, and espe- 

 cially the amount of material still in sight and recognizable, which was 

 removed by glaciers and deposited elsewhere. 



If the mountains in which hanging valleys are a common feature, owe 

 the valleys — the excavations of which have given them their leading and 

 characteristic features — wholly or to a conspicuously great degree to glacial 

 erosion, or, on the other hand, have been shaped principally by stream 

 erosion and only to a minor degree modified by glaciers, the study of 

 the character, distribution, and interrelation of their valleys furnishes a 

 basis for opinion. 



I must freely confess that I am not in a position to thoroughly discuss 

 this broad and far-reaching problem, but venture to direct attention to 

 two localities which seem to furnish data bearing on the question im- 

 mediately before us. 



Throughout the major portions of the Sierra Nevada and Cascade 

 range there are conspicuous evidences of erosion both by water and ice ; 

 but to the direct question : Did pronounced stream erosion precede the 

 work of the glaciers ? It is difficult with the criteria at present avail- 

 able to obtain a satisfactory answer. The conditions demanding con- 

 sideration are complex, and the decidedly vigorous ice erosion which 

 has occurred in many portions of the mountains referred to did much to 

 erase the evidence pertaining to the nature of the pre-Glacial topography. 

 Better localities for beginning the inquiry under consideration are, in 

 my judgment, furnished by the mountains of the Great basin which 

 bear records of a brief period of glaciation on their higher portions. 

 For this purpose Stein mountain, in southeastern Oregon, is well suited. 



DETAILED STUDY OF KIEQER CREEK CANYON AS A TYPE 



Stein mountain* is a typical block mountain, with a bold eastern 

 face, bordering a fault or a series of faults, and is inclined gently west- 

 ward. Its elevation is about 9,000 feet, and it rises approximately 5,000 

 feet above the basin at its eastern base. Starting at the crest of the tilted 

 block and leading westward are several deep canyons, one of which, 

 Kieger Creek canyon, contains unmistakable evidence of glaciation in 



*The facts here presented in reference to Stein mountain are from Bull. no. 217, U. S. Geol, 

 Survey, pp. 16-17. 



XII— Bull. Geol. Soc. Am., Vol. 16, 1904 



