36 THE JOURNAL OF GEOLOGY. 



the slope of the Sierra is — in the mining region at least — -quite 

 moderate, for if we allow a rise of 7,000 feet from the lower edge 

 of the foothills to the crest of the range, the distance between 

 the two points being about seventy miles, the average rise is only 

 100 feet to the mile, which gives an angle of slope of less than 

 two degrees. And if one ascends the Sierra, keeping on the 

 divide between any two rivers in the mining districts, he will find 

 himself, for most of the time at least, on what seems to be a 

 plain with a very gentle rise. Let the traveler, however, turn 

 and attempt to make his way across the country, in a line par- 

 allel with the crest of the range, and he will discover that this 

 apparent plain is cut into by the gorges or cafions in which the 

 present rivers run, in a most extraordinary manner ; he will find 

 it several hours' work to descend into one of these and rise again 

 to the general level on the other side, even if assisted by a well- 

 beaten trail. All along the western slope of the Sierra the streams 

 have worn for themselves deep canons, and it is these tremendous 

 gorges which form the leading feature of the topography of the 

 region. If the streams ran nearly on a level with the general 

 elevation of the surface, the whole character of the mountain 

 slope would be changed. This was formerly the condition of 

 the drainage of the Sierra slope."' Concerning the topography 

 of the same region, Mr. Ross E. Browne remarks that "at cer- 

 tain favorably located points an extended view is obtained of the 

 Forest Hill and neighboring divides. Upon losing the effect of 

 the detail, one receives the impression of a general uniformity in 

 the grades of the summit-lines. These summit-lines appear as 

 the remaining traces of a gently undulating plain, sloping regu- 

 larly from the bases of the massive peaks of the Sierra to the 

 Sacramento valley."^ Extended views of the western slope of 

 the Sierra Nevada may be obtained at many points from the 

 Central Pacific railroad between Colfax and the summit, and they 

 fully illustrate the feature referred to. 



' Auriferous Gravels of the Sierra Nevada of California, by J. D. Whitney. Pp. 

 63-64. 



^The Ancient River Beds of the Forest Hill Divide. Tenth Annual Report of the 

 State Mineralogist of California, 1890, p. 435. 



