Vol. i] Smith. — Upper Region of Main Walker River. 



13 



the present topography were it not that the direction of subse- 

 quent faulting coincided with it very closely ; thus, following the 

 establishment of the Bedrock Complex, there apparently inter- 

 vened a considerable period of erosion which wore it down to a 

 low relief. 



The Tertiary. — The dip of the Tertiary beds is about forty 

 degrees to the west, and they present a series of monoclines, and 

 the apparently plain-like surface on which the rhyolite rests is 

 also similarly inclined. The dip of it and that of the beds is 

 nearly the same. There are some bands of stratification in the 

 tuff lying under the later andesite cap, but their tilting is some- 

 what less. The altitudes are in striking contrast to the vertically 

 of the schists of the underlying Bedrock Complex. These schists, 

 moreover, strike northwest and southeast. The region is divided 

 by parallel ridges, which may be classed in two systems — those 

 trending northerly and somewhat westerly, and those approxi- 

 mately at right angles to these. The westward alluvium slopes 

 are many times longer than the eastward slopes, and the crest 

 of each system of ridges pitches toward the base of the other : 

 for example, the pitch of the third ridge shown along the east 

 margin of PI. 1 pitches north to the base of Cleaver Mountain, 

 which is just north, off the map, and it trends nearly east and 

 west. By pitch is meant the slope of crest-line. The pitch of 

 that mountain is also westward toward the base of Sing-ats'-e 

 Ridge. The crest of this last ridge pitches northward toward 

 the base of Cleaver Mountain, but the pitch is not as great as 

 in the case of the other north-south ridge, which, as may be seen 

 on the map, is broken into several buttes at its northern end. 

 The degrees of these respective pitches seems to be nearly pro- 

 portional, for the highest point, Cleaver Peak, is in line with the 

 chain of buttes. Some notion of these relations may be obtained 

 by consulting the Wabuska sheet and Fig. 1 ; and, as to the 

 general block tilting of the Cleaver Range both parallel to its 

 trend and transversely, an idea may be had by consulting the 

 earlier topographical map 1 of that range. This range is capped 

 with basalt, and it has been seen from two sides, so there may 

 not be great doubt as to the accuracy of the observation. This 

 1 Map No. 4S, Wheeler Survey West of 100th Meridian. 



