Vol. 6] Eeid: The Geomorphogeny of the Sierra Nevada. 139 



not due to faulting, would show elsewhere, which is not the case. 

 The form of this terrace is very interesting, as outlined by the 

 5,000-feet contour. The embayment west of the gravel terrace 

 might be the result of stream erosion, but no streams other than 

 wet-weather ones flow there. Furthermore, the valley here con- 

 tains a good soil, with no gravel. At the fork in the road just 

 west of the summit of the terrace there is a distinct alluvial fan 

 whose apex lies above the slope leading down to the lower valley 

 to the west, and thus seems to be a beheaded fan. The faults in 

 the granite south of Clear Creek are evident, and their projection 

 into the valley coincides with the lines of the probable faulting 

 that produced the embayment west of the highest gravel terrace. 

 The projection of the fault-line that runs south from Carson lies 

 in the proper position to have formed the east side of the same 

 terrace. Hence for the present this hypothesis as to the mode of 

 formation of the terrace will be adopted. The formation of the 

 low divide south of Carson is due, then, to the uplift of the 

 bounding fault-blocks, which are here quite near. South of the 

 divide the valley is too wide to admit of equal elevation of the 

 whole valley floor, or the river would have been dammed and a 

 temporary lake formed. The crust blocks on both sides were ele- 

 vated, however, as already described on the west, and as shown 

 by an elevated line of sands similar to those on Prison Hill, on 

 the hill just south. 



From Clear Creek north to Washoe it is evident that a tilting 

 of the valley floor has taken place quite recently, and may even 

 yet be in progress. 



North of Washoe a line of narrow valleys forms a connection 

 to the Truckee Meadows, through which the Truckee River 

 flows eastward. From Reno westward a number of terraces of 

 this river occur. The highest slope upward to the west at an 

 angle greater than that of the river, while the lowest has the 

 grade of the river. Careful surveys can here establish the exact 

 amount of this eastward tilting. 



IMPOBTANT FEATUBES OF THE NEVADA BANGES. 

 There are a few characteristics of the ranges in Nevada that 

 call for description here, because of their close relationship to 

 the structural features already described. In the east part of 



