BABBIT VALLEY. 277 



side the valley is girt about by imposing masses; on the north and west 

 by the slopes of the Awapa, and on the south by the Aquarius. Its floor 

 is a broad alluvial plain, receiving the wash of all the surrounding uplifts, 

 and carrying a noble stream, which is fed from all directions by rivulets 

 which have brought down their loads of debris and, reaching the nearly 

 level bottom, have deposited it. Those coming from the Awapa are always 

 dry in summer, excepting one which heads near the foot of the slope, but 

 the other tributaries from the north and south are perennial. The accumu- 

 lation of detritus through the ages has produced a broad expanse of alluvial 

 plain through which the Fremont River meanders, and nothing but a moist 

 atmosphere is wanting to make this valley an Eden. 



It is somewhat unusual to find so large an area in this elevated region 

 in which the accumulation is in excess of the power of the rivers to cany 

 it away. But this exceptional condition appears to have prevailed in 

 Rabbit Valley for a considerable time. It was apparently brought about 

 by the last stage in the uplifting to the eastward across the great fault, or, 

 what is the same thing, the downthrow of the valley itself; for these 

 vertical movements must be considered in a purely relative sense and as 

 meaning simply the difference of elevation between the lifted and thrown 

 sides, respectively, of the displacement. The Thousand Lake fault cuts 

 across the outlet of Rabbit Valley, which passes between Thousand Lake 

 Mountain and the northern salient of the Aquarius, and it has had the effect 

 of an increasing barrier to the outflow of the Fremont River and has 

 slackened its waters within the valley. Hence the loads of ditritus which 

 its affluents bring down from the plateaus on every side are thrown down 

 in the valley. Since the last paroxysm of uplifting the river has taken to 

 meandering, in consequence of the progressive building up of its channel 

 and has repeatedly shifted its bed over different parts of its flood plain. Old 

 canons in the borders of the lava sheets coming down from the Awapa have 

 been partially filled up and the river has abandoned them. In truth, a cor- 

 siderible number of low canons of this sort are still discernible in the lower 

 portions of these old trachy tic beds, and it is apparent at a glance that they 

 have nothing in common with the canons and ravines which descend the 

 slopes of that plateau, except to form the old trunk channel into which the 



