DAVIS: MOUNTAIN RANGES OF THE GREAT BASIN. Til 
Moreover, a mass of resistant rock could hardly be expected to be 
limited, except by a long block fault, so close to the line of the general 
mountain front; and it can hardly be a matter of chance that just 
where the general form of the mountain base suggests the most exten- 
sive subrecent faulting, there should occur the strongest recent fault as 
indicated by a broken gravel fan. Accepting then the conclusion that 
faulting is responsible for these basal bluffs, it may be noted that they 
are roughly in the stage of dissection indicated in Figure 6, except that 
all the edges are rounded off; but the initial upland of Figure 6 is here 
represented by the graded interstream surfaces that had been worn 
down to gentle slopes before the subrecent faulting began. There is 
some reason for associating this renewed uplift with the fault that has 
been above suggested to separate the southern and middle division of 
the range ; but more detailed field work is necessary on this point. 
The northern part of the middle Stein escarpment is breached by a 
large valley that comes southeast from the high Steins, and a small 
plateau-like block is thus cut off from the main mass as shown in 
Figure 14. Several low lava-bed monoclines, of gentle dip to the south- 
west, extend southeast from the detached block ; they gradually dip 
underground near the southern end of the Alvord desert (playa) and 
their trend very strongly suggests a tonnection with the monoclinal 
ridges of similar strike on the eastern side of the Alvord trough. It 
is certainly reasonable to infer a fault with downthrow on the southeast 
between these low lava monoclines and the high detached block that 
overlooks them. 
The Quaternary lake that Russell has described as occupying the 
Alvord trough left shore lines of moderate strength at various levels up 
to a few hundred feet over the present lake bed plain. The best ex- 
amples noted are seen on the low lava monoclines, just mentioned, 
where faint benches are developed; in the embayment of the main 
depression that heads between the low monoclines and the main escarp- 
ment of the middle Stein plateau, where two cross-bay bars were built 
to a height of 10 or 20 feet, about a mile north of Andrews; beneath 
the strong bluffs just north of Hollis’s ranch, where shore lines are 
associated with the chief fan delta of that district ; and near the north 
end of the Pueblo range, between Doane’s and Catlow’s, where what 
seems to be a long spit was built out into the lake from the bend in 
the mountain front near the beginning of the re-entrant between the 
Pueblo and the Stein ranges. 
To any one who wishes to give a month to the study of a well-defined 
