DAVIS: THE WASATCH, CANYON, AND HOUSE RANGES. 49 
concerned. The uplifted block has, as a natural accompaniment, an 
associated depressed block, now buried under the detritus of the 
adjacent intermont trough. The trough or basin of Tule flats, 
west of the House range, is an excellent counterpart of the range itself. 
The amount of displacement by which the House range block was 
Set in relief is not closely determinate, because the corresponding strata 
in the depressed block under Tule flats are not to be seen; but a meas- 
ure of 3,000 feet may be given as a minimum. 
Post-faulting Erosion of the House Range. The erosion that the 
House range has suffered since the last faulting and uplift of its block 
is very much greater than the corresponding erosion of the Wasatch 
range. The base of the House range escarpment is not marked by 
any faults across its detrital fans. The great promontories and spurs 
into which the face of the Swazy escarpment in particular is carved 
have no distinct truncating facets at their base. The crest of the 
escarpment in general must have retreated the greater part of a mile 
from the fault face. The valleys between the spurs have somewhat 
Opened mouths. The back slopes of the Swazy and Sawtooth masses 
are deeply carved by many valleys. If the range shows more un- 
graded cliffs than are seen in the Spanish-peak Wasatch, for example, 
this feature must be ascribed to the repeated alternations of hard and 
soft layers, and not to early youth. Yet the erosion of the faulted 
Mass must reach at least twice its present large measure before the 
evidence of faulting, based on the oblique truncation of the heavy 
limestones by the west-facing escarpment, is seriously impaired. 
An appropriate consequence of the advanced erosion of the uplifted 
block is the great size of the fans at the foot of the escarpment. It is 
evident enough from the small share that the Bonneville waves have 
had in modifying the fans that the climatic conditions which led to the 
formation of large lakes in the intermont depressions were brief and 
recent episodes in the post-faulting history of the range, and that a 
Climate like that of today has been characteristic of the region as far 
back as climatic conditions can be inferred. 
_ Pre-jaulting Erosion of the House Range. An interesting problem 
IS opened by the search for remains of forms that were produced by 
€rosion in the pre-faulting cycle and that have not yet been entirely 
obliterated by the erosion of the post-faulting cycle. It is evident that 
Such forms are limited to the back slope of the tilted block. They had 
their origin in the first of the three chapters into which any problem of 
the kind here treated is naturally divided: a first cycle of erosion, 
Involving the structure, erosion and form of the pre-faulting period; 
