DAVIS: MOUNTAIN RANGES OF THE GREAT BASIN. 149 
base and its canyons testify in favor of block faulting. The next follow- 
ing paragraphs therefore attempt to discover the forms that should char- 
acterize the ideal case of a faulted block of homogeneous structure whose 
faulting has progressed at a slow and relatively uniform rate, so that the 
sides of the ravines that are eroded in it shall be weathered back to 
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, 2 e 
rs ~~ 
FiGure 7. 
Diagram showing notches in the front of a young tilted block, more uplifted than in Fig. 6; 
nothing of the front edge now remains. 
graded slopes about as fast as the fault block is raised. Three significant 
stages of faulting and erosion may be considered. In an early stage, 
Figure 6, the low fault scarp is notched by ravines whose location and 
length are determined by the site of prefaulting inequalities in the 
upper surface of the block. Adjacent ravines have not yet widened suf- 
ficiently to consume the edge at the top of the block between them. In 
a later stage, Figure 7, the block is raised higher, the ravines are worn 
deeper and further back, some of them being larger than others. Noth- 
