DAVIS: THE WASATCH, CANYON, AND HOUSE RANGES. 25 
The open valley or basin that we followed southward from Santaquin 
to Nephi was bounded on the west by a low range of subdued form, 
Whose eastward slope had many sprawling spurs that gradually melted 
away in the piedmont plain. Isolated hills sometimes rose from the 
plain farther forward than the spur ends. The piedmont wash headed 
in open valleys of gentle grade, interlocking with the low sprawling 
Spurs. Spurs and valleys blended together almost too delicately to be 
shown properly in an outline sketch, but their relation may perhaps be 
Suggested in figure 9, drawn from parts of the range west of Nephi. 
Fra. 9.— Diagram of graded spurs in a subdued range, west of Nephi. 
The recognition of these gentle features in the well dissected and sub- 
dued ranges, in contrast to the stronger and sharper elements of form 
in the higher ranges, is an important element in the discussion of the 
ranges of the Great basin. 
Different Types of Mountain Fronts. The peculiar features of the 
Wasatch front, as here described, may perhaps be better appreciated 
in their relation to the theory of fault-block mountains in general, if 
two examples of the forms of vigorous mountain fronts of other origin 
are adduced. 
A simple type of vigorous mountain front, in which structure and 
form are closely accordant, is found along the Rocky mountain border 
West of Denver. Here a broad uplift has brought the crystalline moun- 
tain core above the level of the horizontal strata of the Plains, the two 
being separated by a strong monoclinal flexure of the Palaeozoic and 
later strata, such as was long ago well shown in Holmes’s illustra- 
tions of Hayden’s early reports; for example in Section III, p. 31, of 
the Report for 1873. The mountain border does not, however, retain 
in any close way the form initially produced by deformation. Exten- 
sive erosion has worked upon the uplifted mass; the weaker strata of 
the Plains have been worn down to moderate relief, even to a pene- 
plain over large areas, and the mountains now rise only where the 
uplifted masses are composed of resistant rocks. The most impor- 
