No. 3. — The Mountain Ranges of the Great Basin. 
By W. M. Davis. 
TABLE OF CONTENTS. 
PAGE PAGE 
Historical Statement - .. . . 129|The Mountain Face <:... . 148 
Theoretical Considerations . . 131 | Spurs and Terminal Facets of the 
Ideal Types of Fault-block Mioui! Wahsatch Range. . . 152 
fans? Wop =) . . 1382} The Spur-Facets are not Wave- Cut 155 
Place and Value of Tiedaction . . 155 |The Erosion of the Spur-Facets . 158 
Evidence of Faulting along the Other Parts of Block Mountains . 158 
Mountain Base. . 137 | Modern Faulting. . . : 160 
The Base Line of Residual ‘ater The Measure and Distribution of 
TADS a 140 Faulting .. . Bobs allen 
Residual Mguntains in the ‘Great The Pueblo-Stein Mountaiia. . . 164 
ASIN og 142|The Shoshone Range. . . . . 172 
The Canyons and ayes of Black Bibliography, sus. = 2 2 ee ie 
Miointain sie) weer eee-) 1on) 143) Pxplanationiof platesiz.02).) alcaG 
Historical Statement. — The larger mountain ranges of the Great Basin 
offer problems of especial interest, inasmuch as the faulting by which their 
present relief is believed to have been produced is not proved by strati- 
graphic evidence of the kind familiar to geologists, but by physiographic 
evidence of a kind to which little attention is usually given. These 
ranges were described by King in 1879 as “ordinarily the tops of folds 
whose deep synclinal valleys are filled with: Tertiary and Quaternary 
detritus ” (a, 451). Soon afterwards Gilbert concluded that the in- 
dividual ranges were the carved upper parts of tilted or lifted blocks, 
resulting from “ the displacement of comparatively rigid bodies of strata 
by vertical or nearly vertical faults” (1874, a, 50). The same view was 
elaborated in a later report (1875, b, 21-42). Powell, Dutton, and Rus- 
sell adopted essentially the same explanation. King also seems to have 
recognized the validity of Gilbert’s conclusion, for in 1878 he modified 
his earlier views by recognizing frequent faulting at a later date than that 
of the folding by which the great anticlinals and synclinals had been — 
produced (b, 735). None of these observers, however, gave explicit con- 
sideration to the three elements necessarily involved in the problem of 
block faulting; namely, the prefaulting topography, the topographic 
effect of the faulting, and the work of erosion on the faulted blocks. 
VOL. XLII. — NO. 3 
