268 J. E. SPURK — OKIGIN AND STRUCTURE OF THE BASIN RANGES 



Plate 23. — Effects of Faulting on Topography 



Figure 1. — ^ Faulting at Eureka, Nevada (after Ha^ue). 



From Monograph XX, U. S. Geological Survey, Atlas Sheet XIII. 

 Section CJ H. Shows ascendency of erosion over faulting, a, 

 slight erosion fault-gully ; 6, slight normal erosion fault-scarp ; 

 c, slight reversed erosion fault-scarp. Scale, 1 inch = about 1,350 

 feet. 



Figure 2. — Ideal result of ascendency of faulting over erosion (Spurr). 



Ideal figure to show what would have been the approxiuiate topog- 

 raphy of figure 1 had faulting outstripped erosion. Scale, 1 inch = 

 about 1,350 feet. 



Figure 3. — Faulting at Eureka, Nevada (after Hague). 



Also from Monograph XX, Atlas Sheet XIII. Section A B. Sliows 

 ascendency of erosion over faulting. Reversed erosion fault-scarp. 

 Scale, 1 inch ■= 1,350 feet. 



D^= Nevada limestone (Devonian) ; W. P. = White Pine shales (De- 

 vonian) ; L. C. = Lower Coal INIeasures strata. The foult shown in 

 tlu; section is a normal fault, having the downthrow on the left as 

 we look at the figure, yet the downthrown block forms a prominent 

 scarp rising above the ui)thrown block and worn only a little back 

 from the fault-plane. This is therefore a reversed erosion fault- 

 scarp caused by the greater resistance of the Lower Coal Measures 

 as compared witii the softer White Pine shales. 



FiGUJtii 4. — Faulting at Pioche, Nevada (after Howell). 



From U. S. Geographical Surveys West of the One Hundredth Me- 

 ridian, volume iii, Geology, page 259, figure 103. Shows ascend- 

 ency of erosion over faulting. Reversed erosion fault-scarp. 



A ^= Cambrian quartzite; C = Cambrian limestone of a higher hori- 

 zon than the quartzite. The fault shown in the section is a nornial 

 fault. The block on the right of the figure being relatively down- 

 thrust, the scarp showMi is a reversed erosion fault-scarp. 



Figure 5. — Faulting at Pioche, Nevada (after Howell). 



From the same page as figure 4. Shows ascendency of erosion over 

 faulting, a, erosion fault-valley ; h, fault with only slight effect 

 on toiwgrai)hy. In addition to the strata in figure 4, b here equals 

 Cambrian sliales intermediate in position between the limestone 

 and the quartzite. The fault at a has determined a fault-gully, 

 while the fault h has had very little influence on the topography. 



