240 J. E. SPURR — ORIGIN AND STRUCTURE OF THE BASIN RANGES 



Kingston range. — The Kingston range, as viewed from the east and 

 north, appears to consist chiefl^y of a simple anticlinal fold in Paleozoic 

 limestones. Stuart valley, which lies east of its northern end, seems 

 synclinal. No faults were observed. Since the range lies next east from 

 the recently folded Funeral mountains, the structure suggests that it also 

 has originated by direct deformation. 



Mojave desert. — Southward from the Kingston and Funeral ranges 

 stretches the Mojave desert, where upturned beds, like those of the 

 Funeral range, occur. In the Calico mountains, near Daggett,* these 

 folded Tertiaries have been eroded to anticlinal valleys and synclinal 

 ridges, and there is a heavy fault which is not expressed in the topog- 

 raphy. These hills are therefore due to differential erosion. Either, 

 therefore, the uplift which affected them was earlier than that which 

 folded the Funeral Mountain region, or, granting that the disturbance 

 was simultaneous in both regions, it follows that for some reason erosion 

 has outstripped deformation in one locality and has been distanced by 

 it in the other. If the uplifts were indeed contemporaneous, erosion 

 must have been more active in the Calico mountains than in the Funeral 

 range, or deformation must have been more sluggish. Considering the 

 first alternative, we find that both regions possess the same intensely 

 arid climate, so that differences in rapidity of erosion, involving differ- 

 ences in precipitation, can hardly be postulated. Thus we are thrown 

 back on the second assumption. As a matter of fact, the folds shown 

 by Mr Storms are petty compared with the grand flexures of the Funeral 

 range. 



COLORADO PL A TEA U 



Eastward from the Basin ranges lies the Colorado j)lateau, where the 

 strata down into the Cambrian are level,t with the exception of occa- 

 sional simple swells wliich seem to have been contemporaneous with 

 periods of folding in the Basin ranges or the Wasatch. i The chief def- 

 ormation has been accomplished by a series of north-and-south faults, 

 which have generally expressed themselves directly in the topography — 

 that is to say, they are marked by simple fault-scarps.§ These faults 



* W. H. Storms : Eleventh Rept. Cal. State Mining Bureau, 1892, p. 347. 



tG. K. Gilbert : U. S. Geol. Survey West of the Hundredth Meridian, vol. iii, Geology, p. 196. 



C. E. Duttou : Tertiary History of the Grand Canyon District, Monograpli ii, U. S. Geol. Survey, 

 with atlas. 



C. D. Walcott: Am. Jour. Sci,, 3d ser., vol. xxxi, p. 437. 



XC. E. Dutton : Second Ann. Rept. U. S. Geol. Survey, p. 65. 



g J. W. Powell : Exploration of the Colorado, p. 182 et seq. 



C. E. Dutton: .Second Ann. Rept. U. S. Geol. Survey, pp. 117, 118, 124, 12.5, 120, 133, etc. 



G. K. Gilbert : U. S. Geol. Survey West of tlie Hundredth Meridian, vol. iii, pp. 43-57 ; yet for an 

 exception to the rule see Gilbert's last section on p. 50, wliere the scarp is on the downlhruwn side 

 of the fault, constituting a typical reversed erosion fault-scarp (see p. 25a, this paper). 



