200 W. M. CAVIS NOMENCLATURE OF SURFACE FORMS 



when even the orthodox geological evidence of faulting, based on displace- 

 ment of corresponding structures, also failed to command general accept- 

 ance among geologists. 



After faulting ceases the terminal facets of fault-scarp spurs will lose 

 their sharpness of form ; their edges will be rounded off, their faces will 

 be worn back from the fault line, and although they may still for a time 

 be arranged along a comparatively simple line indifferent to the struc- 

 ture, the unequal retreat of spurs of different resistance must eventually 

 bring about an increasing irregularity in their ending. If the lowland 

 forward from the irregularly retreating spurs is then still covered with 

 transported waste, as frequently happens, the evidence of the fault will 

 weaken, just as the usual geological evidence of a fault weakens when the 

 outcrops by which it is ordinarily proved are covered by transported waste. 

 But in either case, if the transported waste is removed and tbe rocks 

 or their local soils are revealed, the evidence of faulting becomes mani- 

 fest by the difference of soils on the two sides of a simple line, as in the 

 cases already stated above. 



Examples of maturely dissected Fault Scarps 



The western face of the Wasatch range in Utah and the eastern face 

 of the Sierra Nevada in California are regarded by various observers as 

 fault scarps of great dimensions, more or less elaborately dissected. The 

 latter example is largely composed of massive crystallines and, as far as 

 it has been described, does not seem to present subsequent details due to 

 erosion guided by exposed structures: the former example is largely 

 composed of disordered stratified formations and is marked throughout 

 by an abundance of subsequent details. Gilbert ( '90, 340-) has briefly 

 described the main scarp of the Wasatch, but has given more attention 

 to the signs of recently renewed faulting along the scarp base. Hunting- 

 ton and Goldthwait ('04,230) have studied the southern part of the 

 Wasatch scarp; and in my own papers are some details regarding its 

 middle part, which near Provo exhibit some well preserved terminal 

 spur facets (b. '03, 152), and near Xephi some striking subsequent fea- 

 tures oblique to the trend of the scarp ('05, 21") : also some account of 

 more maturely dissected scarps along the western sides of the Canyon 

 and House ranges ('05, 29-, 46-). Diller has presented short statement- 

 regarding the repeated scarps of the northern Sierra Xevada ('86, 12), 

 and Russell ('89, 279) regarding the great single scarp farther south, in 

 the neighborhood of Mono lake. More recently Eeid ('11, lit) has de- 

 scribed strong scarps in the Lake Tahoe district. Lawson ('12) adds 



