2 66 



PHYSICAL GEOLOGY 



height and prominence of which will depend upon the amount of 

 the faulting and its recency (Figs. 261, 262, 263). Fault scarps are 

 also formed when weak and resistant rocks are brought into contact 



Fig. 263. — The effect of faulting on the outcrops of anticlinal and synclinal 

 beds before and after the erosion of the fault scarp. 



by faulting. The weak beds are worn away more rapidly than the 

 hard, so that after prolonged erosion the latter may form cliffs, even 

 though they are on the downthrow side (Fig. 264). The original 

 fault scarp is usually soon eroded to such an extent that the con- 



a_ b figuration of the land gives 



/' little or no indication of the 



E ^^=z==^?=f==r^z existence of a fault. When, 



. BEMiSSHfe " however, a resistant bed such 



~ 7^*-. as a sill of lava (p. 326) or 



/ / ^^ ~~~ " H a quartzite stratum is present 



a and is exposed by erosion, the 



1 ^ — l fault will again be the indirect 



FlG. 264. — Diagram showing a cliff BAC cause of a chff (Fig. 264). In 



formed by faulting. As erosion wore away the Scotland the relatively soft 



weaker rock a cliff resulted from the presence rock§ of ^ central low l ands 



of rhe strong bed (,/). Upon further erosion 1111 



tin bed GF disappeared and the cliff F was have been brought up against 



formed. the relativelv hard rocks of 



