SURFACE APPEARANCE OF FAULTS 



813 



Features shown in surface appearance of faults, i. e., map features 



of faults. 



These features are seen in strike and oblique faults. In the 

 former the apparent horizontal displacement or offset is measured 

 along the fault line, and is the same as the actual horizontal dis- 

 tance between the ends of the corresponding strata (a b). (Fig. 

 195 A.) This is the same as the trend-slip, but is probably never or 

 but seldom the actual or net slip. In oblique faults the offset is 



A. Map of StriKe Fault 



'-'Ian or Map of 

 obllQ/ue Faalt 



I offset 



B. Plan or Map of 



oMicwae Fau.lt \ 



Fig. 195. Map or surface views of faults. 



measured at right angles between the two ends of the disrupted 

 strata, as (a b) in Figs. 195 B and C, where the trend-slip is 

 marked by a c. In Fig. B, the strata are disrupted and pulled apart ; 

 the distance thus separated is the gap. In Fig. C the ends are 

 pushed past each other, making an overlap, c b. ■ 



Classification of faults. 



Faults have been classified with reference to direction, as strike 

 (and bedding), dip and oblique faults. With reference to their 

 movements, they may be classified into normal and reverse faults, 



