MATERIALS OF THE EARTH 



67 



throw was to the left, and that shown in Fig. 45 if the downthrow 

 was to the right. In the former case, it is said that there is offset 

 with overlap; in the latter offset with gap. The amount of the 

 overlap and gap, respectively, increases with the increase of throw 



Fig. 46. Diagram showing effect of faulting on the outcrops of synclinal 



beds. 



and hade, and decreases with increase of dip. In all cases the 

 outcrop (after the degradation of the upthrow side) is shifted 

 down dip. 



If a fault crosses folds at right angles to their axes, the effect is 

 to change the distance between the outcrops of a given bed on 



Fig. 47. Diagram showing effect of faulting on outcrops of anticlinal beds. 



opposite sides of the fault, after the truncation of the folded beds. 

 The distance is decreased on the upthrow side of a syncline (Fig. 

 46) and increased on the upthrow side of an anticline (Fig. 47). 



Various other complications arise under other circumstances. 

 Since fault-scarps are not common, the detection and measurement 

 of faults is usually based on the study of the relations of the beds 

 involved, as illustrated by Figs. 41-47. 



