FAULTS ; 169 

the same district, which is usually the case, the latter are 
intercepted by and do not cross the former. And similarly, 
when the dip-faults are stronger than the strike-faults, they 
cut these off. 
Shifting of Faults.—This latter rule is so general, that 
when we find one fault crossing and shifting another, we may 
reasonably suspect that the two faults belong to different 
periods of disturbance. 
The relative age of inter- 
secting faults is at once 
revealed by the fact that 
the younger dislocation 
shifts the older, just in the 
same way as any fault dis- 
places strata. The pheno- Fic. 48.—SHIFTING OF ONE FAULT 
mena are illustrated by the BY ANOTHER. 
diagram (Fig. 48), where 
a @ is obviously the older fault since it is displaced by the 
other (4 3), 
Displacements of this kind are of common occurrence in 
much-disturbed regions, and prove that such areas have been 


FIG. 49.—INTERSECTING FAULTS. 
The feathered arrows indicate dip of strata; the small arrows show downthrow 
side of faults. 
rent and dislocated at separate—often widely separate— 
periods, In countries where ore-bearing veins are well 
