292 ELEMENTARY GEOLOGY 
was (Fig. 172). This is especially true where there 
are numerous faults near together. Sometimes many 
faults running in parallel directions produce the effect 
of step faults (Fig. 174). 
Ny 
Fic. 174. 
Diagram of normal faults. Step faults on right. 
If the angle of hade is great, and approaching the 
horizontal, the strata are thrust over one another hori- 
zontally. This condition is known as the overthrust 
fault, and the plane of faulting is called the thrust 
Fie. 175. 
Diagram of reverse faults. 
plane (Fig. 173). This may cause the bodily transfer 
of great blocks of strata horizontally for a distance 
of thousands of feet; and an overturned fold may 
change to an overthrust fault. 
Two of the most common dislocations are those 
