THE STRUCTURE OF THE EARTH 



265 



bedding fault. It should not be understood from the foregoing that 

 the movement in faults is always merely up or down. Often the 

 movement has both a vertical and a horizontal component, and occa- 



Fig. 260. — Diagrams showing A, horizontal strata; B, the strata displaced by 

 a vertical fault; and C, the fault scarp obliterated by erosion. 



sionally the vertical movement is inconsiderable and the horizontal 

 important. This was true of the fault that caused the San Francisco 

 earthquake (p. 275), and it has been observed in mines, where the 



A B C 



Fig. 261. — Diagram illustrating a dip fault and the effect of erosion upon the outcrop. 



faulted surfaces can be studied, that evidences of horizontal move- 

 ment are more often met with than those of vertical. 



Influence of Faults on Topography. — If faulting did not take place 

 long ago, it is evident that a cliff or fault scarp will be present, the 



Fig. 262. — Diagrams showing the effect of an obliqme fault upon dipping beds, 

 and the outcropping of the stratum on the surface after the fault scarp had been 

 planed by erosion. 



