Faults Inferred from Topography 



79 



Figure 68. Fault map based chiefly on sea floor topography. Locally, positioning was aided by data on stratigraphy 

 of the sea floor and by extension of known faults on land. Wide lines indicate long primary faults; narrow lines show 

 shorter secondary fauhs, some of which may prove on future study to be the Umbs of folds. Note that many of the 

 secondary faults or folds have a more westerly trend than the primary faults. 



on the sea floor (Norris, 195 1 ; Menard et al, 

 1954). In the latter block several troughs 

 and ridges are indicative of synclines and 

 anticlines; however, they are shown on the 

 structural map as faults because of the im- 

 possibility of distinguishing between faults 

 and steep limbs of folds on the basis of 

 topography alone. 



The alternating hills and depressions along 

 the primary faults may be a result of sec- 

 ondary dip-slip faulting or of folding with 

 trends at an acute angle to the primary 

 faults. Either feature may possibly be the 



resuk of large drag movements along the 

 primary faults if the latter are strike-slip 

 faults. As pointed out by Reed and Holhs- 

 ter (1936, p. 127) and by Moody and Hill 

 (1956), many large strike-slip faults on land 

 are bordered by drag features of similar ap- 

 pearance. The axes of these secondary fea- 

 tures trend more westerly than the primary 

 faults, indicating a right lateral, or clockwise, 

 movement along the strike-slip primary 

 faults. In addition to these large primary 

 and secondary faults, there must be a net- 

 work of small ones similar to those revealed 



