THEORIES OF THE CAUSES OF FAULTING 203 



RECURRENCES OF TRENDS 



There are also suggestions of the recurrences of 

 the same direction of trend in different epochs. The 

 northwesterly trends of the Coast Ranges and Cata- 

 lina groups, probably made at the close of the Miocene, 

 were apparently next replaced by east-west and tor- 

 sional directions in the late Pliocene and earliest Pleis- 

 tocene epochs, though still later they may have re- 

 peated themselves in the Pleistocene and Recent epochs. 



The fact that the various trends cross one another 

 at various places in Southern California has already 

 been set forth. At first glance the student might 

 conclude that this crossing of the master faults and 

 belts of faults is due to complemental faulting. If such 

 be the case in some instances, I do not know of them. 

 On the other hand the proofs of the existence of fault 

 belt groups of different ages and of the fact that they 

 have crossed one another are too positive to be ignored 

 and I believe the explanation for this crossing will 

 be found in the conditions just described. 



