SCIENTIFIC BACKGROUND 183 



in the continental trend which has taken place in this 

 general region. 



From studies of the structure plan it seems to me 

 that in past times, when the great warp or buckle 

 was created that set the Transverse folds and faults 

 crosswise to the normal northerly trends, there 

 were bends, buckles, slidings and overthrusts in that 

 too little understood portion of the Transverse Belt 

 where the various trends seem to meet. 



A buckle is a lateral bend. Stand a quire of paper 

 or deck of cards on its longer edge and push from one 

 or both ends, and the leaves (strata) will first bend and 

 perhaps later break and overcrowd along certain lines. 

 This is what has happened along the Transverse Belt of 

 California, the stresses acting in east-west directions. 

 The Ventura Ranges were flexured and horizontal 

 faults occurring along the San Andreas, Santa Ynez 

 and perhaps other lines. 



FOLDED STRUCTURES 



On previous pages I have shown that the processes 

 of folding and faulting are associated and parallel 

 phenomena in Southern California, although the latter 

 is more in evidence than the former. The rise of a 

 ribbon-like fault block composed of crystalline rocks 

 below and stratified rocks above may bend the latter 

 into folds. Likewise, the lower-lying, crystalline rocks 

 of such a structure, when denuded of the sedimentary 

 rocks, will appear as a faulted block; hence it is most 

 frequently the rule that where sedimentary rocks pre- 

 vail at the surface, folded structures are most in evi- 

 dence, and that where the metamorphic and granite 

 materials occur at the surface, the fault block struc- 

 ture is most apparent. Folding of the sedimentary 



