360 University of California Publications. [Geology 



But even under these conditions it would be difficult to account 

 for the practically total absence of decomposed material, espe- 

 cially in the finer members and towards the top of the series; 

 and one would naturally expect to find a greater proportion of 

 water-worn fragments than are actually present. Furthermore, 

 it seems difficult to account for the interbedded chemical sedi- 

 ments without at least some times of aridity, although these 

 may possibly have been merely accidents in a climate predomi- 

 nantly humid. 



The realization that of necessity essentially local conditions 

 of deposition must have prevailed has prevented the giving of 

 formation names to the different divisions of the series and the 

 consequent attempting of the correlation of beds of like charac- 

 teristics in the different localities examined. It is, however, 

 realized that the series as a whole is a fairly homogeneous unit 

 and that the same general origin and conditions of deposition 

 can be invoked to account for the characteristics of the strata 

 in all of the different localities. 



FIRST EPOCH OF DEFORMATION OF THE ROSAMOND 



SERIES 



The Rosamond Series has suffered the effects of two epochs 

 of deformation. The structure produced by the first diastroph- 

 ism has been described in the descriptions of the various local- 

 ities. It is noteworthy that the deformation produced not only 

 folding but also faulting both of the reversed and normal types. 

 The folding was both of the broad and open variety and of the 

 intensely compressed form, accompanied by overthrusting. The 

 massive, more competent beds appear to have deformed into the 

 broad, gentle folds, or to have been in places only tilted; and 

 the faulting in these beds is in many places certainly of the 

 normal type. As many of the fault planes are vertical or very 

 nearly vertical, some of the faulting may have been produced 

 by upthrusting. The finer bedded, less competent strata in the 

 Calico Mountains exhibit typical Appalachian structure with 

 close folding and overthrusting. It is quite probable that, at 

 the time of the earlier deformation, the Rosamond beds formed 

 the surface rocks of the region deformed, and that the defor- 

 mation occurred soon after the deposition of the beds. 



