1913] 



Louderback : 



The Monterey Series 



231 



exist as such. It would be impossible in any locality to draw 

 the actual line in the field between the beds corresponding to 

 one zone and those corresponding to the other, unless there 

 were a wholly terrigenous series well supplied with zonally 

 characteristic fossils. If a diatomaceous shale came in between 

 two sandstones, one with forms of the lower zone and the other 

 the forms of the upper zone, it would be impossible to tell to 

 which zone the shale belonged. 



It is a fact that the fossils given by Hamlin for his Vaqueros 

 formation belong to the Vaqueros fauna of Smith. But in the 

 "type" locality the distinction between "Vaqueros sandstone" 

 and "Monterey shale" was admittedly on a lithologic basis, and 

 who can say that the "Monterey shale" in part of that area 

 does not represent the "Vaqueros fauna" life period, or that 

 the "Vaqueros sandstone" of other parts of the area does not 

 represent the "Monterey-Temblor fauna" life period? 



As long as the Monterey series cannot be separated into two 

 (or more) formations of any general validity, but only locally 

 into lithologic types that vary rapidly in their thickness and 

 the horizon of their gradation zones, it seems artificial, unnec- 

 essary and confusing to label the faunal subdivisions or stages 

 with formational names. The only logical course is to give the 

 faunas faunal names, as has been done by Merriam. 



As soon as the sense in which Smith uses the terms Vaqueros 

 and Monterey-Temblor is clear it is easy to see that in but few 

 places where those terms have been applied will the division lines 

 or correlations of other geologists agree with his subdivisions. 

 Furthermore, in most of those fields no one could actually draw 

 the lines representing his divisions. 



The most noteworthy discrepancies are in the San Joaquin 

 Valley region, where Arnold. F. M. Anderson and their asso- 

 ciates have correlated the terrigenous sediments of the Monterey 

 series (Temblor of Anderson) with the Vaqueros. As pointed 

 out already, the indications are that they are in large part con- 

 temporaneous with certain "Monterey shale" of these authors — 

 and as no higher fauna is found there than that of the T. oeoyaiia 

 zone, and as the type "Vaqueros" was originally reported to 

 contain fossils of the T. hoffmanni zone, Smith's reference of 



