1913] 



LouderbacJc: The Monterey Series 



1 89 



Results. — From the above considerations it is evident that 

 the division of the series at the base of the lower Modelo sand- 

 stone is an artificial division which holds in only a small part 

 of the Santa Clara field, and that the line as drawn to the west 

 of Sespe Creek and south of Santa Clara river is the same as 

 that used by Arnold in the Santa Maria district, — that is. the 

 base of the siliceous shales. 



Lithological Types and Nomenclature in Various Fields 



It should be particularly noted that the distinction between 

 Vaqueros and Monterey or Modelo has been actually made in 

 the field by Hamlin." Fairbanks. Eldridge, and Arnold, in the 

 Salinas Valley, San Luis quadrangle. Santa Maria district, Sum- 

 merland district, and Santa Clara Valley districts, on a strictly 

 lithologic basis, — that is, on a change in the type of sedimen- 

 tation, and we may represent the correlation of depositional 

 types in these districts by the following table in order to show 

 how the application of the nomenclature and the position of 

 the divisional lines have varied. 19 



is U. S. G. S. Water Supply and Irrig. Paper no. 89, 1904. 



It is evident that the questions here considered have nothing to do 

 with the determinations of horizons as indicated by faunal zones within 

 the Vaqueros-Monterey Series. 



