218 University of California Publications in Geology UVou 7 



"The fauna is characterized by a great abundance of indi- 

 viduals of several species of the genus Agasoma ..." 



Turning now to the "Monterey shale," "middle Miocene," 

 it is said that "In the Santa Cruz quadrangle the Monterey shale 

 consists chiefly of diatomaceous shale with here and there inter- 

 calated sandstone beds. . . . The diatomaceous shale composes the 

 greater part of the formation." 



"Locally the Monterey shale contains abundant fossils, leav- 

 ing no doubt as to its age. . . . Some of the areas of diatomaceous 

 shale supposed to be of Monterey age have thus far yielded no 

 determinable fossils" (p. 3). 



"Few species are known in the formation, but this paucity 

 in the number of species is partly compensated for by the abun- 

 dance or rather widespread distribution of Pecten peckhami 

 Gabb, Yolelia impressa Conrad, Area obispoana Conrad, and 

 Tellina congesta Conrad. The first two of these are found spar- 

 ingly also in the San Lorenzo formation (Oligocene) ; neverthe- 

 less their great abundance in the Monterey make them more or 

 less useful for purposes of correlation." 



We have the admission here that two of these forms are 

 found in the "Oligocene," and therefore cannot be considered 

 characteristic of the "age" of the shale, and it may be added 

 that Tellina congesta is one of the shale fauna that is found very 

 low in the Monterey series in Contra Costa County and it is 

 doubtfully determined by Anderson 64 in the shales near Coalinga 

 considered by Arnold and others to be Eocene or Oligo- 

 cene; and that Area obispoana er ' is reported from the Vaqueros 

 (Temblor of Anderson) associated with an Agasoma fauna in 

 the vicinity of Coalinga. One may hardly look upon these as 

 "leaving no doubt" as to the "middle Miocene" age of the 

 formation. A fossil list of 15 is also given with those "sup- 

 posedly characteristic of formation" indicated. For eleven of 

 these specific determinations are given of which all but two have 

 been reported from other localities as associated with "charac- 

 teristic ' ' Vaqueros or San Lorenzo fossils. The two not so found 



64 Anderson, Proc. Cal. Acad. ScL, 4th Ser., vol. Ill, p. 16 (1908). 

 Arnold, U. S. Geol. Surv. Bull. 396. p. 17 (1909), and Bull. 398, p. 86 

 (1910). 



