Clark: The San Lorenzo Series of Middle California 69 



faunas occurring in each of the following zones are distinct and many of the 

 species do not range into the zones below or above. (Weaver, C. E., op. cit., p. 4.) 



From the above it will be seen that Weaver has very radically 

 revised his ideas of the Oligocene, as published in the first paper 

 referred to. 48 The zones, as outlined, correspond only in general 

 with those given by Arnold and Hannibal. The beds of the Turritella 

 porterensis and Acila gettysburgensis zones were originally included 

 by Weaver in his Blakely formation and referred to the Lower Mio- 

 cene. The Molopophorus lincolnensis and Turritella porterensis 

 zones 40 are equivalent to the San Lorenzo formation of Arnold and 

 Hannibal, and the Acila gettysburgensis zone or Blakely horizon 

 apparently includes both their Seattle and Twin River formations. 



In a still more recent paper by Weaver, 50 the Oligocene is dis- 

 cussed in essentially the same manner as in the last paper just referred 

 to. Lists of characteristic species are given of the different faunal 

 horizons; there is also a check list at the end of the paper of post- 

 Tejon species of western Washington, together with their range indi- 

 cated in a table on the side. The following extracts, taken from this 

 paper, give Professor Weaver's ideas as to the probable correlation 

 of these beds and the relationships to each other of the different zones, 

 as recognized by him : 



Sufficient evidence is not as yet at hand to warrant a direct correlation 

 of the faunas or faunal zones of western Washington with those of California. 

 . . . The Molopophorus lincolnensis and Turritella porterensis zones of Washington 

 may be the equivalent of the Agasoma gravidum zone of California. It is pos- 

 sible that the Acila gettysburgensis zone is in part higher than the Agasoma 

 gravidum zone in the south. . . . The faunas of the Oligocene in western Washing- 

 ton show a gradual gradation from one zone into another. si 



A detailed study of the Oligocene beds opposite Seattle, Washing- 

 ton, on Puget Sound, the type section of his Acila gettysburgensis 

 zone is given by Weaver in a short paper entitled "The Oligocene of 



48 Weaver, C. E., A preliminary report on the Tertiary palaeontology of west- 

 ern Washington, Wash. Geol. Surv., Bull. 15, pp. 1-80, 1912. 



*9 The type section of the Molopophorus lincolnensis zone is situated in Thurs- 

 ton County along the banks of the Chehalis River between five and ten miles west 

 of the city of Centralia and west of the mouth of Lincoln Creek. This corre- 

 sponds to the type locality of Weaver 's Lincoln formation, described in the first 

 paper by him referred to. The type section of the Turritella porterensis zone 

 is located in Chehalis County in the region where Porter Creek joins Chehalis 

 River. The type section of the Acila gettysburgensis zone is in the vicinity of 

 Bremerton Navy Yard on Bainbridge Island, opposite the city of Seattle. 



so Weaver, C. E., The post-Eocene formations of western Washington, Proc. 

 Calif. Acad. Sci., ser. 4, vol. 6, no. 2, pp. 19-40, 1916. 



■ r 'i Weaver, C. E., op. cit., pp. 33-34. 



