72 University of California, Publications in Geology [Vol. 11 



ing to Osborn, the White River Oligocene is very different from the upper Oligo- 

 cene of the John Day region and further shows distinct Asiatic and European 

 affinities indicating that the Bering portal was closed during Lower Oligocene 

 time. The John Day Oligocene fauna, however, lacks European affinities, thus 

 indicating that the Bering portal was open at this time. That a portion of the 

 John Day is the land laid equivalent of the Upper Marine Oligocene, the Acila 

 gettysburgensis zone is a probability. 



Since the climatic conditions of the Tejon and Lower Oligocene were much 

 the same, several species common to the two might be expected. Weaver reports 

 Br achy sphing us clarlci, Leda uvasana, CrassateUites washingtoniana, Exilia dicker- 

 soni, and Ecmifusus washiitgtoniaivus, as Tejon forms which also occur in the 

 Molopophorus lincolnensis zone. This is a very small number and, moreover, 

 further collecting has not increased it. It appears probable that a great interval 

 of erosion occurred between the beds bearing the Upper Eocene and Lower 

 Oligocene faunas and that the Tejon species finished their life course during the 

 time now represented in the rocks by an unconformable contact yet to be dis- 

 covered. 



The most recent paper 576 to appear, which deals with the marine 

 Oligocene of the West Coast, is by Katherine E. H. Van Winkle — 

 entitled "Palaeontology of the Oligocene of the Chehalis Valley, 

 Washington. 7 ' Miss Van Winkle, after a brief historical review, gives 

 a description of the stratigraphy, together with a faunal list of over 

 one hundred and fifty invertebrate species obtained from the Oligo- 

 cene of this general region of southwestern Washington. She accepts 

 the two faunal zones of the Lower Oligocene as outlined by Professor 

 Weaver, i.e., the Molopophorus lincolnensis and Turritella porterensis 

 zones, and besides these, also recognizes a new zone below the Molo- 

 pophorus lincolnensis zone, which she calls the Barbatia merriami 

 zone. Following the general part of the paper are the descriptions of 

 eighteen new species, accompanied by figures. 



DESCRIPTIONS OF LOCAL SECTIONS OF SAN LORENZO 



SERIES 



Two general sections of the Oligocene, both considered by the writer 

 as belonging to the San Lorenzo series, are found in the region of 

 Mount Diablo; one to the west and south of the mountain, along the 

 sides of the San Ramon Valley and in the Contra Costa Hills farther 

 to the west, and the other to the north, in the vicinity of Kirker Creek. 

 The beds of these two sections are so different, both in lithology and 

 faunas, that it seems best to consider them separately. 



57&Van Winkle, Katherine E. H., Univ. Wash. Publ. in Geol., vol. 1, no. 2, 

 pp. 67-97, pis. 6, 7, 1918. 



