Vol. XI] DICKERSOX—PT. REYES AND SANTA ROSA QUADRANGLES 557 



the latest Pleistocene, but he did not consider the possibility 

 that more than one warm epoch might be represented in the 

 marine sequence of the Pacific Coast. A small fauna from 

 California Academy of Sciences Location 571, situated 200 

 feet northeast of California Academy of Sciences Location 

 562, on the northeast end of the headland opposite Inverness 

 Yacht Club, on the east side of Tomales Bay, three-quarters 

 of a mile northeast of Millerton Station, demonstrates that 

 a second warm epoch was probably present in the Tomales 

 Bay region. This fauna consisting of Chione undatella Car- 

 penter and Ostrca lurida Carpenter, is closely associated with 

 cones of Pinus radiata. The two localities just mentioned are 

 separated by an unconformity between the Tomales and Mill- 

 erton formations. 



Later work by Professor J. C. Merriam* and others upon 

 the vertebrate and invertebrate faunas obtained from the 

 Rodeo beds gives evidence that the vertebrates from this lo- 

 cality do not apparently represent the same stage of evolu- 

 tion as those from the Rancho la Brea beds. To quote from 

 this guidebook: 



On the borders of a swamp near the oil refinery of the Union Oil 

 Company are exposed vertical strata of Pinole tuff, composed of light 

 yellowish or white pumice. These strata dip at a relatively low angle on 

 the southwest side of the syncline. The axis of the asymmetric Pinole 

 syncline passes through the swamp. The Pinole tuff, having a thick- 

 ness of about 1000 feet, was laid down in part, at least, in a lake basin. 

 Freshwater shells belonging to the genus Physa have been found in 

 the strata on the eastern side of the swamp. Rodeo-Pleistocene beds 

 rest upon the Pinole tuff at this point. Further west the Pinole tuff is 

 exposed in the railroad cuts near Rodeo Station. Just west of this 

 station easterly dipping beds of the upper San Pablo are exposed. At 

 Hercules Station the shattered Monterey strata which form the lower 

 portion of the western limb of the Pinole syncline are seen. West of 

 Pinole Station the Pinole tuff is in contact with the Monterey. 



The Pleistocene deposits of San Pablo Bay have been referred to fre- 

 quently as the Rodeo beds. They are well exposed in the sea cliffs near 

 Rodeo and Pinole. Near Rodeo Station the horizontal Pleistocene 

 strata rest upon sharply tilted beds of San Pablo-Miocene and Pinole 

 Tuff-Pliocene. At a number of localities the basal layers of the Rodeo 

 are made up almost entirely of marine shells, comprising mainly 

 oysters and mussels. Above the shell layer the deposits grade into beds 

 of estuarine or alluvial origin. The thickness of the Pleistocene in this 

 region is commonly not over 40 feet. 



13 Merriam, J. C, and others, Preliminary Program and Outline for Excursions for 

 Meeting of the Paleontological Society, pp. 8-10, 1915. 



