1914] Dickerson : Fauna of the Martinez Eocene of California 81 



EELATIONS TO THE MAETINEZ AT SELBY SMELTER 



The Martinez at Selby Smelter is traceable southward to the 

 southern edge of the Napa Quadrangle sheet near Christie Station on 

 the Santa Fe railroad, a distance of six miles. Extensive overthrust- 

 ing has occurred, so that in places the Chico has completely over- 

 ridden the Martinez and even a part of the Monterey. The Martinez 

 at Selby was probably once connected with the southernmost tongue 

 of Martinez of the type locality, as their extensions are separated by 

 a distance of only two miles. A conglomerate in the Martinez is 

 found one quarter of a mile north of Vaca Canon near the Chico. 

 A small conglomerate area also occurs about one-half to three-quarters 

 of a mile north of Vaca Canon. Both dip at high angles to the north. 

 Whether these conglomerates are basal it is impossible to determine 

 positively from poor exposures and lack of fossils, but that such is 

 the eiise is strongly suggested. The great area of Martinez southeast 

 of Canada del Hambre, the tongue of Chico coming in between the 

 two extensions of the Martinez and a probable basal conglomerate 

 indicate that we have a closely folded, overturned anticline in this 

 portion of the type section which is locally broken by both strike and 

 cross-faults. On account of these structural complications, very small 

 exposures, if any, of the true base of the Martinez occur at the type 

 section ; but the major exposures are those of the upper and middle 

 portions of the group. Although the localities at Selby and Benicia 

 are structurally connected with the type locality, it is best to consider 

 them separately. 



FAUNAL ZONES 



We are chiefly indebted to Merriam and Weaver for the recognition 

 of two distinct faunal zones at the type section, viz., the Trochocyathus 

 zitteli and the Solen stantoni zones. Many students in the field classes 

 in palaeontology have collected near Muir Station, and from all of 

 these sources the writer has determined the faunas listed below. What 

 the persistent efforts of collectors will accomplish is well illustrated 

 by these lists when one knows how poor the collecting really is in 

 this field. 



