290 B. L. CLARK THE MEGANOS GROUP 



were listed either by Stanton or Dickerson in the papers already referred 

 to. This upper fauna^ referred by Dickerson to his Balaniphyllia zone, 

 contains many of the species which are so typical of the type section of 

 the Tejon, such as Meretrix liornii Gabb, Meretrix tejonensis Dickerson, 

 Conus remondii Gabb, Ficopsis cf. cowUtzensis Weaver, Turritella 'uva- 

 sana Conrad, Turritella uvasana hicarnata Dickerson. 



The fauna of the Meganos, as obtained from the section described 

 above, is very different from that of the Tejon. Sixty-five species, listed 

 above, have been recognized in this fauna; of these, 4, possibly 6, are 

 found in the Tejon beds immediately above; 2 or 3 more are found in 

 the Tejon of other sections. It is interesting to note that over half of 

 the Meganos species are new; also that a number of these forms are 

 found in beds in the southern part of the State, which have been referred 

 to as being Martinez in age. Eeference will be made to this occurrence 

 further on in the paper. 



It is the writer's conclusion, after comparing this fauna from the 

 Meganos beds with that of the Tejon, that here is good evidence which 

 points to a marked faunal as well as stratigraphic break between these 

 two horizons. 



Meganos Group to South axd West of Mount Diablo 

 general statement 



A study of the Eocene section on the south and west sides of Mount 

 Diablo has shown that here also the Meganos beds are present and lie 

 unconformably below the Tejon. One of the best known sections of the 

 Eocene of the Momit Diablo region is found on the south and west sides 

 of the mountain, the maximum thickness in this area being about 2,500 

 feet. These beds are described in a recent publication by Dr. E. E. Dick- 

 erson.^ Here he establ'shed three faunal zones, all of which he referred 

 to the Tejon. The lowest zone he called the Turbinolia zone; the fauna 

 from near the middle ol the section he referred to his Eimella simplex 

 zone, while that found in the upper beds was referred to his Balanophyllia 

 variabilis zone. 



The writer's conclusions, after studying the fauna from the south and 

 west side of Mount Diablo, is that the beds containing the faunas desig- 

 nated by Dickerson as the Turbinolia and Eimella simplex zones are not 



8 R. E. Dickerson : Note on the fiunal zones of the Tejon Group. Univ. of California 

 Puhl. Bull. Dept. Geol., vol. 8, no. 2, 1914, pp. 17-25 ; Stratigraphy and fauna of the 

 Tejon Eocene of California. T'niv. ^f California Publ. Bull. Dept. Geol., vol. 9, no. 17. 

 1916, pp. 363-524. 



