46 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



quadrangle covers an area about two miles square, in the north- 

 west corner of the sheet. A smaller area of about three square 

 miles extends from Coal Canyon to Tuna Canyon near the 

 coast. Only small areas occur west of Santa Ana. The species 

 are such as flourish at a moderate depth, and show littoral con- 

 ditions. 



Review of the Martinez at the Type Locality 



It is desirable to review the Martinez of California and give 

 a summary of the literature. W. M. Gabb*', in 1869, recognized 

 a new horizon in his Chico Group near Martinez and on the 

 northern flank of Mt. Diablo. He did not, however, keep the 

 faunal horizons separate, and in 1895, Dr. T. W. Stanton' re- 

 vised the Chico and Tejon members and left the Martinez hori- 

 zon still to be determined. In 1897 Dr. Merriam^ published 

 lists of faunas with their stratigraphic positions, from a series 

 of rich localities running across the strike of the beds, from the 

 Chico to the Tejon. No unconformity was observed between 

 the Chico and Martinez beds and the faunas alone distinguished 

 them. Dentaliuni cooperii Gabb, was the only fossil found com- 

 mon to the two formations, and no overlapping of the faunas 

 was found to occur. Merriam's locality No. 1 is distinctly 

 Chico. Locality No. 2 is distinctly Martinez. Locality No. 3 

 furnished a fauna of the same type as No. 2, with the addition 

 of Tellina imdnlifera Gabb, Turri fella infra graiiulata (?) 

 Gabb ; Brachysphingus liratiis Gabb, and Modiolus ornatus 

 (Gabb), which is also characteristic of Tejon. From his local- 

 ity No. 4 he states that about one-third of the fauna is com- 

 posed of species known from the Tejon. However, when we 

 consider that over one-half of his species from No. 4 are new, 

 the Tejon species make up two-thirds of the species already 

 described, while only about one-ninth of them are characteristic 

 of the Martinez. 



In 1904, C. E. Weaver® described Dr. Merriam's Martinez 

 fauna and attempted to draw the line between the Martinez 



'Gabb, W. M., Rept. Geol. Surv. of California, Paleontology, vol. 2, p. 13, 

 preface, 1869. 



'Stanton, T. W., U. S. Geol. Surv. 17th Annual Kept., pt. 2, pp. 1011-1036, 

 189S-6. 



* Merriam, J. C, The Geological Relations of the Martinez Group of Cali- 

 fornia at the Typical Locality. Jour. Geol. vol. 5, pp. 767-76, 1897. 



* Weaver, C. E., Contribution to the Palaeontology of the Martinez Group, 

 Univ. Calif. Publ. Dept. Geol., vol. 4, pp. 102-123, 1904-6. 



