EOCENE FORMATIONS. 11 



MARTISKA FOUMATIOX. 

 TYPE LOCALITY. 



The type locality is south oi the town of .Martinez, Contra Costa County, Cal. 



NAME ANT) DESCRIPTION. 



This formation was named and described by .1. D. Whitney in California 

 (li'ological Survey, Paleontology, vol. 2, 1869, preface, ]). xiii. 



DEFINITION. 



Dr. J. C. Merriam, in his paper on "The geologic relations of the Martinez 

 group of C!alifornia at the typical locality,"" gives the followiijg- definition of the 

 Martinez formation, which is generally accepted by paleontologists and geologists: 



"The Martinez group, comprising in the typical locality between 1,000 and 

 2.000 feet of sandstones, shales, and glauconitic sands, forms the lower part of a 

 presumably conformable series, the upper portion of which is formed by the Tejon. 

 It contains a known fauna of over sixty species, of which the greater portion is 

 peculiar to itself. A number of its species range up into the Tejon, and a very few 

 long-lived forms are known to occur a'lso in the Chico ((Cretaceous). Since the 

 Martinez and Chico are faunally only distantly related, it is probable that an uncon- 

 formity exists between them. Though satisfactory correlation of California forma- 

 tions with the sulxlivisions of the standard geological scale can be accomplished only 

 when the local scale is fully worked out, we may, for the present at least, accept 

 Mr. Stanton's correlation of the Martinez with a portion of the Eocene." 



LOCALITIES. 



Martinez, Clayton, rai-hecu, and Army Point (near Benicia), Contra Costa County. 



Lower Lake, Lake County. 



Between headwaters of Peseadero Creek and San Lorenzo River, San Mateo County (?). 



Rock Creek, Los Angeles County. 



Point Loma, San Diego County (Eocene here may include the Martinez). 



FAUNA. 



« 



Peeten fauna. — The Pecten fauna of this horizon consists, so far as known, 

 of only one species, JWfi-n {('Maiiujft) jrroaviiK n. sp., and this from a locality of 

 doubtful Martinez age. 



ti.»our. (ifol., vol. 5, p. 77d. 



