1914] Kew: Tertiary Echinoids of the Carrizo Creek Region 43 



numerous, and all the types are those which commonly live in more 

 or less muddy water. Both divisions are well exposed at the type 

 locality, but only remnants remain to indicate their former extent. 

 That the Lower Division at one time covered the greater portion of 

 Coyote Ridge is evident from the presence of mollusc borings in the 

 basal complex and small isolated patches of hard sandstone now 

 remaining on the crest of the ridge. "Whether the Upper Division had 

 the same geographic extent as the lower is conjectural, but the attitude 

 of the strata at the base of the ridge indicates that it probably extended 

 over the same area. 



The Lower Division of the Carrizo formation at Carrizo Creek and 

 Coyote Mountain rests upon the eroded surface of the basal complex 

 and also upon the andesite flow. The thickness of the strata is about 

 two hundred feet. At the base of this division, a coarse, angular 

 conglomerate prevails. This conglomerate often has a reddish color 

 and resembles somewhat a fanglomerate, but the presence of fossils 

 clearly shows it to be a subaqueous deposit. Above this is a wave- 

 washed arkosic sandstone, which is at places locally conglomeratic. 

 Farther away from the mountain, or from the old shore-line, the 

 sandstone becomes finer and at places tuffaceous. The large fauna 

 found in the basal series may be separated into two faunal assemblages 

 representing different facies of deposition, one indicating beach con- 

 ditions, and the other deeper water down to about fifty fathoms. A 

 marked distinction is found between these facies, especially in the 

 representation of echinoderms in the former, and the greater abund- 

 ance of gasteropods in the latter. Clypeaster bowersi and Encope 

 tenuis are very numerous in the beach sands, together with Clypeaster 

 deserti and Hipponoe calif ornica. Associated with these are a few 

 species of large gasteropods such as Dolium and Conns, and also a few 

 pelecypods, of which the pectens are the most abundant. The deeper 

 water fauna possesses a larger number of species, but the individuals 

 are generally smaller. The echinoderms found in this assemblage are 

 Clypeaster carrizoensis, which occurs abundantly, while Clypeaster 

 boiversi and Clypeaster deserti are rare and Hipponoe calif ornica was 

 not found at all. The greatest variety is in the gasteropods. Some 

 of the common forms are Turritella, n. sp., Oliva, cf. porphyria, Conus, 

 cf. betulinus, and Cancellaria, sp. 



The Upper Division shows a marked contrast to the lower beds. 

 These strata have a much greater thickness, which is estimated at about 

 two thousand feet in the Carrizo Valley. Near the upper end of the 



