214 QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



Ceritlmtm PilUngi, u. sp. 

 Vcrithium totiiim sanctorum, n. sp. 

 Solarium iraUalense, n. sp. 



The collection from Mendocino County included the first and the last of 

 these and also imperfect specimens of an Inocerannis about a foot in length, 

 X)strco, Peclen, and Turritella. Dr. White believes this fauna to indicate 

 the middle Cretaceous and in some respects it reminds him of the Gossan.' 



The Wallala beds have never been recognized except at these two 

 points, which are 600 miles apart. The northern locality was manifestly 

 close to the shore of the ocean of that time, and the locality in Lower 

 California appears to have been similar. It thus seems probable that the 

 western slioreof California was approximately in its present position during 

 the Turonian epoch. 



The chico-T jon series. — This group of rocks occurs for the most part on 

 the slopes of the great valley of California, the western side of the Coast 

 Eanges being covered with Wallala beds or Miocene strata where the meta- 

 morphic series is not exposed. The prevalent rock variety is sandstone of 

 medium grain and usually very soft.^ The lower portion of the series is 

 generally ferruginous and of a tawny hue, and spheroidal concretions, 

 though met in later sandstones, also are particularly abundant in the 

 Cliico. The origin of these concretions is discussed in Chapter III. The 

 upper part of the series is commonh' characterized by an extremely light 

 color, approaching pure white. The series also includes shales, though 

 these are subordinate, and a very little limestone is met with in some 

 localities, though not forming continuous strata. Along the Coast Eanges 

 the Chico-T(.jon series is, so far as I know, always perceptibly inclined and 

 usually at a considerable angle, but in some of the localities on the west 

 flank of the Sierra Nevada, as at Chico, the beds are very nearly horizontal. 

 Traces onl}^ of cinnabar are known to occur in these rocks and no case of 

 metamorphism similar to that which prevails in the rocks of the Knoxville 

 group has been observed, though induration and a greater or less impreg- 

 nation with calcite and gypsum are not uncommon. 



' Bull. U. S. Geol. Survey No. 22. 



- The branches of bushes growing close to croppings of these sandstones often wear grooves into 

 the rock which are sometimes as much as three inches in depth. 



