Geol— Vol. II.] ANDERSON— CRETACEOUS DEPOSITS. 1 3 



Barbara County northward toward Sonoma. It is involved 

 in a number of lesser ranges along the coast, among which 

 are the Santa Lucia, Santa Cruz, and Montara ranges, and 

 others on the coast north of San Francisco. The age of 

 these granites is a matter of uncertainty, and it is conjec- 

 tural to suppose that their movements have been contempo- 

 raneous with those of the Sierra Nevada; but this is 

 immaterial so far as the Cretaceous deposits are concerned, 

 which, as has been said, occupy a position for the most 

 part intermediate between the two, and only occasionally 

 touch the granites of either mass. 



The components of the basement series upon which they 

 rest are of various ages, and have roughly a concentric 

 arrangement with reference to the Great Valley, forming a 

 succession, inward, of Paleozoic and earlier Mesozoic 

 rocks. The latest of these whose age is definitely known 

 are the Mariposa slates of the Sierra foot-hills. In the 

 Coast Ranges the unconformity of the Knoxville strata upon 

 those of the Franciscan series, as at Mount Diablo, Santa 

 Margarita, and other places, makes it apparent that this 

 formation, which is probably also of Mesozoic age, forms 

 a part of the basement of the Shasta-Chico series. Beyond 

 the Mariposa slates on the east are the still older rocks of 

 the Calaveras formation, while in the Coast Ranges, between 

 the strata of the Franciscan series and the coastal granites, 

 is found a series of ancient crystalline marbles and quartz- 

 ites that can hardly be thought younger than the Paleozoic. 

 Concentrically with these, tnough often overlapping them, 

 are the later Mesozoic rocks of the Cretaceous, ranged 

 along the borders of the Great Valley. 



Northward, in the Klamath Mountains, the underlying 

 rocks range down in age even to the Devonian and older. 

 Near Yreka, in Siskiyou County, Cretaceous deposits are 

 found resting upon a series of micaceous and quartz-schists 

 of either Devonian or earlier age. Throughout the region 

 these schists are mantled over by a series of slates, gener- 

 ally either silicious or calcareous, that remind one strongly 



