FRANCISCAN AND POST-FRANCISCAN HISTORY 421 



have been crushed into small fragments and recemented by silica, forming 

 a lithologic variety which is in some degree characteristic of the forma- 

 tion. At Slate Springs the formation has been tilted into a nearly vertical 

 attitude by northeast-southwest stress, and a distinct series of fractures 

 and faults has been produced by a stress making a large angle with that 

 which produced the general dip. 



The complexit}^ of the cross folding and faulting in the Franciscan 

 series has prevented geologists from unraveling the detailed structure. 

 The problem is apparently not more difficult than that presented in the 

 Marquette iron region of lake Superior, and will yield to patient investi- 

 gation. We shall then know whether there is one or several strata of 

 radiolarian chert and limestone, and be able more adequately to under- 

 stand the oscillations of sealevel which resulted in the variations of 

 stratigraphy. 



Post-Franciscan History 



cretaceous land 



Elsewhere succeeding the Franciscan in normal section occur several 

 well known formations, namely, the Knoxville and Chico of the Creta- 

 ceous period, the Tejon (Eocene), and the Monterey (Miocene). Among 

 these formations are several unconformities of greater or less significance 

 and more or less widely extended occurrence. But in the region under 

 discussion, the northern Santa Lucia range, several of the formations be- 



PACIFIC SANTA LUCIA RANGE SAN ANTONIO VALLE.V SANTA LUCIA PEAK 



VNCISCAN < 



MIOCENE. COAST COM PL El 



Figure 1.— Generalized Section of Santa Lucia Range and San Antonio Valley. 



Taken from Gamboa point to Santa Lucia peak. The existence of the normal faults is inferred, 



not actually observed. 



tween the Franciscan and the Monterey are missing, and in the geologic 

 record there is a corresponding hiatus which is significant of profound 

 erosion. At Gamboa point, a few miles south of Slate Springs, the Fran- 

 ciscan formation occurs next to the ocean, extending from the shore up 

 to an elevation of approximately 3,000 feet upon the spurs of the Santa 

 Lucia range. The upper portion of the range east of this belt of Fran- 

 ciscan rocks is composed of the ancient Coast complex. Gneiss and 

 marble constitute the summit at Twin peak and Cone peak, 4,700 and 



