Anderson.] 



Point Reyes Peninsula. 



133 



They constitute a remnant of probably the oldest formation in the 

 Coast Ranges of this latitude. There can be little doubt that the 

 series represented here by the limestone, quartzite, etc., is an 

 equivalent not only of a similar group of associates found upon the 

 San Francisco peninsula, but it is also a disconnected area 

 of a terrane more extensive in parts of the Coast Ranges southward. 

 In the Gavilan and Santa Lucia, if not also in the Santa Cruz 

 Ranges, these limestones are conspicuous and have often been 

 reared by orogenic action into prominent white peaks. The 

 crystalline character, the clustered scales of graphite, their associa- 

 tion with quartzites and crystalline schists and with granite, form 

 thus far the strongest evidence of the identity of these metamorphic 

 limestones which form the most important member of the series. 

 Their age has been conjectural, yet the evidence, such as it is, points 

 to a Paleozoic age. Paleozoic sediments of this character are more 

 common on the Pacific Coast than those of any other era. Both 

 at the north and at the south Paleozoic fossils have been found 

 that throw the weight of presumption in favor of this determination. 



In the Klamath Mountains metamorphic crystalline limestone 

 of Devonian age is found extensively and is characterized by each, 

 of the above features, singularly enough. 



In Siskiyou County graphite-bearing limestone indistinguish- 

 able from that of Point Reyes is found associated with vitreous 

 thin-bedded quartzite, wollastonite schist, and granite. It is in that 

 region, however, undoubtedly a continuation of the limestone 

 occurring at Gazelle from which Devonian fossils have been 

 obtained. 1 



LATER SEDIMENTARY ROCKS. 



Franciscan Series. 2 — Near the southern boundary of the field, 

 just west of Olema, and on the eastern slope of Whittenberg Hill, 

 there is a small area of dark gray limestone that is thought to 

 be the "foraminiferal limestone" of the San Francisco peninsula. 

 It contains a large number of veins of white calcite varying in 

 thickness from one-twelfth to more than one inch. The microscope 



1 Am. Jour. Sci., Vol. 147, pp. 416-422. 



2 Golden Gate Series of Fairbanks. 



