1916] Marti)}: Pliocene of Middle and Northern California 241 



Six miles east of Capetown, at the mouth of the south fork of 

 Bear River, a small area of Miocene beds outcrops. These beds 

 extend across the river to the north side where a small area is 

 exposed. They consist of brown and gray sandstone. A few 

 poorly preserved fossils were obtained, among them a species of 

 Pecten, Glycymeris eonradi Dall, and Venericardia castor Dall. It 

 is probable that this small area was at one time connected with 

 the beds at the mouth of Bear River. 



Purisima Formation 



Physical Features. — The rocks of the Purisima Formation occupy 

 two geographically separate areas within the Santa Cruz Quad- 

 rangle, one on either side of the Santa Cruz Mountains. The one 

 of greater importance occupies an area triangular in shape stretch- 

 ing from Half moon Bay southward along the coast to the mouth 

 of Pescadero Creek, and then inward along Pescadero Creek to 

 its source. The northeastern boundary of the area extends from 

 the town of Halfmoon Bay southeast, more or less parallel to the 

 main divide, to the mouth of Oil Creek. From this point the 

 southern boundary follows Pescadero Creek northwest to Jones 

 Gulch, Avhere it turns due west for several miles, then turning 

 southwest toward the town of Pescadero. The narrow strip 

 extending south to Aho Nuevo Bay is limited on the east by a 

 prominent fault scarp along which movement took place, letting 

 the Purisima down against the Monterey shale. On the west it 

 is limited by outcrops of the Chico Formation on which the 

 Purisima lies unconformably. 



The area of Purisima thus outlined has been folded into a 

 syncline whose axis lie approximately in the middle, extending 

 southeast and northwest, conforming to the general structure of 

 the region. The northeast wing of the syncline flanks the west 

 slope of the Santa Cruz Range from Halfmoon Bay to Oil Creek, 

 overlying probably unconformably Monterey shale, Vaqueros sand- 

 stone, and Tertiary diabase. The general strike is N 40° W, and 

 the strata dip toward the southwest at an angle of twenty degrees. 

 The southwest wing of the syncline has been distorted by fault- 

 ing and has been partly submerged by the transgression of the 

 sea. The beds dip to the north and northwest at low angles, 

 usually not more than ten or twenty degrees. In some localities 



