30 CRANDALL-SAN FRANCISCO PENINSULA. [January 4, 



two quarries near Point Lobos avenue until Golden Gate Park is 

 reached where it is seen in Strawberry Hill, and one of the smaller 

 hills there that has a wooden cross erected upon it. This jasper 

 forms the crest of the ridge of hills in Sunset district, being ex- 

 posed only from i\l to S streets. Continuing, this formation makes 

 up the portion of the San Miguel Hills known as Sunny side Ad- 

 dition, and extends around the east and north side of those hills 

 almost to Valencia street. On the east side of the railroad tracks it 

 appears in the southwestern part of Holly Park and in irregular 

 areas on the northeastern side of University Mound. On the hills 

 just north of Visitation Valley and west of Railroad avenue the 

 entire thickness of the bed is seen. Two small hills of this jasper 

 occur, one on either side of the entrance to Visitation Valley. Their 

 relations are explained in the discussion of the structure. 



Silver Terrace Sandstone. — Lying between the lower and the 

 upper jasper bed is the Silver Terrace sandstone which consists of 

 a bed of sandstone and some tufifs which, together, have a thickness 

 of about five hundred feet. The tracing of the Silver Terrace sand- 

 stone and the associated tufif is much more difficult than tracing the 

 jaspers. The full thickness is exposed dipping into the northeast 

 from a point about a half mile east of Lobos Creek to a point about 

 a half mile northeast of Lobos Creek where the upper jasper is ex- 

 posed in a quarry on the Presido. It is present as an erosion remnant 

 in Golden Gate Cemetery, but does not appear between that place 

 and Blue Mountain. It can be traced around the west and south- 

 west sides of Blue Mountain and Twin Peaks, and it crosses a gap 

 between the latter place and Sunnyside Addition, and continues 

 around the eastern side of Twin Peaks to Buena Vista Park. Ero- 

 sion remnants cap the hills southeast of Buena Vista Park, Castro 

 street hill and Dolores street hill. In the eastern part of the city it 

 passes through the gap between Bernal Heights and Holly Park 

 and forms the Silver Terrace hills. The sandstone forms a floor 

 upon which rest the Hunter's Point serpentines and the two small 

 hills southwest of Hunter's Point. On top of the serpentine forming 

 Hunter's Point hills, is a small area of conglomerate belonging 

 with this sandstone. 



Upper and Lozcer Jasper Bed. — The Silver Terrace sandstone 



