CRANDALL— SAN FRANCISCO PENINSULA. 



33 



on the northeast side. It is not quite straight but enters the area 

 on the west between the Ocean House and the Life Saving Station, 

 follows a southeast course swinging slightly toward the north as it 



Fig. II. 



Jasper remnant resting against sandstone at the point where the Lone Moun- 

 tain fault cuts the cliffs near the Presidio. 



reaches the bay one half mile north of San Bruno Point. The cres- 

 cent shape of the San Bruno hills is apparently directly related to 

 the form of this San Bruno fault line. 



In connection with the upthrust of the San Bruno block, an 

 anticline has been produced parallel to the axis of the fault. At the 

 point wdiere the railroad turns directly west, leaving the city near 

 Ocean View, a topographic saddle has been formed by the breaking 

 down of this anticline. In places this San Bruno fault distinctly 

 affects the topography : a line of low hills along the southwest side 

 of the ridge have jasper remnants exposed on their summits, show- 

 ing that they are geologically above the top of the San Bruno 

 mountain. The anticline developed by this fault may be seen quite 



PROC. AMER. PHIL. SOC, XLVI. 1S5C, PRINTED JULY 12, I907. 



