THE SAX FRANCISCO 



EAUTlKJl'AKE 



7i 





Seven Mile Beach 



*jo«»> C,\o* 



Mu»el Rock. 



pliocene 



OUATERNAFCf 



Fig. 2. Section of Seven-mile Beach and Beyond; from mouth of Lake Merced, show- 

 ing position and exposure of Merced series of rocks. This remnant of this series lies between 

 the San Bruno fault plane at the north and the San Andreas fault at the south. Its entire ab- 

 sence from the San Bruno Mountains to the north and Mount Montana to the south is part of 

 the basis for the theory that since its deposition there has been uplift along the two faults 

 which lifted the terrritory outside of these faults nearly or quite a mile and one half above sea- 

 level, and that erosion, not only planed down the folded rocks of this block, but entirely 

 removed the Merced rocks either side of this block. 



San Bruno 

 , fault 



xa»-'i I La ke. 

 ,' 1 Ml treed 



lAfuod'sOiv/eh 

 Fault 



SenAndredS, 

 fault 



Mus&el 

 ffock 



Fig. 3. Figure showing Position of Recent Marine Deposits above Seven-mile Beach 

 and the relative movement along the two fault planes. 



Since then two events are clearly shown in the records; these are 

 subsidence and differential uplifts. The subsidence carried most, if 

 not all, of the San Francisco peninsula below its present elevation, 

 flooding the valleys and leaving the hills of the city largely an archi- 

 pelago. Marine deposits were laid down on top of the clearly recog- 

 nizable sand dunes and wash deposits, containing in many places 

 the trees mentioned above. Following that came local uplift, raising 

 these marine deposits to elevations of over 700 feet above sea-level just 



^-ji.Piji"* * *^ *"• >. afX^ 1 -S\ .1 v> A ■'ate. 



^>: :*• ^HC '^v -'^44^"'^ 



Fig. 4. Mussel Rock from the South, showing marine Pleistocene (o) overlying sand dunes 



(c) and igneous rocks (b). 



