San Francisco Bay and Golden Gate 



151 



now flows over the broad alluvial bottom of the lower half of 

 the original valley, the upper half having been diverted or 

 pirated to another stream. 



Drainage Affected by Faulting 



How the courses of drainage streams have been affected by 

 faulting of the rock formations is strikingly shown by a long 



After A. C. Lawson, U. S. Geol. Survey 



FIG. 48. Outline map of western slope of the Berkeley Hills, showing 

 the deflection of the streams by the longitudinal rift valley of the Haywards 

 fault zone. 



rift valley, the Haywards fault, which extends for several miles 

 parallel to the crest line of the Berkeley Hills (the Berkeley 

 uplifted block). This is shown in figure 48. It should be 

 noted that this fault is not the one that marks the boundary 

 of the Berkeley uplifted block, but occurred after the uplifting 

 of the main block, and after the streams that flow down this 



