LOCAL EFFECTS OF SAN FRANCISCO EARTHQUAKE 309 



in length, and the road from San Mateo to Half Moon Bay runs 

 along its crest. The accompanying sketch (Fig. 7) shows the position 

 and direction cf the cracks that were formed in the dam. The 

 larger cracks are about 6 inches wide and are parallel with the dam. 

 Smaller intersecting cracks were formed near the northeast end 

 of the dam along the probable line of the fault, and the road was 

 cffset about 6 feet at this point. The fences en both sides of the 



Fig. 6. — Photograph of a fence crossing the fault-Une at right angles. The man 

 is holding an eight-foot transit rod and stands in line with continuation of the fence on 

 the far side of the fracture. The fence was repaired before the photograph was taken. 



road were broken in a number of places, and the unbroken boards 

 were bent and arched so as to give a serpentine appearance to the 

 fences. The wires of a telephone Hne crossing the dam sag in great 

 loops. 



It seems probable that the total displacement is greater than the 

 amount that may be directly measured at any place along the hne 

 of the fracture, for there is evidence of drag in the soil fcr a consid- 



