LOCAL EFFECTS OF SAN FRANCTSCO EARTHQUAKE 307 



piled up into ridges 2 or 3 feet high, and at other places fissures 

 have been opened that measure 2\ feet in width. Two and a half 

 miles southeast of Portola the fissure is 3 feet across. The ground 

 is usually cracked and broken for a distance of 10 or 15 feet on both 

 sides of the main fracture, which in places splits up into numerous 

 minor cracks. 



Two miles southeast of Crystal Springs Lake the resistance to 



Fig. 4. — Showing a fence that crossed the fault at an obUque angle. The post 

 shown in the photograph was split and pulled apart and the wires broken. 



displacement appears to have been greater, and, instead of slipping 

 along a straight line, the ground has been broken into a belt of paral- 

 lel, north-and-south, shearing cracks, running at an angle of approxi- 

 mately 45° with the general movement. Some of these shearing 

 cracks are from i| to 2 feet wide, and the belt of cracks extends 

 for a quarter of a mile or more. 



Black Mountain was badly shattered, and there are numerous 



