466 University of California Publications in Geology [Vol. 12 



Pidgas West Base. — Pulgas West Base was located in 1853 and 

 again in 1906p, but not in the interval between. In figure 16 let A be 

 the earlier position and B the later. In the interval 1853-68 the station 

 moved .87 meters in the direction 163° by strain creep to C ; thence 

 by rebound in 1868 1.54 meters to D; thence by renewed strain creep 

 2.2 meters to E in 1906a ; thence, by rebound, southeasterly parallel to 

 the San Andreas fault an unknown distance, on the line hb', com- 

 pounded with an apparent transverse shift which brought it to B. 



Fig. 15 Fig. 16 Fig. 17 



Fig. 15. The path of Black Mountain as determined by strain creep and 

 the rebounds of 1868 and 1906. 



Fig. 16. The path of Pulgas West Base as determined by strain creep and 

 the rebounds of 1868 and 1906. 



Fig. 17. The path of Sierra Morena as determined by strain creep and the 

 rebound of 1906. 



The component of the transverse shift normal to the fault is in this 

 case 1.33 meters, an exceptionally large figure, suggestive of a slight 

 error in the azimuth AB. 



Sierra Morena. — Sierra Morena on the west side of the fault was 

 located in 1883 and again in 1906a. It is situated 4.3 km. from the 

 fault. In figure 17 let A be the earlier position and B the later. In 

 the interval of twenty-three years between 1883 and 1906a the station 

 would have moved .058 X 23 = 1.33 meters in the direction 163° to C. 

 At the time of the earthquake in 1906 it moved by rebound northerly 

 parallel to the fault on the line bb' . But after the earthquake it was 

 found at B. The line bb' was apparently shifted parallel to itself to 

 B, and the component of this transverse shift normal to the fault is 

 .69 meters. 



Mt. Toro. — Mt. Toro, situated on the west side of the San Andreas 

 Rift but south of the region of slip in 1906, probably did not move at 

 the time of the earthquake of that year. At least there is no evidence, 

 or even suggestion, that it did. The station was located in 1885 and 



