t 



90 



GUIDEBOOK OF THE WESTERN UNITED STATES. 



earlier and. for the most 



movement 

 20 feet, r 



prehistoric movements. The last 



Andreas rift, avS this fissure has bee 

 ^rancisco, and its course is marked 



(p. 90). 



The cracks in the soil that mark the line of the la.st displacement 



NW.i 



XXXIII 



older displacements along the fault zone are well displayed in Spring 



Valley, 13 miles south of 

 San FranciscO; and es- 

 pecially near Skinner's 

 ranch, 40 miles north- 

 west of San Francisco. 

 To reach Spring Val- 

 ley the visitor should 

 take a Southern Pacific 



Trees 



House 



House 



/a) 



C^) 



\ 

 I 



1! 



U.I 



I 



I 



I 



I 



I 



!' Trees moved ISfeetSE. 

 . with reference to bouse 



iGURE 12.— Earthquake effects at Skinner's ranch, near Olema, 

 Cal, The i-elative position of the ranch house and trees on op- 

 posite sides of the fault plane shows that tlie horizontal move- ^^*^^^ 



ment was about 15 feet. «, Before earthquake; 5, after earth- Hules) 

 quake. 



Mateo 



foi- a drive through Si)ring Valley along Crj 



Andrens lakes. 



ance may be obtained 



and San 



Skinner's ranch can be reached by the ferry to Sausahto and the 



^v ^ ^ _■_ _ ■_ 



from 



the ranch is only 2 miles distant, near Olema. In this region may be 



acks „ 



ranch 



there, is striking evidence of the horizontal character of the movement 

 that produced the earthquake. The house formerly had two trees in 



front of it- 



which 



the trees and the house, and the trees were moved 15 feet to the 



southeast with reference to the house. (See fig. 12.) There was no 



perceptible vertical movement nor any change in the water hne along 

 Toniales Bay. 



