Geology from a Motor Car 383 



Long Straight Valley Marks San 

 Andreas Fault 



At Palo Alto (Spanish for tall tree) to the west of the high- 

 way is Stanford University. The buildings are of buff sand- 

 stone taken from a quarry 10 miles south of San Jose, of Mio- 

 cene (Monterey) age. The San Andreas fault, movement 

 along which caused the earthquake of 1906, which greatly 

 damaged the buildings of the University, is four miles west. 

 Between Redwood and San Carlos, five or six miles west of Palo 

 Alto, the even-crested forest-covered Cahill Ridge may be seen 

 west of the highway. Between this ridge and the foothills near 

 the highway is a long narrow nearly straight valley which marks 

 the San Andreas fault. Two lakes, San Andreas and Crystal 

 Springs lakes, have been formed by damming, and these supply 

 much of the water used by the city of San Francisco. 



A little beyond Belmont, to the right (east) , may be seen 

 the salt marshes and the white salt fields where salt is obtained 

 by solar evaporation of water from the bay. Along this por- 

 tion of the salt marsh which borders the bay fresh water is ob- 

 tained from wells of various depths up to 400 feet. This fresh 

 water evidently comes from formations that lie below the salt 

 water. At high tide when the flats are covered by salt water 

 some of the fresh-water wells flow over the surface from the 

 hydrostatic pressure of the heavier salt water. 



At San Mateo a creek of the same name is crossed, which 

 carries water from Crystal Springs Lake in the San Andreas rift 

 valley to San Francisco Bay. The lake is one of those formed 

 by dams in the creek. At San Mateo an alternate route may 

 be taken into the city by turning on Crystal Springs road to 

 Skyline Boulevard, which runs along the San Andreas rift, and 

 returns to the highway at Colma. 



East of Millbrae, in the bay, are oyster beds where young 



