REDWOODS, RAINFALL AND FOG 



WILLIAM S. COOPER 

 University of Minnesota, Minneapolis, Minnesota 



The distribution of tlie redwood of California (Sequoia semper- 

 virens Endl.) has been commonly related to the summer fogs so 

 characteristic of the coast of that state. It is certain that other 

 influences have a share, notably rainfall; but no investigations 

 using other than merely observational methods have been made 

 bearing ujjon the relative importance of these and other factors. 

 The following study, though somewhat crude in method, yielded 

 fairly exact results as to the rainfall factor, and seems to offer 

 useful evidence bearing upon the problem. The work was 

 done during the rainy seasons of 1913-1914 and 1914-1915, in 

 the Santa Cruz Mountains, Stanford University being used as 

 a base of operations. My thanks are due to each member of 

 the staff of the Department of Botany of Stanford University 

 for assistance in many ways. 



The Santa Cruz Mountains trend northwest and southeast, 

 approximately parallel to the coast. East of them lie the 

 southern extension of San Francisco Bay and the Santa Clara 

 Valley, and west of them is the Pacific Ocean. Southward 

 they are a complex mass 30 km. in maximum breadth, deeply 

 cut by abrupt valleys and caiions. Northward they gradually 

 narrow, and opposite Palo Alto and Redwood City they have 

 more of the character of a single ridge with projecting spurs, 

 the longer ones pointing westward. Still farther north they are 

 again complex, but lower, and they finally die out in the hills 

 south of San Francisco. The east face of the mountain mass, 

 bsing a fault scarp, is nearly everywhere abrupt, and the highest 

 points of the range, such as Black Mountain (847 m.). Castle 

 Rock Ridge (912 m.), and Loma Prieta INIountain (912 m. +) 

 are near the eastern margin. 



179 



THE PLANT WORLD, VOL. 20. NO. 6 



