PHYSICAL AND CLIMATIC SETTING 13 



and New York at the other. Between these two lo- 

 calities on the Atlantic there is a vast difference in 

 climate; within the two points named in California 

 there is so close a similarity that both meet the 

 temperature requirements of the orange. The differ- 

 ence on the two coasts is due to the following factors : 

 First, owing to ocean influences predominating over 

 land influences, the west coasts of continents in the 

 northern hemisphere are warmer in winter than the 

 east coasts. Second, northern California is addi- 

 tionally protected from low winter temperatures by 

 the mountain barrier of the Sierra Nevada, extend- 

 ing southward from the multiplied masses of pro- 

 tecting elevations in the Shasta region, while south- 

 ern California enjoys the protection of the Sierra 

 Madre and other uplifts on the north and east of her 

 orange region. Northern blizzards are, therefore, 

 held back from entrance to California and are forced 

 to confine themselves to their natural southerly and 

 easterly direction over the interior parts of the 

 Pacific slope, while the great blizzards of the north- 

 west traverse the Mississippi Valley and, if they have 

 sufficient impetus, extend to the Gulf and carry de- 

 struction to semi-tropical growths even in northern 

 Florida. The ocean bringing warmth and the high 

 mountains defending against cold combine to give 

 nearly the whole length of California semi-tropical 

 winter temperatures. Latitude becomes, therefore, 

 a small factor in the California climates. Third, the 

 several ridges of the Coast Range, with their in- 

 closed small valleys, serve as a colossal windbreak 



