Mountains of the South 247 



from vents in the surrounding land; and silt or very fine mud 

 swept into the sea by streams. The deposit thus made upon the 

 sea bottom became the silicious or diatomaceous shale of the 

 Modelo formation. 



During a later epoch, after the Modelo shale had been de- 

 posited, the great anticlinal fold or arch again was raised, and 

 the whole series of formations comprising the Santa Monica 

 Range was arched upward. The whole region henceforth re- 

 mained land, and erosion went on until from the crest and flanks 

 of the great arch much of the Modelo formation was removed. 

 The region continued to be worn down by streams and weather- 

 ing until the land became reduced to the stage of a peneplain 

 that is, worn down nearly to base-level or landscape old age. 



Finally in late Quaternary time (Pleistocene), the last geo- 

 logic epoch preceding the present or Recent, the arch was 

 uplifted to essentially its present height. Since the final up- 

 heaval of the range streams have cut deep canyons and the 

 present topography has been developed. 



Coastal Plain Affected by Changes 

 in Adjacent Land 



The Coastal Plain is not a part of the mountain range, but 

 the movements which have given form to the mountain range 

 have affected the coastal plain. Streams leading to the ocean 

 from the mountains have been affected by the uplifting of the 

 land. Changes in the elevation of the mountains have given 

 rise to the formation of terraces in the valleys of streams. 

 Hence the mountains may be said to be the controlling influ- 

 ence that determined the plain. 



Santa Barbara Islands Projecting Peaks 

 of Santa Monica Range. 



It should be stated further that the Santa Monica Mountain 

 range does not end where it is cut off by the sea at the west. 

 The Santa Barbara Islands are really mountain peaks which rise 



