PHYSICAL GEOGRAPHY 83 



members. The eastern half, from Point Moruga 

 eastward, comprises the Santa Monica Range proper. 



The rock materials are the familiar Cretaceous and 

 Tertiary sediments, with the granitics and metamor- 

 phics of the basement complex sometimes exposed be- 

 neath them, especially along the south fault scarp 

 line near Los Angeles. Toward the west end of the 

 Santa Monicas there are unusually fine displays of the 

 lavas, tuffs and dike material of the great mid- 

 Miocene volcanism, when the plutonic forces last 

 seemed active in this part of Southern California. 

 Beautiful exposures of these rocks may be seen in 

 Los Angeles in the cuts of Mulholland Drive as it 

 leaves the Cahuenga Pass Boulevard. 



It is impossible in this short paper fully to describe 

 the beautiful configuration and interesting structure 

 of these ranges. In general it may be said that they 

 are both bounded on the south by steeper escarpy- 

 ments than on the north, and that this escarpment 

 constitutes one of the great master fault lines of 

 Southern California (See details in chapter on **Struc- 

 ture"). To its escarpment we owe all the beautiful 

 "foothill" scenery of the Santa Monica and Holly- 

 w^ood districts. It is not easy to correlate the con- 

 figuration of these ranges to their structure, but the 

 fault line above mentioned is the master key to all the 

 other features of the range which, in fact, is but a 

 long and narrow, tilted, ribbon-like block on the north- 

 ern or uplift side of the fault. Many other structural 

 trends, principally of northwest-southeast extending 

 folds, may be found in this narrow, ribbon-like range as 

 in Griffith Park, but some were there before the moun- 

 tain was made by the uplift, as above described. 



