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San Fernando Valley and Pass 



The San Fernando Valley is a deep basin of Tertiary and 

 Quaternary deposits, cut off at its eastern end by a fault which 

 marks the boundary of the Verdugo Mountains and San Rafael 

 Hills. The northwest end of the Verdugo Mountains is cov- 

 ered with Miocene (Tertiary) sandstones and conglomerates. 

 A short distance east of Pacoima an isolated hill, geologically a 

 part of the Verdugo Mountains, stands above the alluvium. 

 The south side of this hill consists of granite. To the east, 

 between Pacoima and San Fernando, the San Gabriel Mountains 

 may be seen, rising in the western part of the range to an alti- 

 tude of more than 5,000 feet above sea level. The main mass 

 and higher parts of the mountains are formed by a huge block 

 of granitic and metamorphic rocks which have been pushed up- 

 ward. It is bounded on all sides by faults. 



Northwest of San Fernando is San Fernando Pass, which 

 marks the junction of the crystalline mass of the San Gabriel 

 Mountains with the sedimentary rocks of the Santa Susana 

 Mountains. The Santa Susana Mountains are formed by an 

 uplifted block with a large thrust fault along its south side. 

 The San Fernando Mission, one of the old California missions, 

 is passed in going westward from San Fernando. From Devon- 

 shire Street, in the vicinity of the junction with Reseda Avenue, 

 a good view can be obtained of the south side of the Santa 

 Susana Mountains. The main mountain mass has been over- 

 thrust by faulting from the north toward the south. Along 

 the Santa Susana fault, which is the uppermost of three faults, 

 older (Miocene) beds are thrust over younger deposits (of Plio- 

 cene or Pleistocene age) . The south edge of a terrace of sand 

 and gravel hangs about 500 feet above the level of the valley 

 floor, the terrace tilted northward toward the Santa Susana 

 fault. The Santa Susana fault is well marked north of Chats- 

 worth, where Brown Canyon has cut a steep cirque-like face 

 in the mountain wall. 



