PHYSICAL GEOGRAPHY 81 



among the most peculiar and interesting. These are 

 a conspicuous assemblage of narrow, elongated, parallel 

 ranges varying from two to five miles in width, which 

 alternate with the valleys of somewhat similar dimen- 

 sions. Among the features included in this group, the 

 following may be mentioned : Sulphur, Hopper, Santa 

 Paula, Oak Ridge, Santa Susanna, Simi and the ranges 

 north of Camarilla and Calleguas Hills, 



These individual mountains occur end to end in sev- 

 eral parallel chain-like groups which, at least between 

 the longitudes of Newhall Pass and the town of Ven- 

 tura, extend in east-west directions. This belt of ranges 

 is apparently enclosed between the two more recti- 

 linear trends of the Santa Ynez and Santa Monica 

 Ranges on the north and the south respectively. 



While the belt as a whole extends in an east-west 

 direction its individual ranges are bent, as if by hori- 

 zontal shifting, into a broad arch with its apex to the 

 north. This curvature is also indicated by the course 

 of the Santa Clara River through the region, as it 

 follows a synclinal valley. 



The contours of these ranges and their horizontal 

 arching in my opinion largely reflect the geologic struc- 

 tures of two different epochs of movement. 



The individual ranges and valleys, mostly structu- 

 ral, consist of narrow-beaded, anticlinal and syncHnal 

 folds respectively. Erosion has been more active in 

 sculpturing these structural folds than in the instance 

 of the Dominguez Range, but both are alike in that 

 the physiography broadly conforms to the structure. 

 It is my present hypothesis that this narrow folding 

 took place in an earlier epoch than the arching, and 

 that originally it had a northwest-southeast direction. 



