Geology of a Portion of the Santa Monica Mountains

Citation

Peterson, Raymond Alfred (1931) Geology of a Portion of the Santa Monica Mountains. Bachelor's thesis, California Institute of Technology. doi:10.7907/1Q7M-3129. https://resolver.caltech.edu/CaltechTHESIS:12022009-112321773

Abstract

The area discussed in this report lies on the north side of the Santa Monica Mountains, bordering on the San Fernando Valley. It includes the region around the Encino Country Club and Encino Reservoir, and extends from Ventura Boulevard on the North to a short distance south of Mulholland Highway. The accompanying sketch map shows the location of the area, and its relation to the major features of Southern California. It is easily accessible from Los Angeles or Pasadena by Ventura Boulevard or Mulholland Highway.

Very excellent Los Angeles County maps (2,000 feet to the inch, 25 ft. C.I.) are available for the region, in the form of the U.S.G.S. Van Nuys and Reseda quadrangles. Fairchild Aerial Surveys of Los Angeles have also made a mosaic aerial map of this locality and the remainder of the Santa Monica. Mountains. The mapping for this report was done entirely on the aerial map, which proved highly satisfactory, allowing contacts and other features to be located very accurately. The scale used was 1500 feet to the inch.

Mapping was made difficult by several features. Most of the region is covered by very heavy brush, which is all but impassable. Accurate mapping is very slow and laborious. In the valley north of the Encino Country Club, contact and exposures are largely covered by alluvium, making exact mapping impossible. Also this fact coupled with the similarity in lithology between parts of the Modelo and Topanga formations makes it difficult to find the Modelo-Topanga contact. One helpful feature is that the Modelo is usually free from brush and covered by grass, which greatly facilitates mapping. An attempt was made to map a small area accurately rather than a larger one roughly. Hence the map represents only an area about three miles square, and of this the mapping west of the eastern border of the Encino Reservoir by Holzman. Also the mapping of the Modelo-Topanga contact was done jointly with Holzman.

Part of this area was included in Kew' s report, U.S.G.S. Bul. 753. Also the area is included in Hoot's report on the Santa Monica Mountains, now in press as a U.S.G.S. bulletin. The mapping of this report seems to agree in larger details with that of Hoots, but differs slightly from that of Kew as brought out later. This area overlaps in part that covered in Scharf's Senior Thesis. The area to the west has been mapped by Holzman, and that south by Crossman.

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