. Bulletin. Science. 16 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Potrero Rd |l Sherwood | Westlake Blvd^/ 1 mi Undero/"""— Canyon/ R$l/ /Fig. 1B Thousand Oaks Blvd !ihv Lake L/Hindero /Kanan / Rd WESTLAKE VILLAGE Lad^face Mtn. 1 1km '. Q a | I Quaternary alluvium T m Iv^N Monterey Formation Lindero Canyon T t u c - Upper Topanga Formation Tcva Conejo Volcanics mi km Fig. 1. Maps of the study area in the City of Westlake Village, Los Angeles County. A. Location map. Position of Fig. IB outlined. B. Geologic map after Dibblee and Ehrenspeck (1993a). The "X" indica
. Bulletin. Science. 16 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Potrero Rd |l Sherwood | Westlake Blvd^/ 1 mi Undero/"""— Canyon/ R$l/ /Fig. 1B Thousand Oaks Blvd !ihv Lake L/Hindero /Kanan / Rd WESTLAKE VILLAGE Lad^face Mtn. 1 1km '. Q a | I Quaternary alluvium T m Iv^N Monterey Formation Lindero Canyon T t u c - Upper Topanga Formation Tcva Conejo Volcanics mi km Fig. 1. Maps of the study area in the City of Westlake Village, Los Angeles County. A. Location map. Position of Fig. IB outlined. B. Geologic map after Dibblee and Ehrenspeck (1993a). The "X" indicates the fossil wood site. exposed across a 100-m2 area along the southern flank of the ridge (Fig. IB). Two broken logs were found encased in the tuff unit southwest of the ridge. This concentration of middle Miocene fossil wood may not be unique to the area. Local residents have reported that reworked fossil wood occurs throughout the Thousand Oaks region in the upper Conejo Volcanics and overlying Upper To- panga and Monterey Formations. [Note: The stratigraphic nomenclature of Dib- blee and Ehrenspeck (1993a) is used here; Yerkes and Campbell (1979) refer to the latter two formations as the Calabasas and Modelo Formations respectively.] Geologic Environment The Conejo Volcanics lie between the Lower Topanga and Upper Topanga Formations (Dibblee and Ehrenspeck 1993a; Fig. 2) and include up to 2 km of extrusive basaltic flow breccias, flow and pillow lavas, andesite and tuff breccias, dacite breccias, and a variety of intrusive forms that have been described by Dibblee and Ehrenspeck (1993b). The lower portions of the volcanic sequence were formed in a marine environment, indicated by an abundance of pillow lavas, pillow breccias, and occasional layers of fossil oyster debris. Higher in the se- quence, the rocks were deposited in a subaerial environment and include laharic breccias, fluvial and alluvial fan breccia-conglomerates, volcanic bombs (Dibblee and Ehrenspeck 1993b)
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