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Map Satellite This volcanic area lies immediately to the north of the San Andreas Fault. It is composed of light gray to pink rhyolitic felsite with some andesite and tuff interspersed. It has been dated to the Oligocene but may date as late as mid-Miocene. The corresponding flow on the south side of the fault has moved 304 kilometers (190 miles) north-northwest and is a principal component of the Pinnacles National Monument. Within the area the topography ranges from rather rugged slopes to relatively smooth, rounded hills, though in general the area is highly convoluted. The dominant vegetation is grassland with oak, Quercus spp. Integrity: The area is grazed and there are ranch buildings as well as several mines. There also are some jeep trails in the area. Use: Private Ref: Matthews, Vincent, 1973. Pinnacles-Neenach Correlation, Geol. Soc. Amer. Bull. No. 84, pp. 683-688. January 1977
Inventory of California Natural Areas
Revision © 2008 Steven Louis Hartman
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