Neenach Volcano is an extinct Miocene volcano in the Coastal Ranges of California. The volcano was split by a fault in the San Andreas fault system and over the last 23 million years the two halves of the volcano have moved about 200 miles apart.
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The original volcano formed about 23 million years ago. It formed along a fault in the San Andreas fault system. Through tectonic plate motion the western half of the volcano moved north at about 1.5cm per year. During the course of this movement the volcano also eroded away to the minor formations visible today.
Pinnacles
The remnants of the western portion of the volcano lie in Pinnacles National Park (36°29′55.44″N 121°12′9.02″W).
Neenach
The remnants of the eastern portion of the volcano lie about 200 miles south of the western portion near Neenach, California (34°44′58.30″N 118°35′51.62″W).