Serpentinite of the Coast Range Ophiolite, R. Forest
Ophiolite:
A segment of oceanic crust and mantle that is tectonically exposed on land.
Rock association of the oceanic lithosphere tectonically emplaced on continents by obduction or suturing between colliding continental blocks
A rock sequence that includes deep-sea sedimentary rocks overlying pillow basalt, diabase, gabbro, and peridotite. It represents a fossil fragment of oceanic crust now exposed on land.
Assemblage of rocks thought to represent ocean-floor sediments and the crust and upper mantle beneath them.
(Definition references are listed at the bottom of the Geomorphology Word of the Day home page)
Where in California:
As a result of its lineage as a massive and long-lived tectonic convergence zone delivering and accreting terranes to the western margin of the North American plate, great chunks of ancient stranded oceanic crust can be found (relatively) extensively throughout California.
These ophiolites, and the suite of assembled rocks that comprise the fossilized oceanic floor and mantle accompanying them, are exposed in prominent locations such as the Klamath Mountains (the Josephine Ophiolite and Trinity Ophiolite); the Sierra Nevada (the Smartville Complex, Kings-Kaweah Ophiolite, and the Feather River peridotite); and the Coast Ranges (Coast Range Ophiolite).
