Ophiolite will not be found in a dictionary of geology before about 1970. Neither will the term "tectonic plate." Both words describe phenomena that only recently have been associated with the theory of plate tectonics, which postulates that land masses and mountains are the result of movement and deformation of massive plates, or segments of the earth's crust, which are literally floating atop the liquid interior of the planet. As molten material flows out of the core from under the oceans it spreads out and away to finally plunge back into the earth's mantle. The downward plunging point is called a subduction zone -- which just happens to be the location of most of the coast of California.

An ophiolite is a sort of tectonic leftover, a sandwich if you will, made up of the lowest layers of seafloor sediments that have been scraped off in the subduction zone to be deposited on land. These tasty geologic tidbits are extremely rare but some geologic gourmand poking around the cliffs of the San Louis Obispo County coast near Point Buchon discovered an unusual layering of augite, analcite, calcic feldspar, and iron oxide minerals, and figured out that they had slid all the way from the mid-Pacific Ocean to the golden coast in something over a hundred million years.

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