Mussel Rock

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Mussel Rock is a physical feature on the coast of San Mateo County, California, offshore from the city of Daly City. It consists of one large and numerous smaller rocks of a type known as a stack, where a headland is eroded unevenly, leaving small islands.

It is best known for being the closest point to the epicenter of the 1906 San Francisco Earthquake, and where the San Andreas Fault enters the San Francisco Peninsula from the northwest. An additional minor fault, the Mussel Rock Fault, was identified in 2000.

The area above Mussel Rock consists of steep cliffs with frequent landslides, threatening homes in a subdivision above. The adjacent area is a city park.

[edit] Geology

Mussel Rock is a "greenstone assemblage" which is part of the Franciscan Complex, which is the bedrock under San Francisco, and was transported to the site by a subducting plate about 80 or 90 million years ago. It is older than the nearby sedimentary rocks which are part of the Merced Formation, which are about 3 million years old.

[edit] References

Sudran, Dan (2004). Where the Faultline Meets the Coastline (HTML). California Wild: The Magazine of the California Academy of Sciences. Retrieved on 2006-04-26.