Pacific Coast Geology > Morro Rock and Morro Bay, California by ahochstaedter

Morro Rock marks the entrance to Morro Bay, which is the only harbor between Monterey and Santa Barbara, and is conveniently located halfway between these harbors. Juan Rodriguez Cabrillo named the rock in 1542. Morro is the Spanish term for a turbin or pebble-shaped hill. It has been a well-known coastal landmark ever since. A morro has come to be known as any large rock of this shape occuring near the coast. Wikipedia searches of this term reveals the well-known coastal features in Rio de Janeiro, Brazil.

The rock itself is a beautifully porphoritic ~20 million year old andesite volcanic plug that is much more resistant than the surrounding Franciscan bedrock. It is part of the Nine Sisters volcanic chain that extends from San Luis Obispo to the coast.

Originally, the rock was a sea stack located just off shore. The entrance to the harbor, lying just in front of the rock, is dredged. The strip of land between the power plant on the right and the rock is artificial fill. Today, a road and walking path lead from the harbor to the base of the rock.

Climbing on the rock itself is prohibited to protect Perigrin Falcon nests as well as other birds and wildlife.

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