April 14, 2004
The photo above was taken last summer and shows Morro Rock guarding the harbor of Morro Bay, California. This is the westernmost “Morro” of a chain of 14 that form a northwest-trending line between San Luis Obispo and Morro Bay, California. They exist as the remains of domes, plugs, and volcanic necks. Only 7 are popular amongst tourists which call them “The Seven Sisters.”
Morro Rock is between 20 and 27 million years old (Cenozoic Period) and reaches a height of a little over 180 meters (580 feet). What remains is the inner-most part of a once towering volcano. This intrusive structure formed from magma that solidified within the throat of the volcano. Over time the volcano and its underlying 'country' rock eroded and what was left is this highly resistant igneous body.