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Think this is the best tunnel yet.

Great lighting, I like seeing new pictures of this place.

Sweet storm drain. Any clue how old it is? What kind of rock is it through?

Posted by Herm Sweet storm drain. Any clue how old it is? What kind of rock is it through?

It was built shortly after the 1906 earthquake. It used to dump sewage right to the ocean, but now it's just an emergency overflow.

I don't know the exact rock, but according to the maps it's some kind of "Pre-Quarternary deposits and bedrock".

Posted by romainpp It was built shortly after the 1906 earthquake. It used to dump sewage right to the ocean, but now it's just an emergency overflow. I don't know the exact rock, but according to the maps it's some kind of "Pre-Quarternary deposits and bedrock".

Yes exactly! ^^