I love San Francisco. I really do. I’m not really much of a big city kind of girl, but San Francisco is one of the few big cities where I would willingly live. Except that it’s really, really expensive. And hilly. Ask my calves.

Of course, what other picture could I use to lead off my memoir of San Francisco:

I took that picture from the Marin Headlands on the north side of the Golden Gate Bridge. I don’t know why, but I love this bridge. I say I don’t know why because I am deathly afraid of heights. And I hate, hate, hate bridges.

But I love this bridge. I could spend hours just looking at it. Taking pictures of it.

Watching ships pass under it.

Looking at it from different angles.

And in different weather.

I don’t even mind driving over it, although I’m not sure I could walk over it. Spending that much time on it might be a bit too much.

Here’s a bridge I don’t like:

That’s the Oakland Bay Bridge. As much as I love the Golden Gate Bridge, I hate the Bay Bridge. I’m terrified of it. I will (and did) drive several hours of my way to avoid crossing it. And I know why. It’s because it broke in the Loma Prieta earthquake. So I already don’t like bridges, and then it breaks. So there is no way in hell I’m going to cross it if I can help it.

Ok on to better things!

While out at the Marin Headlands, I walked out to the Point Bonita Lighthouse. Sort of. You can’t currently get all the way out to the lighthouse because the suspension walking bridge to it is closed because it’s falling apart. But that’s ok, but the photo ops at the spot you can get to are just gorgeous.

Here’s a view of the lighthouse from a point called Hawk Hill, of which there will be pictures later.

Same view, zoomed out.

The trail to the lighthouse involves going through this unlit and low ceilinged tunnel.

But then you get there and see this.

And this.

And this.

And this.

And this.

And these. (Those are harbor seals.)

So back up to Hawk Hill.

This is Hawk Hill from Point Bonita. In addition to the great views of the Golden Gate Bridge, there’s a little bit of geology!

These are layers of ribbon chert, part of the Franciscan formation. These are the remains of millions and millions of radiolaria, tiny organisms that produce skeletons of silica. When they die, those skeletons fall to the bottom and pile up over many, many years.

Between about 130 million years ago and 30 million years ago, before the San Andreas fault existed, the coast of California was a subduction zone. While the Pacific plate was diving under the North American plate, parts of the Pacific seafloor got scraped off and crumpled up into an accretionary wedge. This and some other rocks are the Franciscan complex, which makes up a large portion of the ground around San Francisco.

Above the tilted layers of chert, there’s this nice layer of sediment. So this obviously wasn’t hanging out way above San Francisco Bay its whole life. In fact, the bay used to be much, much smaller than it currently is. During the ice age, sea levels were much lower and the bay area was mostly a dry valley through which the Sacramento and San Joaquin rivers ran on their way out to sea. So it’s easy to imagine that all these water-worn rocks came tumbling down those rivers and settled out on this area that eventually got uplifted to a site that gives you beautiful views of San Francisco.

This location also contains the remnants of what was to be a big gun placement during World War II, and there are a couple tunnels you can walk through.

I found a couple examples of slickensides in some of the rocks around the entrances to these tunnels.

More to come!

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