geoblogosphere that Chuck Bailey at W&M Blogs has recently described another such spot in the somewhat more exotic Wadi Jezzi in Oman - Check it out!).
continuation of a blog series I started before the Christmas holidays). When you cross the Golden Gate Bridge headed north, take the Alexander Avenue offramp and follow Conzelman Road onto the headlands. Immediately you are treated with a gorgeous view of the Golden Gate Bridge, but the real story is behind you in the roadcuts. There are ribbon cherts (a form of deep ocean sediment derived from myriads of one-celled creatures called diatoms) lying directly on ocean-floor basalt. Lay your hands on the contact between the two and you are touching the surface of what once was part of the greatest mountain range on planet Earth!
The Marin Headlands region is a stunningly beautiful place with a fascinating geological story. The area is protected as part of the Golden Gate National Recreation Area, which is a level of protection that is more or less equivalent to a national park. It is certainly a popular destination, but it's usually possible to find some quiet corners, especially if you are willing to hike a little. While in the area, don't pass up Muir Woods National Monument. It's one of the most-visited monuments in the country, but wandering through the Redwood forest, it's not hard to see why.