On a trip from Santa Cruz to Half-Moon Bay along Highway 1 last weekend we stopped at a little parking lot. I think it was called "Bean Hollow State Park" or something like that. Walking around I suddenly discovered these amazing structures in the sandstone. Later a work colleague told me that these structures are called "Tafoni" and they are supposedly created by wind erosion, not by water as you would expect that close to the ocean. If you do a Web search on Tafoni you can find other sites with photos of such structures, often far inland... The bird studying the rock is a cormorant, by the way.

Click on a thumbnail picture to see a larger photo.