On the beach at La Jolla. The sandstone has cylindrical inclusions in the sedimentary layers. At places on the tidal platform you can see series of larger horizontal cylinders emerging from the surrounding rock.
About Bill McCallum
I was born in Australia and came to the United States to pursue a Ph. D. in mathematics at Harvard University, met my wife, and never went back. I am a professor at the University of Arizona, working in number theory and mathematics education.