These are actually not rocks, but natural Asphalt deposits. On a
very hot day you can stand on these and actually leave a slight
Back in the late 1860's T. Wallace More owned a ranch on the mesa above the cliffs. One of the ranch operations was an Asphalt mine. Supposedly, the first paved streets in San Francisco came from Asphalt mined here.
This is only a bit over a mile from my house...I'll likely spend more time on these rocks in the future.
Explore Aug 19th, 2010 #71