Saturday, December 29, 2012
The southerly hook of Point Reyes forms Drakes Bay (after Sir Francis). Drakes Beach lies along its northern shore and is an elegant curve of high bluffs, broken by a few small barriers and a couple of larger spits.
I believe the bluffs are Miocene siltstones and sandstones of the Purisma Formation. There is a wonderful planed-off platform at the base of the cliffs. Wave-cut platforms - shore platforms, more generally - have generated plenty of research and speculation. I suspect this one reflects some combination of modern waves, historic uplift?, and lithologic variation - but that's mainly a guess. The sun was setting and we had to get back to the city for dinner - so much for more exploration.