It's incredible stuff. firecat turned us on to their product several years ago, and it's been a delight.
I meant to post this photo a few days ago, but it seemed to post with a great big blank space instead.
This morning i spent a great deal of time reading what i could find about the geology of where i was last weekend. We observed caves from the beach and sinkholes close to the bluffs, all clearly caused by the waves working their way into the rock. Apparently it's rather young sandstone, younger than the San Andreas fault, and thus rather friable. The only things written about the sinkholes are (1) danger! danger! and (2) apparently geologists clamber in them to get good looks at how the layers have been folded by the seismic action around here.
This is also posted at http://elainegrey.dreamwidth.org/503879.html .