Was a pleasant surprise alright, just climbed onto the boulder to get a better view of the fields while looking for the other panels and noticed the basin. Rings on the top surface didn't show up until I used hefty flash.

The bad news is the other panels, one of which is really nice, seem to have become overgrown with turf or are now part of the piles of field clearance among the fields. Should be able to confirm that this panel is new next week at the WAC.