The super-fluffy very light green stuff that you can just barely make out in the branches in the foreground is "grandfather's beard." It's sort of like fluffier, bright green Spanish moss, and it only grows where there is 98% pure (or better) air. So. We breathed some healthy air that day. (For the record, after guide #1 provided us the kumbaya/commune with nature moment of that fact, guide #2 exclaimed "Oh, man. I burn the hell out of that stuff. It's a great fire-starter--it even lights when it's wet!")