There's actions starting at three World Heritage Sites to attempt to make the host governments conform to the Kyoto protocols arguing that environmental damage is occurring - due to climate change. They seem irretrievably lost. Avebury also appears enormously dry in several images I've studied - those summer droughts may be increasing in the medium term.
Perhaps, Pete, you could take a picture looking down the stone row (Z-stones) over the top of ii or iii, please. I've noticed that the tops of these stones are arranged roughly into a notch (or backsight) shape. I wonder if there's a clear run all the way through - 129 seems to have half-lozenge rebate in the correct place. Everyone seems to take a slantendicular approach to the Z-feature ! ( http://www.themodernantiquarian.com/post/19882 )