Yeah, it's a good prog isn't it. Prompted me to look at an old aerial photo of the Chelmer (Springfield) Cursus - same sort of thing there, with evidence of a wooden circle at the top of the cursus and the cursus itself leading down to the river. Suppose you could say there's also something similar happening at Avebury, with the Avenue leading from the Sanctuary to the henge (or the other way, or both).