The stones Nigel mentions below are pretty unconvincing, being rather small compared to the ones lying prone in the field across the road (the field on the map). They’ve got the reddish cast that implies they’ve been underground for a goodly while, whatever that implies.
If you hadn’t read of the contoversy, you’d think ‘blimey these circles have been well and truly wrecked’, and would probably be dissapointed. But if you have read the controversy, and like whodunnits, you could have a whale of a time here, trying to piece the clues together.
One thing I’d add, is that the distribution of the prone stones if unlike that of the natural sarsen drifts on Fyfield down. They seem buried a lot deeper for a start, just barely peeking above the turf for the most part. But that’s just my perception, and even if accurate, is proof of nowt at all.
i think a reddish cast to sarsen stone probably implies that the stone has been red since the dawn of time; water accumulating in and on sarsen stone can colour it red, but this is a fleeting phenomenon since the agent behind the redness is algae. algae is presumably the 'grain of truth' in this folklore that sarsen stones underground turn red: possibly the majority of standing stones at Avebury were either levered out of the ground or had at least one face lying prone and semi-buried in soil for millions of years before they were dragged and erected in their Neolithic positions: it appears to me that the majority of Avebury stones are silvery-grey.