The Meaning Of Avebury
The explanation really should be in the word's of its discoverer, Professor Meaden, taken from p22 of his book on the secrets of the Avebury stones:
"Vulva Stone 106 is aligned precisely with both the phallic Obelisk and the sunrise for the early summer May Festival which used to be observed everywhere in Britain. The bearing of 62.5 degrees east of north corresponds to the modern calendar-date of 8 May when the sun appears over the Avebury Hills a mile away. At this moment the rays of the sun cast the phallic shadow of the Obelisk upon the Vulva Stone in a deliberate alignment which bears witness to the seasonal importance of the May Festival 4,500 years ago .... This cosmic union of the stones, caused by the rising sun, expresses in visual terms the idea of fertility ..."
This idea that the neolithic religion centered on the sexual union of the sky Father with the earth Mother is not only visible here at the Vulva Stone, but similar ceremonies were clearly also undertaken at two other major Avebury sites, at the Cove (receiving the male shadow cast by a now missing stone) and at West Kennet Long Barrow (where the sun's shadow shone down into the Goddess' womb represented by the central corridor).
In other words Meaden's ceremony can be seen operating in very similar ways in three separate places at Avebury. I'd say that constituted proof of concept!
Image copyright David Baldwin Night Photography