>>at Skara Brae, for example, that patently does not
>>apply; the reason it does not apply is due to the readily available building material - ie stone not >>timber

Thats a good example but I think it also adds only more weight to the ritual motivations. Why would they do the same all across the UK and Ireland if the resources were different in each place? In a place with lots of timber it would make sense to use that, and in places where stone is plentiful and no timber, they would use stone. Why then is the general construction the same across such wide areas?
>>Do you know when and for what reason the last sarsen erratics were taken from Piggledene, >>just outside the great stone circle and Avenues at Avebury? Well, it wasn't a few thousand ago, >>it was actually about a hundred years ago to supply the sleepers for the tramlines in Swindon >> (material required, site located :-)

Thats a very practical use of resources considering the task, using large boulders instead of dry stone wall is not nearly as efficient or practical for holding animals, thats just overkill and considering the premise of the theory that they were built for practical use... It would be like using napalm to keep your grass short.

>>Again I hear what your saying but what springs to mind are the hundreds and hundreds of miles >>of dry-stone walls you'll see in the Lake District and the Yorkshire Dales - now there's a lot of >>backbreaking work if ever I saw it and I wonder why they used stone and not wood or planted >>hedges?

Stone walls are back breaking to make but I think they are also a vastly more efficient use of labour and stone, as I said in last post, than moving massive stones over distances. One man can gather and lay stones for dry stone walls but moving those large stones takes several men to make a smaller enclosure in more time.

Apart from that, if you look back to the first circles, the boulder kerbs of passage tombs in Sligo, they enclosed a likely burial chamber, then you get a large cairn filled circle at Beltany tops in Donegal, then more refined smaller circles with less stones and more practical to make still enclosing a mound at Ballynoe in NI, then 'small community' rings in Cork/Kerry that a dozen or more people can make. It seems a logical evolution of the form if the chronology is correct. I think it follows pretty much Burls book but he also factors in the Scottish influence in Cork/Kerry with the small cairns sometimes outside the circle unlike Scotland, then we also have boulder burials in the centre of medium sized circles and not forgetting the tiny five stone circles that would hardly house more than a single dog.

On balance the evidence shows that a high proportion have features of ritual 'by the book' building, the carefully selected locations (and levelling of sloped land), and widespread use with regional variations, if we know a large number had at least some features of ritual use, and add up all the the different features found on every ring showing them, then it pretty much spells out that the general form is ritual.

For example if an alien gathered one note from every currency in the world and found at least one security feature on most notes, like UV inhibiters on one, magnetic ink on the other, watermarks on yet more, then the alien could pretty much say that notes in general have security features. If they all on the other hand only had UV inhibitors then it could mean bank notes have security features or it could mean the material used had a UV inhibiting property that the makers were un-aware of or didn't think significant. The different techniques employed across the range of notes is the clincher, just like in circles, some have cairns inside/outside, some have boulder burial inside, some have associated standing stones or rows, some have cup marked stones and then you have the tiny five and four stones of no practical value for enclosing pretty much anything. All adds up to a general picture of ritual use.