Ok everyone calm down here a minute - not that all these ideas aren't interesting. But, well i'm an archaeologist. And I can tell you there are absolutely no faces carved on those stone. I can also tell you that there are megalithic sites like this all over Europe, Britain and Ireland. (Check these ones out
http://en.wikipedia.org/wiki/Callanish_Stones http://en.wikipedia.org/wiki/Ring_of_Brodgar two nice Scottish ones for you). They are the quintessential element of Bronze Age architecture.
As for the stones themselves, well they came from Wales. It's a fair distance away. But people make the mistake of thinking that people were somehow primitive or untechnological in the past. This is not the case. In fact all it really takes is a bit of hierarchy and some man-power - there was plenty of that in the bronze age. So it's not a great mystery. Hard work, yes. But not unexplained.
The positioning of circles in the landscape is likely to do with visibility to and from, and a clear view of the sky - we do very fun landscape studies which allow us to simulate the archaeolandscape and 'fly through' and play with viewsheds and what not. Not sure about the Glacial aspect, but then if you've been to the British Isles you'll see they are very much up and down - anything glaciated is lower and flatter. Area's like that are also associated with water at this period in time due to the very different and more temperate climate.
The stones do have a rather impressive strong cosmological aspect which is undisputed. But why not? Do you have a clock or a calendar? Bronze Age people needed to keep track of the time too.
In a more generalised point, beware of popularised accounts of archaeology. Often they are guff. Still, the public interest keeps us in a job. But there's a funny archaeology cartoon which unfortunately I can't find a link to... It shows two blokes (Iron Age to be precise) chatting to each other. One says to the other "that brooch you have on, with the intricate metalwork and enamel design depicting a boar eating a snake...what does it MEAN?". And the other bloke says "I dunno, but it holds my trousers up"