(Not rock pile related)
I was just reading an article about Stonehenge [Click here] and they were mentioning that the blue stones had been transported 225 KM from their source in the Preseli mountains and no one knows why, since there were other materials available much closer to the Stonehenge site. Then the article mentions that the blue stones are of rhyolite. Is that correct? In Concord MA where there is no good arrowhead making material, rhyolite is the commonest imported or "exotic" material. Around here anyway, rhyolite was precious. They had to be transporting hunks of it around and trading it etc.This leads to an idle speculation: the use of blue stones at Stonehenge would have represented a huge symbol of wealth - like building doors of gold or walls of bronze. Prehistoric conspicuous consumption. But that is probably wrong, they had metal by then didn't they?