I'm not sure how you are so confident about your interpretation. Even if we take for granted that stonehenge performed a calendrical function, a purely utilitar

I'm not sure how you are so confident about your interpretation. Even if we take for granted that stonehenge performed a calendrical function, a purely utilitarian explanation seems insufficient. There was no need to drag 25-ton stones around to mark spots on the horizon. The "henge" under discussion in the OP was almost certainly not a calendar, since it was built as a continuous circle: "Oak trunks had been sliced in half and placed snuggly next to each other with the bark side facing outwards. The final effect would have been like a huge tree trunk."