I have touched on this often before, but I'm intrigued by the manner in which (at Stonehenge, "Bluestonehenge" and Durrington Walls, for example) all indentations in a buried ground surface tend to be interpreted as standing stone sockets or post holes. The default position seems to be that anything that looks like a pit is probably man made. We have argued about the "honeycomb" chalk surface within the stone settings of Stonehenge -- almost invariably interpreted in the literature as a complex of intersecting stone holes indicating a history of uncertainty or changed priorities, with one stone arrangement at a time dismantled and then replaced by another. Another interpretation might be that the taking down of standing stones and their re-positioning elsewhere represents an increasingly sophisticated knowledge of stone alignments as related to the movements of the sun, moon or stars. So the moves are seen as moves towards perfection in the matter of astronomical observations. Others do of course dispute that. My own interpretation is that there was a shortage of stones, so that one setting was replaced by another as the builders of Stonehenge sought to make the best of a rather poor job. But what if some of the pits in the midst of all this chaos are actually extraction pits from which embedded erratic boulders and pillars were taken? Is there any way of telling?
I had an interesting exchange with Nick Snashall on her blog, when I wondered about whether the pits and hollows revealed in the recent Durrington Walls dig might be natural rather than man-made:
Nick — how do you know that these elongated pits are not extraction pits from which elongated large sarsens have been taken, rather than being assumed to be pits dug to receive either standing stones or large posts? When you are removing a large recumbent stone from a field (as I have done) the first thing you do is dig a pit at one end, deep enough to get beneath the stone, so that you can get your levers in. Once you have done that, you can start levering the stone up and out of the recess in which it sits…….. and as you raise the “monolith” bit by bit, you chuck in packing stones or rubble beneath it so that it does not settle back into its original position. You then use your levers wherever you can along the length of the stone, inserting packing stones all the time, until it is clear of the ground. Then you roll it or drag it away.
There is a considerable degree of confidence and certainty in this reply, and I have no way of telling whether this is borne out by the evidence or not. I did have other questions I wanted to raise, but I was too busy with other things. For example, what is this "very distinctive crushing" associated with the removal of large stones from the ground? I have removed large stones with great delicacy, and am not aware that I did any great crushing of the areas on the flanks of the extraction pits.......
Feeding into this discussion is the interesting info from Steve Marshall in his excellent Avebury book, on page 104 -- relating to hollows and crop marks in a field close to North Kennet spring. There are more than a dozen of them, quite prominent, but Steve reports that they have not been excavated. There is a possibility that these "marked sites" still contain buried sarsens -- or they may indeed mark extraction sites from which sarsens have been taken for use in the Avebury stone settings, or more recently for other purposes by the local community.
There has also been speculation about a large "mystery pit" at the centre of Stonehenge, shown up in various excavations. Prof MPP says it is very mysterious, but Tim Daw thinks it is an extraction pit, used for taking away the Lake House meteorite, which he speculates was found here. Why could it not have been an extraction pit once occupied by one of the larger sarsens or even by one or more bluestones?
I agree that a deep hole with vertical sides and maybe less than a metre across is most likely to be a post hole, but exactly what are the criteria used by the archaeologists to distinguish a solution hollow or rill from a monolith socket, or a natural extraction pit from something man-made? I am singularly unimpressed by all this talk about "compressed chalk debris" in a pit being an indicator of a previous standing stone. A natural erratic boulder dumped by a glacier could have very similar compressed material beneath it, although if we find crushed or compressed bone or cremated material in the bed of a pit that would be a different matter.......
Any expert opinions on all of this?