That hole just doesn`t look right to me, considering that stone 27 would have to have been precisely placed to be in the correct alignment to stones 26 and 28.
I`m very surprised to see that the base of both the stone and hole are sloping. The outside of the circle is to right of the diagram and that`s the side it seems that the stone entered from. If the stone was tipped in, then I would have expected it to land further to the left and have to be manoeuvred to the right while in an upright position.
I would expect the weathered soil to be a later ingress into the hole.
baz
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