Tuesday, 10 July 2012

Stone 56 - The Proof Its Position Is Correct

There is a consensus that Stone 56 (the tallest one) was re-erected by Gowland in 1901 in the wrong place. Alexander Thom stated it was 60cm out of its original position which Mike Parker Pearson in his recent book dismissed and claimed it is just 30cm out.

As far as I can tell this belief is because the stone is twisted and not symmetrical within the inner horseshoe. Most writers, and many plans, assume this symmetry was meant to be and dismiss the imperfection as a mistake.

I don't think it is a mistake, I think it is deliberate and has meaning. But before I develop that idea further I need to show why I think Gowland re-erected the stone in its original position.

Gowland wasn't just a skilled engineer he had also excavated hundreds of Japanese archaeological sites; he was familiar with archaeological digging.
Reading his report it is obvious he was methodical and careful, and he included detailed plans of his excavations.

I have collected relevant sections of his plans in this diagram.

(Please click on the diagram to expand it)

The method used to raise stone 56 from its precarious leaning position was to dig behind it in three sections. Each section was cleared individually and concrete used to reform the back stop before the next section was started. As can be seen the original back wall of the hole could be clearly seen and with the adjacent section undug it was easy to create a new concrete back wall in the correct place.

The front section was not dug until the stone had been raised so preventing it moving forward. The stone pivoted on its base and as can be seen and measured in the plans accompanying this post, it returned to being against the original position of the back wall of its hole. Because of the pointed nature of the bottom of the stone it was necessary for the stone to be corrected from the side with hydraulic jacks once upright, showing again the care he took to replace it in its original position.

There may be a centimetre or two difference in position arising from imprecision of excavation but unless evidence can be produced that contradicts the excavation report it is incorrect to say that Stone 56 is not in its original position.


  1. It's an interesting idea that that the latest research may be wrong: Who is the consensus between?

    In this type of ground, when a stone starts to lean, it's base forms a cantilever effect: In essence the ground away from the leaning side provides some lateral restraint. The centre of gravity is repositioned to the leaning side and this is combined with any counter-restraint lateral forces (giving a combined force component, on the leaning side, going down into the chalk bed).

    The lateral restraint away from the lean results in lateral stresses within the ground: The ground away from the leaning side then compresses or deforms to absorb the force (thus allowing the stone to rotate and shift in position). Chalk tends to deform little in vertical compression. However, infill or weathered chalk is much more susceptible to lateral deformation.

    When such a stone is raised, even if it were to be raised against structural blocks, the shift in location of the toe would already have occurred.

    I wouldn't discount statements that the stone is not in its original position: I suspect that this has been properly researched.

  2. Many thanks. That is a very good point and an extreme example of it can be seen with stone 55 where the heel skidded out of the hole backwards as the stone fell. One point I should have mentioned is that on the leaning side at an early stage a very large hole was dug and refilled in addition to the sloped hole that the stone was erected by. The ground was much looser on that side and Gowland exposed the solid chalk back wall of the hole so in this case I don't think the heel moved backwards in the hole appreciably.

  3. Possibly, but from seeing an exposure of the back wall you would not necessarily know if there has been a lateral shear plane failure behind (and below) the back-wall of the pit. The hole may originally have been over-dug and fill compressed out.

    I would imagine that, with the statement of 12" from MPP, there will be some sort of analysis to come forth in due course?

  4. Look at the position of the toe of the stone, relative to the horizontal strata above. The stone had clearly nosed to the south west – pushing its base forward under those layers, hence it was further forward than when first set before it was winched upright again by Hawley. OK they slumped too, but disturbed chalk bedrock degrades, even at depth, and Hawley says he could tell where the solid chalk began within the original construction cut. The stone is certainly more than a few centimetres out of place.