Blog Keiller cuttings

Pinning down the Keiller Cuttings – Part 3 (scheming and plotting)

This blog post is part of a series: read Part 1 here, and read Part 2 here.

I have a confession. Much as I admire his surveying chops, Keiller’s approach to numbering and labelling (stones, cuttings, whatever) leaves me sobbing.

Let me give you a flavour of what I mean. In an earlier post I mentioned that he liked to re-use letter codes for reference points and survey datums/stations. Taking 1934 as an example, ‘A’ and ‘B’ could refer to the mid and end point of the original line he surveyed running across the axis of the Avenue line or the points where the baselines bounding his 80’ wide corridor intersected the fence at the southernmost end of Mr. Peake-Garland’s Waden Hill Field. Take a look at the drawing below from the plotting book and you will see what I mean.

Where the survey blocks met the southernmost fence line crossing the field

But the real fun has yet to start. He numbered his individual 100 x 80’ survey blocks from south to north, using Roman numerals – I, II, III, IV etc… Each of these blocks in turn contained a total of sixteen 25 x 20’ sub-cuttings – four rows of four. The individual sub-cuttings were given Arabic numbers – also incrementing from south to north – and always indicated in superscript. To differentiate between the two rows of cuttings that ran up either side of the line of 100 x 80’ blocks – i.e. that theoretically tracked the lines of paired megaliths – he used L (Left) and R (Right). However, in deciding which side was Right and which Left, instead of facing north towards Avebury, he faced South, away from it. So… the 3rd cutting of the fourth block on the western side of the Avenue would be sub-cutting IV3R. Its partner on the eastern side would be IV3L. As for the two rows of 25 x 20’ cuttings running down the centre of the Avenue line Keiller added a C to indicate that a given code referred to a central sub-cutting (e.g IV3RC and IV3LC). It was so overwrought that the plotting book included a dedicated diagram to demystify it (see below). 

The key to Keiller’s labelling schema

And it gets worse. Keiller gave the corners of each 100 x 80’ block a letter code, moving up through the alphabet from south to north. The diagram I have sketched out below should hopefully clarify.

codes and datums everywhere

In his descriptions and in plotting book diagrams, the corners of the subdivisions of the cuttings are labelled with respect to these corner designations. So the 2nd sub-cutting on the ‘Right’ hand side of block VI would be designated VI2R and its corner points (moving clockwise) K1, K2, K2L and K1L. Take a look at the subdivision plan below (more on subdivisions and extensions in the next post) and you will get a sense of the complexity that is piling up – and this is just in laying out the trenches.

labelling the sub-cuttings

My final note on the coding relates to the individual standing stones themselves. Here Keiller took a refreshingly simple approach. Each megalith had its own number, starting at the southern extent of his excavation area with standing stone 1 and then incrementing as he moved northwards towards Avebury. So, the southernmost stone pair in Waden Hill Field = stones 1 and 2. The next pair to the north 3 and 4, and so on. Odd numbers on the Right (western) side, even numbers on the Left (eastern) side.

When Isobel Smith produced her synthetic publication of the Avenue excavations, she renumbered. Instead of individual megaliths, she numbered stone pairs (using A to indicate Left and B to indicate Right). She also flipped the numbering strategy on its head, starting at Avebury with Pair 1 and incrementing as one moves south. The logic was faultless: there were undoubtedly more stones waiting to be discovered to the south of Keiller’s Pair 1 and 2, and her approach allowed meaningful numbers to be assigned to them. Irony is in the eye of the beholder, but for me it did add a layer of complexity to what was probably Keiller’s least torturous schema.

That’s me done for now. In the next post we will look at what Keiller did when things did not go to plan (no pun intended).

Read Part 4 of this series by clicking here.

Blog Keiller cuttings

Pinning down the Keiller Cuttings – Part 2 (Keiller makes a point)

Plotting out the excavation cuttings (a work very much in progress)

Last week Mark shared Part 1 of this series – read it here first.

Next step is to recreate Keiller’s excavation grid using the step-by-step measurements and drawings in his 1934-5 Plotting Book. I could have taken a digital approach from the outset, but to limber up, and better understand how the grid of planned excavation cuttings slowly unfolded on the 10th of April 1934, I began by hand-plotting his measurements, to scale, on a sheet of drawing film.

It all began for Keiller with the setting up of a point on the central axis of the Avenue line. The focus of the 1934 excavation was Mr. Peake-Garland’s main Waden Hill field; a strip running north-south alongside the road linking Avebury to West Kennett. Keiller started by establishing a centre line along the main axis of the Avenue at the southernmost end of the field, where 11 surviving stones could be seen (9 fallen and 2 still standing as a pair). He used a tape to measure the midpoint between the southernmost duo of fallen stones (37A and 37B using Smith’s numbering scheme) and did the same between the surviving upright stones 33A and 33B. He then joined the dots to create a notional line running down the centre of the Avenue and established a reference point (labelled A) on this line.

Keiller’s cuttings 1, 2, and 3, showing points A, B, C, D, E, F, G and H along West Kennet Avenue. A page from the 1934 plotting book, accession number 78510469 at the Alexander Keiller Museum.

Using a theodolite the next step was to set out two points perpendicular to A and at a distance of 40’ (12.19m) to the approximate east (C) and west (B) respectively. These points marked the east and westernmost extensions of the grid needed to encompass the width of the Avenue line. So far so good. Using this line of 3 points as a reference, Keiller then set out an 80’ (24.38m) wide corridor running to the northwest towards Avebury. This corridor was subdivided along its length into a series of numbered 100’ x 80’ (30.48 x 24.38m) blocks which were in turn subdivided into parallel lines of 25’ by 20’ (7.62 x 6.09m) cuttings designed to capture the locations of Avenue stones (more on the rather idiosyncratic coding of these blocks and sub-divisions in the next post).

What Keiller and his team had achieved with a theodolite and 100’ survey chains, I was mirroring using a sharp pencil, drawing film and graph paper; working page by page through the plotting book…

Click here to read Part 3.

Blog Keiller cuttings

Pinning Down the Keiller Cuttings – Part 1

One of the most vexing challenges in relation to the Keiller excavation archive relates to the precise locations of the trenches his team excavated – what he termed ‘cuttings’. One of the goals of the project is to create a series of georeferenced digital trench plans for each of the years of excavation. As to why, once in place these will enable us to spatially locate and anchor the various finds uncovered, photographs taken and pithy asides scribbled in the dig records and diaries.

We certainly have the re-erected stones and concrete markers resulting from the excavation trenches, but as to the precise areas that were investigated around these we are in the dark. As for the published trench plans, experience from previous attempts to fix these to the current Ordnance Survey base mapping for the area revealed significant levels of artistic licence and generalisation that precluded any neat fit. 

As a result, the decision was taken to go back to Keiller’s original survey records and start from scratch – using the digital equivalent of 100’ survey chains and theodolites in order to lay out his trenches afresh. This meant working methodically through the 1934-5 Plotting Book which contains highly detailed scale drawings alongside a narrative account of the work carried out. More of this to come in later blogposts, but a number of issues rapidly became clear. 

First, Keiller was a confident and accomplished surveyor, and you can very quickly see why his surveying skills earned the respect of Mortimer Wheeler. 

Second, he was obsessive with regard to formality and precision – rectangles, triangles and parallelograms abound. If a cutting needed to be extended to capture the full extent of a feature, it was not enough to simply extend until the feature had been revealed (and then tidy up and record the resultant extension). Oh no. Instead meticulously surveyed extensions were laid out in order to facilitate this search, and if the full extent was not revealed a second stage of meticulous survey was carried out to further extend.

Third, and building upon the point above, for Keiller the laying out of trenches was an end in itself (meticulously surveyed and geometrically perfect) rather than a means to an end (a framework for the excavation).  

Fourth, for all of the above he was remarkably lax in some regards. For example, the baselines setup in 1934 to lay out the cuttings along the line of the West Kennet Avenue were basically floating. They were established in relation to extant pairs of stones that were not themselves surveyed in position prior to the survey. Needless to say these stones were subsequently relocated and set into concrete as a consequence of the excavation and restoration work. He also had a habit of re-using codes to indicate reference points on his cutting grid. 

So, with pencil, permatrace, mouse and GIS in hand, it was time to go back to early April 1934 and begin to follow Keiller in laying out the first of the Avebury cuttings…. 

Read more in Part 2!