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….