Ramparts and Ditches - the Roman Killing Zone

 Recognizing the Timber Wall and Ditch, predating the more familiar Hadrian’s Wall, highlighted central importance of timber engineering to the Roman army in the field and took this research in an unexpected direction.

While many Roman military installations are identified by their bank and ditch, as archaeological remains they are often somewhat underwhelming, certainly compared with some hill forts, but history attests to their success in withstanding assault.  

The tactics behind these structures can be explored by using a simple SketchUp model of the sort of rampart and ditch described by Caesar[1], which can help illustrate how could a 12' high pile of wood with a ditch in front could stop whole armies.

Forthcoming 2014 Digital Exploration Season; Modelling Stonehenge and Edwin Harness.

Blogging your own research does allow you to preview what is coming up in future posts, and demonstrate despite the long gaps between posts you are still alive and kicking. [1]
My main in 2014 focus will be presenting 3D CAD models of Prehistoric roofed structures using Sketchup.

When I started building CAD Models of archaeological structures in 1990, it would have been quicker to build them in balsawood, and I little dreamt that one day a tool like Sketchup would not only run on a standard desktop, but also be available for free.
At present I am working on several [competing] fronts, with active models of Stonehenge, and an interesting Native American Building at the Edwin Harness Mound. In addition, I hope to do some additional work on Roman Military engineering structures, as well as Neolithic Longhouses should the opportunity arise. The problem that there is so much I have still to publish; among the built environments I have looked at in detail is a Romano British pottery at Orsett and Bronze Age fort which has a huge forge with a smoke bay.  However, as my work on Natïve American architecture demonstrates, you never what opportunities for collaboration may arise.
In this post I want to focus mainly on practical methodologies in 3D modelling of timber structures from archaeological ground plans.

Starting to model Woodhenge in Google SketchUp

The Story so far
Since I decided to blog this research five years ago, one recurrent theme has been my attempts to understand the largest class of prehistoric buildings Class Ei. [1] This includes Durrington Walls, the Sanctuary, Mount Pleasant, Stonehenge, and Woodhenge, the latter being the most interesting as a result of its non-circular plan.
When, as a result of Tim Darvill’s 1996 paper, [1], I first considered Class Ei buildings, I was initially very sceptical of their scale; I had been working on IA roundhouses where there were clear engineering limits, and these appeared to break my rules for timber structures.   
Against this, I began the compilation of a list of characteristics that indicated they were buildings. While the technical insight that resolved this dilemma probably came from studying the engineering of earlier Longhouses, ultimately, progress comes from breaking down your preconceptions by building models that don’t work. I took the unusual step of actually publishing some the models that had not worked in order to demonstrate why it was necessary to create a more complex solution.
It is harder than you might imagine to deduce from the evidence, rather than simply impose ideas on it.

'...when you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth.'
Sherlock Holmes –
The Blanched Soldier, The Case-Book of Sherlock Holmes, Arthur Conan Doyle, 1927

Hadrian's Timber Wall; Reverse engineering a Roman rampart in Google SketchUp

Caesar’s account of the war in Gaul contain over forty references to ramparts, some native, but mostly those built of timber with a ditch in front constructed by his army in the field. [1] I have argued that the three lines of double postholes with a ditch in front to the north of Hadrian Wall represent such a rampart.

Recently, I have been trying out Google SketchUp as tool to explore the engineering of this structure, and express structural ideas visually.  In a previous article I have discussed the issues of visual representations of the past, as distinct from models and diagrams.

CAD and the Archaeology of postholes

I bought my first CAD system in 1990, using it for my work in Essex, and subsequently offered my services to all the archaeological units and trusts working in England at the time; there were no takers.

However, I had also realised that as a tool in my attempts to understand the evidence of prehistoric posthole structures, CAD was not yet the answer.  It was not just that it was slow, a 486DX 25 MHz computer running at would take 12 hours to print a shaded view, but even more critically, putting a cone on cylinder and calling it a roundhouse did not advance my understanding, it was simply an aid to drawing more accurate ‘artistic’ reconstructions.