Posthole Archaeology; Function, Form and Fighting

In the previous post I posed the question what buildings does a moderately complex hierarchical agricultural society require, looking at aspects of agricultural buildings; this time I am looking at moderately complex hierarchical society, or at least that end of hierarchy that tends to represented in archaeology.
It is fashionable, and perhaps progressive, to talk of higher status individuals or elites, to avoid cultural bias inherent such terms as aristocracy.   However, I use the term in its original cultural context precisely to reference that bias, or understanding, and also is to imply a degree of continuity between Prehistory and History.
I am going to look particularly at the Late Iron Age fort at Orsett, Essex, [1] now lost to the latest incarnation of the junction it guarded 2000 years ago. [below].  It typifies all the problems of interpretation associated with archaeology that has been ploughed. It was clearly a fortification at some stage, and only the aristocracy, have the resources, interest and right to build such things. Systematic and sustained fighting, takes considerable resources, training and expensive kit. It was after all, what maintained them at the top of the divinely sanctioned heap, and some might argue it was their raison d’etre.

The Orsett "Cock" Roundabout looking South; A13 crossed by A128.

Archaeology is often uncomfortable with this notion of class, it plays havoc with the simplistic way we view the distribution of material culture, especially since historically, our masters have often had a different origin from the rest of us.
In all the arts, including architecture and war, the aristocracy are over represented, since these things define the nature of their culture, and reinforce their essential otherness from ordinary people.

Throughout all Gaul there are two orders of those men who are of any rank and dignity [Nobles and Druids]: for the commonality is held almost in the condition of slaves, and dares to undertake nothing of itself, and is admitted to no deliberation. The greater part, when they are pressed either by debt, or the large amount of their tributes, or the oppression of the more powerful, give themselves up in vassalage to the nobles, who possess over them the same rights without exception as masters over their slaves.

Julius Caesar;The Gallic Wars, book VI, chapter 13 [2]

The cache of Iron Age Spearheads from the Slighted defences of the Orsett Fort.

The Warring Class

The History of Britain, at least until 17^th or 18^th centuries, is an account of a violent and often internecine dispute between the ruling families of the country for control of its wealth, part of wider pattern involving Western Europe and beyond.  While it might be somehow satisfying to put this grim historical narrative down to the advent of Latin or Christianity, in reality, one has to presume similar processes were happening in ‘prehistory’.
Historically, we can find a narrative thread that links and explains these processes, but this makes no sense in terms of the data that archaeology deals with; it is far to complex. Consider 1066; on January 5th the English king Edward the Confessor [left [3]] died childless, and Harold Godwinson, the earl of Wessex, seized the throne of England, prompting two foreign invasions; against the odds he defeats and kills King Harald Hardrada of Norway, only to be killed himself by William the Bastard, Duke of Normandy, on October 14th at the Battle of Hastings.  One of the largest and richest countries in Europe, with a population of at least 1.5 million, had been taken over with an army of less than 10,000, and now had a Norman French Duke as King,  its 3^rd head of state in a year.

The point of this simplistic account is to illustrate that archaeology is too crude a tool to grapple the movements and activities of an aristocracy, who are responsible for many of the more exceptional archaeological remains we find.  A thousand years earlier, they had faced a catastrophe, as the Roman aristocracy inserted their army into politics of Western Europe.  

Fighting the Fight

It might be argued the Roman army was developed in part as response to the style of warfare practiced by the “Celtic” tribes to their north.  Their systematic approach took full advantage of the practicalities of iron in the design of their arms and armour, coupled with superb military engineering and ballistics which overturned the certainties of centuries of warfare.

The excavation at Orsett showing all features and others dotted in from areal photographs, compared for scale with St James Park Newcastle[4].

With the benefit of hindsight, the small fort at Orsett was never going stop a Roman Army, but most groups put up a fight, it was what you did, although only the most foolhardy did it more than once.

Orsett Enclosures visible on an areal photograph prior to their excavation [left] and subsequent destruction under modern network [right]; looking South.

The Late Iron a Age site at Orsett [Cock], a site named after the pub in more innocent times before the advent of the search engine, although it was tempting fate even then.   It is now the Orsett Cock Roundabout, which occasionally makes a guest appearance in the Essex traffic news.

It is a typical British archaeological site, defined by large enclosure ditches discovered by aerial photography and subsequently threatened with destruction by development.

The response [then as now] was to mount a rescue excavation; "rescue" is an important concept, conveying an element of underfunded last ditched desperation typical of these projects.  As usual, the excavation team then dispersed, leaving the site director to write a brief interim report, before he left archaeology. [5] The resulting drawings, photographs , context cards and finds then languished for a while with Essex County council, adding to national backlog of unpublished excavations; rescuing always takes priority, and there is no shortage of archaeology being destroyed.   The pottery was part processed, and swamped by the products of four [known] Romano British pottery kilns.   Not untypically, there were problems with specialist reports, the teeth and bone had been lost along with other finds on route to a specialist. 

But there is actually a much deeper problem with Orsett; this sort of site is easy to excavate but difficult to understand, and report on, presenting some of most complex interpretive puzzles in archaeology.  

Unknown unknowns; super-complex archaeology.

While deep stratified urban archaeology is infinity more challenging to excavate, it can be easier to interpret precisely because it has stratigraphy which gives a chronological sequence around which an understanding and relationships can be built.  The site at Orsett is typical of a ploughed rural site:`

• Plough reduced – no stratigraphy;
• Large areas of site damaged/ obliterated;
• Parts of site not available;
• Concentration on main crop mark;
• Most of the features are postholes.

An all features site plan of Orsett site showing the limited sample available for study.

Conventional dating with pottery or radiocarbon does not really apply to postholes, and without stratigraphy there are no real relationships.  Another important consideration is alignment; certain periods tend to have similarly aligned structures, which, if you can find them, can be a useful observation. 

The sites largest features, the ditches, have to form something of a spine for understanding as they do have some stratigraphic relationships, and lots of pottery which was probably deposited deliberately. However, the ditches are also part of the problem, because they were mostly a single phase event that destroyed an unknown number of earlier features including  boundaries. Since the “site” is defined by the ditches, the extent and nature of surrounding archaeology is yet another unknown. Usually, these larger ditches are not fully excavated, and in addition, it is often difficult to detect small features like postholes dug into this type of context.

Numerically, postholes are main type of evidence; of the 1300 features recorded there were 780 postholes and 100 stake holes, only  about 30 were clearly associated with the main roundhouse. [Left; a typical 10m square of Orsett archaeological plan].  Looked at as a data set, we have data from unknown number of subsets [structures], which may not be complete; this is unknown unknowns territory [6].

In terms of a jigsaw puzzle, the site is a bag of pieces, which come from an unknown number of jigsaws, which are probably not be complete, all without a Box.  Conventionally, the approach is to  find all the blue bits, and discard the rest; and while we have yet to distinguish between water and sky, post processional archaeology is making progress through an understanding of the significance of blueness. 

The problem arises because have allowed ourselves only a limited range of templates to interpret this data, we look for circles, [blue bits] largely ignoring the rest; a circle is a roundhouse, a simplistic hut; we can paint a picture; job done.
Thus, I inherited an archive of slightly soiled records, and an interim report that had identified three circular buildings, the defences and Romano-british kilns.  As the person responsible for preparing the final account of the site, I tried, but mostly failed to understand it;  the majority of the features had no real explanation and contribute nothing to the picture.  I might just be better at it now, but I have had 20 years to think about it, and time to develop theoretical structural archaeology.

The Story thus far.

What the report concludes about the history of the site was very roughly;

• Phase I - Middle Iron Age Polygonal building and Pottery
• Phase II - Late Iron Age Square Enclosure [Fort].
• Phase III - [Conquest Period] Multi-ditch Fort
• Phase IV - [Romano-British C 1^st ]  Occupation / Farm Buildings
• Phase V - [Romano-British C 2^nd] Occupation / Farm Buildings
• Phase VI - [Romano-British Late C 2^nd - C 4^th] Occupation / Farm Buildings? / Pottery Kilns
• Phase VII - [Early Saxon] Small Buildings [Grubenhauser]
• Phase VII –[Post-Saxon] Gravel extraction.

The Late Iron Age / Early Romano British phases II-III at Orsett

The conquest period [III] fort was short lived, with a palisade trench and a complex sequence of ditches, which probably resulted from a change of plan over the inclusion of the earlier square enclosure [II].   Most interestingly, these were rapidly backfilled, and in the southern corner there was with burnt material and a cache of Iron Age Spear heads.  All this could tell an interesting story; a local Trinovantian leader fortifying the strategic crossroads against the advancing Romans.  

Did they fight, or did they surrender and then slight their own defences?

Form and Forts 
Any detailed understanding of this part of the story, hits the same basic problem; leaving aside the three circular buildings, without identifying structures it is hard to contextualise the fort, or distinguish between built environments from before, during or after the fort.
All this is in stark contrast to our understanding of Roman forts, which are an exemplar, however,  the form of any fortification is governed by the same general considerations in this period.  In terms of a built environment I would expect the following buildings and structures to be present in some form;  

• Perimeter
• Fortified Gateway
• Watch towers
• H.Q. 
• Barracks  
• Forge 
• Granaries
• Cookhouse
• Stables

Clearly, at least the last four are common to large farm or high status dwelling, but at Orsett we had only 3 recognised buildings to work with; and if the main roundhouse [S9] is the H.Q., was it is a normal Roundhouse? Beyond this, understanding is mired in the complexity of unknowns in the built environments which may or may not have existed before and after the brief episode of the fort.
The Perimeter is the most important concept in a fortification, and following the basic principle that a chain is only a strong as its weakest link, its scale and construction method should be;

• Defendable with the manpower available;
• Credible to deal with expected threat.

By calculating various manpower models it was possible to estimate both the scale and the resources required to construct the fort. [below].  It was possible to estimate it would take at least 30 – 40 men a month to build the defences, which must be close to the minimum required to defend it, and excludes the gateway and acquisition of timber, and of course the construction of an unknown numbers of unknowns.  

An interpretive plan of the Orsett Fort entrance structure 

The entrance appeared to take the form of a heavy gate hidden behind a baffle to present direct assault, which leads to a narrow passage between rampart and a structure to the left of the gate.  [It was normal to reinforce or put towers to the left of gate to attack the unshielded right side of the attackers].  This entrance is scarcely four foot wide, very defensive, and quite unlike the Roman approach. 
The ditches themselves give material for the rampart, and present the attackers 18m of broken ground which make it harder for to keep in formation and discharge javelins [Pilum].  
To sum up; to understand the nature site before the construction of the defences is difficult without a clear boundary, and it is therefore hard to detect the nature and extent of any existing built environment, and distinguish its structures from those associated with the defences or subsequent occupation. Too many unknown unknowns.

An interpretive section and elevation of the Orsett Fort entrance structure.

Fighting till the end.

Not surprisingly, I see the site differently now, I had inherited a set of ideas that had their own momentum; some things I got wrong, mostly where I followed conventional wisdom and looked to other similar sites for parallels.  The problem is that Orsett, like all significant sites, is unique, so parallels not going to get you very far.  
There were roundish things, all three are unique, but a vague circularity is all that is required for a “roundhouse” which are proof of prehistoric “occupation”, which any amount of rubbish pits and postholes are not, without circles it’s just “activity”.  It is the circular logic of this tightening spiral of self-referential scholarship has impaired our understanding of built environments from this and other periods.

I am not sure that I had sufficient experience of this type of site, but you seldom do, as you cannot predict what you will find during excavation or post excavation, or more importantly, if you will ever work again on this type of project.   As Orsett illustrates, conventionally, archaeology is one of those enterprises where you sack everybody at the end of each job, which is no way to run anything that aspired to being a profession.  
However, sacking all the school staff at the end of the year would make education cheaper and prevent the formation of effective “education” lobbies and representation.  It works well for archaeology; thus, on many excavations a significant proportion of staff and workers will be beginners or inexperienced, but driven by low pay, no security or prospects of a career, most leave keeping costs and standards low.  It’s a chronic waste of endeavour and human resources, but archaeology is only important up until the point where the money gets involved.

Reverse engineering models of the Orsett rampart and ditches using spoil volume.

Orsett was the genesis of theoretical structural archaeology, driven my  own inability to progress with what was a tantalisingly significant piece of archaeology, [and more than just a fort].   There was clearly a need for a different set of templates, something more than roundhouses, not just for the Iron Age but also for Romano-British timber buildings outside of towns and villas, such as those associated with the Romano-British Pottery, whose product turned up on Hadrian's Wall. [7]
I consider that the difficulties of interpretation associated with super-complex archaeology like Orsett and numerous other sites is part of the reason academic archaeology went in the direction of post-processualism, with its emphasis on the study of what archaeologist don't find.  As a result, there has been little appreciation of the fundamental inadequacies of current thinking about built environments, or any systematic effort to address the problem. 
Thus, an evidence based approach to modelling and reverse engineering timber structures represented by TSA is destined to remain a post-university study for those who want to understand this aspect of the past.   

Sources and Further Reading
[1] G. A. Carter (1998): 'Excavations at the Orsett ‘Cock’ enclosure, Essex, 1976'. East Anglian Archaeology Report No 86. Illustrated by L.E. Collett
[2] Translated by W. A. McDevitte and W. S. Bohn
http://classics.mit.edu/Caesar/gallic.6.6.html [Accessed 13/04/11]

[3]http://en.wikipedia.org/wiki/Edward_the_Confessor#mediaviewer/File:Bayeux_Tapestry_scene1_EDWARD_REX.jpg

[4] http://en.wikipedia.org/wiki/St_James'_Park 

[5] Toller, H S 1980 `An interim report on the excavation of the Orsett 'Cock' enclosure, Essex: 1976-9' Britannia 11, 1980 35-42

[6] http://en.wikipedia.org/wiki/There_are_known_knowns  ; NB. the remark by United States Secretary of Defense Donald Rumsfeld gave to a question at a U.S. Department of Defense news briefing in February 2002.

[7] Paul Bidwell pers. com.