By Alan S and Sandy Gerrard
In the first part of this series, we briefly examined the pre-excavation activities of a typical archaeology project. We now continue our overview of the different types of archaeological practice, and their predilection to cause damage to the archaeological record, by examining various aspects of excavation technique.
But first, what do we actually mean by the term ‘damage’? The archaeological resource is a limited and dwindling asset. Excavation is always destructive and it is therefore crucial that it is carried out as carefully and efficiently as possible. Any deposits removed during the course of an excavation are destroyed together with the information they held. It is therefore the duty of the archaeologist to ensure that as much accurate information as possible is collected. If an excavation is not recorded correctly, any information from that excavation is lost forever. Therefore it is of prime importance that accurate records are kept of what has been excavated, and where. That includes any and all finds, features and samples, from all contexts. If records are not kept, knowledge is lost, and the damage to the archaeological record is total.
This is where the most damage is done! Let’s start by saying yes, all excavation is damaging. However the difference between a good excavation and a bad excavation is simple. A good excavation enhances our knowledge and appreciation of the past whilst a bad one adds nothing or at best very little and at worst may provide fallacious results which might seriously impair and even distort our understanding.
‘Excavation’ undertaken by metal detectorists can be without doubt one of the most damaging activities. Although there may have been some desk-based research prior to hitting the site, there will rarely be a formal methodology to the excavation other than ‘ping’/dig! Some detectorists may advise the Portable Antiquities Scheme (PAS) of any significant (read metallic) finds but often the valuable context of the finds will have been trashed together with associated items (pottery, flints, fibres, animal bone etc) which are often discarded as irrelevant by the detectorist. Recording may comprise at best of a photo (or video) or two of the finds, and a GPS reference which may point to no more than a particular field, or parish. The loss of knowledge in these situations will be immense and of course in the long run means that many of the questions of future generations will go unanswered as a result.
An Open Area Excavation can be the most informative and destructive in equal measures. The technique involves stripping away all of the layers in reverse to how they were formed. So off comes the turf and topsoil first and then each layer, feature and structure until nothing but subsoil or bedrock remains. Carried out properly by competent archaeologists this technique can provide more information than any other but the price can be the total destruction of the site being examined. Sometimes structures encountered are left in place but sometimes these too are removed in order to look for information below them.
Test pitting, Sampling and Trenching techniques are used by many projects as a way of mitigating the limits of any damage. Using these methods, the extent of excavation is reduced to the bare minimum needed to meet the project’s objectives. Test pits are usually 1m square excavations, whilst trenches can be any length or width and dependent upon the documented project objectives, both may be taken down as far as the ‘natural’ or bedrock level, in separate layers or ‘contexts’ to ensure nothing is missed. Section drawings and photographs are taken of the stratigraphy and any features uncovered. With larger excavations, and particularly in Rescue Archaeology situations, test pits may be extended, or repeated across an area to provide an agreed sampled percentage coverage of the site. In all cases, careful recording of each context is undertaken, and where necessary soil samples may be taken for laboratory analysis of pollen grains, snail shells, bone and insect remains etc. before the pit is backfilled at the end of the excavation. This strategy of course has the huge advantage of allowing some or even most of the archaeology to survive for future ‘better informed’ excavations in the future, but the limited nature of the work means that the results themselves will be incomplete and therefore possibly misleading.
Next time, we’ll finish off by looking at the post excavation activities.