In my line of work as a commercial field archaeologist I have to be prepared to deal with various types of site in terms of date range and intended development but we also have multiple methods of determining what sort of archaeological survey to undertake on any given site. In the next few blog posts I’m going to run through each type of archaeological survey that we undertake, where it fits in the planning process and what it means for a development. And so, we will start at the beginning.
The Desk-Based Assessments (DBA) sometimes referred to as an Historic Environment Assessment (HEA) are generally the first step in the archaeological aspect of the planning process. They may not always be requested as, if an area is being heavily developed a previous DBA may have already covered the area of the site in question. For the most part a DBA is the beginning of the archaeological side of the planning process and if there is not already a HEA or DBA in place it will be the first thing that a town or county archaeological planning officer will request as part of the considerations on which archaeological conditions will be attached to planning permission.
This is relevant to any development whether a huge 200+ housing development, a golf course, or in some cases an extension (house extensions are heavily dependent on the area in which you live and not everything will always apply – covering the planning process is a whole different ball game). A Desk-Based Assessment is pretty much what it sounds like. We do a little research into the development area to see what type of previous activities are recorded.
One of the first places we go to is the Historical Environmental Record (HER) various aspects of which are available online via an approved gateway and in (some) local and/or regional libraries or county/town council offices or archives. The homepage is here searchable by region/town. And will give the interested individual all the information they need about who to contact and where the HER database can be accessed.
Within the HER itself we can find details of all previous archaeological excavations and assessments within a radius (usually 5km) of the intended development. This gives us a basis to work from as we can see which historical periods tend to dominate the area – for example some areas of Oxford are heavily Roman, whilst others have yielded very little Roman material but may have been used more during the Saxon period. So, we get a feel for the area.
Ordnance survey maps, also available through the HER and local libraries can show us the progression of activity on the site itself whether buildings were there, what the landscape was like, but these obviously only go back to the mid 19th century. Depending on the region we sometimes find that Tithe maps (taxation maps) are available and these, whilst not accurate in terms of scale, can indicate the function of a portion of land. Written records are important too and it may come as a surprise to know that we still consult the 1069 Domesday book for a lot of sites. This is an important document as it details explicitly the citizenry, functionality and wealth of a town or village often with other useful tidbits like this village was passed to this lord for services rendered to the king, or this land was gifted to the church for X reason. Another valuable source is the Victoria County History (VCH) available online here. It does not cover the whole country but gives the known historic background to various towns and cities. On occasion ancient texts may be employed, however these can be notoriously unreliable though the Romans did produce some useful itineraries such as the Peutinger Table which maps the road routes of the empire from India to Britain and survives as a medieval copy. Though these days we tend to consult Margary’s 1955 detailed study, mapping and projecting lines of the Roman roads of Britain, should we be trying to track one down, or see how close to one our site may be.
As part of the investigation we will also check the geological maps of the area. All available online as part of the British geological survey. The geology itself can sometimes give us an indication of what me might find – for instance raised gravel beds tend to have been preferred spots for prehistoric peoples of Mesolithic to Bronze Age date to pause or settle, so even if there is limited evidence in an area the geology itself may indicate a potential for archaeological remains based on what we understand of the habits of ancient peoples. Chalk will always show archaeological features clearly however remains such as bone are unlikely to survive. Clays and alluvial layers can be deep and may require careful examination as alluvial layering can hide early features below natural deposits. Also the nature of the landscape itself can be informative. Archaeological remains are more likely to survive intact in areas where there has been little development – though little development may also mean little to no chance of remains as the land was never used. We take all these things into account when creating our desk-based assessment.
So, a desk-based assessment – basically it is like a college research paper, detailing the likelihood of archaeological remains and their potential date(s) and importance to the area should they be found. It is this document that is used by the planning archaeologist within the county or borough to determine what (if anything) the next phase of archaeological process will be. Believe it or not there are a few cases where the desk-based assessment will be the only archaeological research done for a site. This occurs only if it is felt to be conclusive that there is little to no chance of archaeological remains being present in the area. Usually however it goes something like this:
Say our desk-based assessment discovered that the portion of land scheduled for development lay in an area within 5km of a Saxon settlement discovered through previous archaeological investigation. 2km from a second century small Roman villa/ farmstead (these can often be found in close proximity to others). Perhaps field walking in the 1960’s recovered two third century Roman coins and a prehistoric hand axe from the site itself, and the field lies just outside the known core of a village mentioned in Domesday as being of some substance and industry. This would warrant further archaeological investigation and depending on the landscape we would either move directly to archaeological trial trenching or potentially to a geophysical survey. Geophysical survey is now becoming much more common and I will cover it in the next blog post.
S. M. Porter
Professional archaeologist and author, S. M. Porter loves history, adventure and digging in the mud. Her career is in ruins - just where she wanted it to be.