Well, hello from a soggy south-west Scotland. I’m Giles, Development Officer for Discovering Dumfries and Galloway’s Past and I wanted to tell you on Day of Archaeology 2012 about the project and what we are going to be doing over the next week or so…
DDGP is an exciting new community archaeology project based in south-west, providing training in using geophysical survey to help volunteers record, understand and interpret the region’s fascinating archaeology. There’s going to be plenty of opportunity for local people right across the region to get involved in the surveys – it’s a great way to find out more about buried archaeology without having to excavate.
What is geophysics, and what can we find out using it?
Not all archaeology is about excavation – you may have come across ‘geofizz’ on TV’s Time Team where it’s often used to plan where to put the trenches in. Geophysics is a way of mapping buried archaeological deposits – be they ditches, pits or building material – without ever breaking the ground surface.
There are two main techniques for geophysical survey:
Resistivity: By passing a small electrical current into the ground, and measuring the amount of resistance that results, it is possible to locate buried remains of archaeological interest.
Resistance is related to the amount of moisture in the soil. Around buried walls, for example, the surrounding soil will often be dryer. The current cannot pass so easily through this dry soil, so stonework can often show up as areas of higher resistance. This technique is therefore ideal for locating building walls and foundations.
Magnetometry: This technique detects extremely small variations in the earth’s magnetic field, caused when the ground has been disturbed by previous activity. Burning, for instance, will often leave a significant magnetic trace.
Magnetometry is excellent for locating ditches, pits, middens, hearths and kilns – and is great at covering large areas quite quickly.
The great thing about geophysical survey is that the results can be rapidly downloaded on site to a laptop, and even with minimum processing it is possible to define ‘anomalies’ which can represent buried archaeology. For volunteers on the project surveys this is great – they can see the fruits of their labours in the field. We are aiming to get these very quickly into reports which will be uploaded onto our website, to share them with as wide an audience as possible.
Our next survey
It’s all a bit hectic in the office today as we put the finishing touches to our programme for next week’s survey. We’ll be undertaken both magnetic and resistivity survey at the nationally important site of the Roman fort at Birrens. This continues work that the University of Glasgow have been concentrating on – looking in and around Roman military sites in Eastern Dumfriesshire.
This has looked at fabulous sites around Lockerbie, such as the Roman fort at Dalswinton. As you can see this has added loads of detail (as you can see on the right) to both the inside of the fort of Bankhead and the surrounding area – which aerial photographs have shown to be really interesting.
At Birrens Roman fort, near Middlebie, we’ll be focusing on similar things. A group of 6 volunteers will be joining us for 3 days next week to carry out some resistivity survey on the interior – hopefully we’ll get detail of the street pattern, as well as an idea of how the buildings – both the barrack blocks and administrative headquarters of the fort – were laid out.
You can find out more about Birrens fort – known to the Romans as blatobulgium (literally the ‘flour sack’) here.
We’re having an Open Day on Saturday July 7th – it’ll be a great chance to show the public the results as well as an opportunity to show just how geophysics ‘works’ – including the amount of walking in straight lines that’s involved! The response has been fantastic locally – so here’s hoping for some sunshine!
I hope this has wet your apetite both for ‘geophysics’ and the project – please see our website to keep up to date with the latest – discoveringdgpast.wordpress.com.
The project is jointly funded by the Scottish Government and The European Community, Dumfries and Galloway Leader 2007-2013; The Crichton Foundation and The University of Glasgow.