Birrens: putting a Roman fort in context

We had a great week of survey at Birrens Roman Fort, near Middlebie, earlier in the

Tom and Ron carrying out resistivity survey

month. Overall, volunteers, together with University of Glasgow students and staff walked nearly 35km, collecting some fascinating data that has really helped to put the Roman fort into context.

We had a number of visits from the local media. Giles Carey and Dr. Richard Jones explain here a bit of background to the fort and what the survey hoped to achieve.


Courtesy DNG Media

And the results were definitely worth braving the weather for. Dr. Richard Jones, who led the work, is excited by the results. He said:

The results of this survey at Birrens are exciting because they seem to show a fort lying next to, and probably earlier than, the known (excavated)  fort.  As well as the defences, there is a lot of  detail within this new fort which we want to understand.

Whilst the results will undergo further analysis and interpretation, a number of features are already apparent.

To the west of the fort
A large scale magnetic survey was conducted to the West of the earthworks of the fort, where a series of ramparts and the line of the Roman road are visible on aerial photographs. This field is currently under pasture, and gives little indication of what lies beneath.

Magnetic survey gets underway – little survives above ground

However, the results are quite staggering. Below is a greyscale view of the results. The readings taken as the equipment is walked across the ground surface are all plotted together, and have been placed on a map to reveal a buried ‘plan’ of archaeological deposits. Areas of positive magnetic response are shown as black; areas of negative magnetic response are shown as white. These results show a series of features which correspond well with the aerial photographs of the site.

Initial results of magnetic survey to West of fort.

A series of buildings are visible, aligned along north-south and east-west streets, within a fort with considerable ramparts to the North and West. A number of other features can be suggested – a line of circular anomalies close to the intersection of the roads could be a series of ovens. What is clear is that there was a sequence of rebuilding here, and what survives today is only a small part of a much more extensive military landscape in use over at least 100 years.

Initial interpretation: yellow: road, purple: defences; green: weak features to the west of the fort/annexe; light blue: narrow positive magnetic anomaly running from the fort interior approximately westward into the annexe.

Volunteers also carried out some resistivity survey in this western annexe – and the roads are immediately obvious in this data.

To the north of the fort
A resistivity survey was carried out to the north of the surviving fort earthworks, covering 22 grids in an area which aerial photographs suggested the via principia  (the main road) of the fort might run through.

The results are a bit harder to interpret, but there are certainly features here which are suggestive of large ditches. It is likely that we will be returning to carry out some more magnetic survey in this area – it might help us clear up exactly what is going in this northern area.

The resistivity survey detects changes in the moisture level of the soil related to archaeological deposits below the ground. The greyscale below shows initial interpretation – the white areas indicate areas of low resistance. Here electrical current passes through the soil more easily, indicating that buried deposits are damper – such as might be found in a ditch. The black areas indicate high resistance. These might indicate buried stonework – electrical current cannot pass so easily through the soil around a wall for instance, because it is drier.

Initial interpretation of resistivity survey. Yellow: drains; red: low resistivity anomalies some of which may represent ditches; blue: higher resistivity anomalies of uncertain identity.

Overall, this data has really helped to show that there’s more to Roman activity in this area than meets the eye. A lot is buried below ground, that we just can’t see any more above the surface. The results of the geophysical survey are very important therefore in finding out more about this complex military landscape.

A huge thank you to all our volunteers – who braved some challenging weather and sheep! We would also like to say thanks to the 50 or so people who turned up to see the results on the Open Day – it was a very enjoyable day.  

The small display receives its first Open Day visitor

We would also like to thank Middlebie Parish History Group for their support, particularly Janet Foreman and Ian Aitken-Kemp, and to our project funders as well as to the Mouswald Trust and the Dumfries & Galloway Natural History and Antiquarian Society and the landowner, Mr Denis Martindale.

A tired but happy team

Would you like to be part of the volunteer team next time? Please contact us to find out about upcoming surveys.

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Welcome on Day of Archaeology 2012

Together with over 700 archaeologists across the world, we are telling the world about Discovering Dumfries and Galloway’s Past on the Day of Archaeology website. It’s a great opportunity to find out more about what archaeologists get up to on a ‘typical’ day – see the website and you can read our post here.

In honour of the day, let me tell you about more about Discovering Dumfries and Galloway’s Past, and how you can get involved.

Discovering Dumfries and Galloway’s Past is an exciting new community archaeology project based in south-west Scotland, 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:

Glasgow University Archaeologists undertaking resistivity 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.

Glasgow University Archaeologists undertaking magnetic survey

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.

Seeing beneath the soil: the results of magnetic survey at the Roman Fort at Bankhead, Dalswinton

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!

You can find out more about our work at Birrens in a previous post. We are also hoping to post the results up very shortly – so watch this space!

That’s all for now – we look forward to seeing you at Birrens next Saturday, but you can always contact us if you have any questions or comments at all!

Birrens Roman Fort, Middlebie

Seeing beneath the soil: the results of magnetic survey at the Roman Fort at Dalswinton

Our first survey project is happening at Birrens Roman Fort, near Middlebie , Annandale, described as

“a site with a unique role in Romano-British frontier history”.

We have places available on the resistance survey for volunteers on Tuesday-Thursday 3rd-5th of July. If you would like to put your name down for one or more days, please contact Giles – giles.carey@glasgow.ac.uk or 01387 702056. Find out more about what will be involved on our Frequently Asked Questions page.

We will also be running an Open Day between 10 and 4 on Saturday 7th July. Meet at Middlebie Community Hall – there will be a small display about the site, and the chance to see archaeology in action – with guided walks to see the current surveys in progress. Hopefully, there will also be a sneak preview of the current results!

Download a poster with all the details (PDF).

Why not find out more about the fort on Canmore? http://canmore.rcahms.gov.uk/en/site/67099/details/birrens/ 
Interesting fact – its Roman name – Blatobulgium – literally means “flour sack” (presumably because it had 3 granaries instead of the usual 2).

As ever, any queries or questions – just drop us a line!

Hello and welcome

Welcome to our new blog. Here, you can keep up to date with all that’s happening as part of Discovering Dumfries and Galloway’s Past – an exciting new community archaeology project which offers you an opportunity to be involved in surveying and interpreting the region’s fascinating archaeology.

Over the next few months, we will be posting about up and coming geophysical survey projects in the region – and offering you chances to get involved in these surveys.

We will also be posting the results of the surveys here so you can see what volunteers have been up to as the project progresses.

Please get in touch if you have any questions at all – you can find all our contact details here as well as some frequently asked questions.