Yarrows Heritage Trust

Community Excavation of Thrumster Broch, Caithness

Friday 22nd of July

We are assisting the Yarrows Heritage Trust in their excavation of a broch in Caithness. AOC’s John Barber is directing excavations, and myself and Alan Duffy are also on hand this week.

Thrumster Broch lies on Thrumster Estate. It was modified to form an ‘oval garden’ in around 1810 according to estate records. Subsequently its wall was slighted on the south side and a summer house was built in the entrance area of the monument. The broch was previously believed to be solid-walled, but our excavations quickly revealed intra-mural galleries. We have also discovered a previously unknown entranceway that we believe was filled in along with some of the galleries in the north-western area of the broch, in an attempt to stabilise the building when subsidence of the ground began to cause structural problems. We now believe that the entranceway recorded in the area in which the summer house was built was a secondary entrance, replacing the recently discovered entrance.

We arrive on site to start work each day at 9 am. I give volunteers a site induction on their first day on site; after this, they can get stuck in as soon as they arrive each day. Our community projects are very relaxed – people can turn up as and when they like for as long as they like. This means that people can get involved in our projects by fitting their participation around their daily lives. What’s more, participation is completely FREE, which is always a winner.

We have 15 people digging with us today, all of whom have been on site previously. Some of our volunteers are studying archaeology or have done so in the past, but almost three quarters of the project’s participants had never dug an archaeological site before – and here they are digging a two thousand year old monument! Our volunteers range in age from four year olds to 74 year olds, and each person makes a worthwhile contribution to the project.

As we are nearing the end of the project, we are not opening any new trenches but are focussing on those already opened. We are trying not to create any more quandaries, but hope desperately to resolve those we are already investigating! For example, the broch wall has up to five or six construction stages depending on its complexity in the area examined. Where galleries exist, two or three inner wall elements and three outer have been noted. We want to know if all of these structural elements are contemporaneous (built at the same time) or whether they have been added over time, enlarging an original structure.

I help get the volunteers started for the day, making sure everyone has the right tools and knows what they are doing. Some volunteers are trowelling; others are drawing plans or sections; beginning to backfill; using the dumpy level and taking soil samples.  While digging, volunteers have a plastic tray to hand, into which they place all bulk finds (animal bone, small pieces of pottery, modern finds). Small finds (large pieces of pottery or rim sherds, worked bone, worked stone objects and so on) are bagged up straight away, their details recorded in the register and their exact locations plotted.

Local volunteer Meg with a large Iron Age rim sherd from Trench 4

I have been surveying the site using a total station, an electronic device that records the exact location in three dimensions of any given point. It is used to map and create 3D plans of a site, and to record the location of finds and so on. On a stone-built site like a broch, this means recording the location of a lot of stones! Site photographs are overlaid with the data gathered with the total station to create 3D maps.

AOC's Gemma explains how the total station works to Jonie

We stop for a tea break at about 10.30am and then everyone cracks on. I ask Jonie to help me take some levels using the dumpy level; although we have a total station, we teach the volunteers to use the dumpy level as many archaeological societies use them regularly, and we want to teach people new skills that they will use again and again.

We have decided to bury a time capsule at the end of excavations; at lunchtime, everyone shows what they have brought. Items include a CD of photographs from our excavations; the results from the weekend’s county show from the local paper; a key ring from the Caithness Broch Centre, and some coins. The volunteers sign the plastic tub and we seal it in plastic bags, taped shut. This way their contribution to the project becomes part of the time capsule itself. It will be buried on the final day.

Work continues through the afternoon, with another tea break prompting discussions of cannibalism: how hungry would you have to be before you started eating your comrades? Looking at our motley and dusty crew, I guess pretty desperate.  At about 4.30pm we pack up our tools for the day, and the volunteers sort and bag up their bulk finds. We then have a site tour, led by John. The team walks around the site in the sunshine, discussing the day’s findings and tomorrows challenges. By 5.30pm everyone heads home to rest their weary limbs for another day.

Some of the team on the penultimate day of excavations

Post script

Backfilling was completed on Saturday 23rd of July. Over 45 people were involved in the project during the three week season of excavation, volunteering over 1000 man hours in total. The project relied wholly on the enthusiasm and commitment of each and every one of these volunteers, and for this AOC and Yarrows Heritage Trust would like to express their gratitude.