Archaeology The Cairns Dig Diary 2017

The Cairns Day Eighteen 2017

An image taken from above the broch. With thanks to Rik Hammond

Thank you to the Cairns 2017 team and to director Martin in particular for inviting me up to spend some of the last week here on site!

My last visit was in 2013 and I can’t believe how much has changed – how much more archaeology has been exposed – and especially how wonderful the broch interior looks now that we are beginning to see its wonderfully preserved detail such as the furniture and floor surfaces.

Getting ready to sample the floors in the broch today
Getting ready to sample the floors in the broch

These floors are the main reason for my visit. I’m a geoarchaeologist, which means that I use a range of archaeological science techniques to investigate soils and sediments on site. I’ve come up to The Cairns to hopefully be able to help the team get the maximum possible information out of the vitally important floor deposits that we’re now seeing in various areas of the broch interior. These are easy to see in the images we now have of the broch – a patchwork of bright yellow, orange, black and brown surfaces made up of the detritus of a thousand everyday activities.

I’m using a technique called soil micromorphology to enable us to see this level of detail in a way we can’t using traditional excavation methods. Small blocks of the floor material are carefully removed, using a metal tin in order to avoid disturbance of the deposits. Resin is poured into these blocks and hardened, allowing a microscope slide to be made through the ‘thin section slice’ of the floor deposits.

Jo sampling the broch floor deposits
Jo sampling the broch floor deposits

Under the microscope, we can examine in detail what often proves to be a sequence of many, many more deposits that can be seen with the naked eye. It goes without saying that micromorphology is a powerful tool for understanding how these deposits form and the microscopic information they contain – fuel residues, bone, botanics and other pointers to human activity, as well as a whole range of indicators for environmental conditions on site and how these have changed through time.

With the weather on side, we made a great start today – examining the floors, making a start on sampling, and most important of all, talking strategy for next season. With more and more of this wonderfully preserved detail being exposed every day, there’s no doubt that the floor surfaces at the Cairns are going to be a focus for attention for a long time to come!

Jo McKenzie, Honorary Research Fellow, University of Bradford


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