Stories of Lake Coring in Assynt and Coigach

Posted by on Nov 27, 2019 in Excavation | No Comments
Stories of Lake Coring in Assynt and Coigach

We’re delighted to share a guest post from Lou, a PhD student who has been carrying out research in Assynt. Her work will contribute to our understanding of the past environment at Clachtoll, helping us to build up a clearer picture of the landscape through the millennia.

I’m Lou and I’m a student at Newcastle University. My PhD is a collaborative project between the University and AOC Archaeology. You can find out exactly what it will involve on the AOC website (link to web blurb). In May I went to Assynt to take some sediment cores from lochs associated with Clachtoll broch and other Iron Age sites in the area. This is what we got up to.

This tricky thing about fieldwork is that until you’ve done it a lot, it will always take longer than you think it will, and the best laid schemes will Gang aft agley

The plan was simple:

Day 1 – Kit over to Clachtoll, take sediment depths, retrieve core if all going well.

Day 2 – finish coring and pack up kit for next site

Day 3 – Go to second coring site, unpack kit, take sediment depths,

Day 4 – Core second site

Day 5 – Visit (and possibly core) third site

Easy right? Wrong! Day one went great until lunchtime – we were able to park our van much closer to site than planned, which meant we had the boats and coring platform on the water by mid-morning, but counter to what might be expected, the thickest sediment wasn’t under the water, but actually in the bog to the south.

Assembling the coring platform at Clachtoll. Can you spot the deliberate mistake?
A gauge core used to determine the depth and type of sediment. This shows gyttja to the left, and a pinky-brown clay to the right

This required a bit of rapid improvisation, as the kit required for coring boggy ground (as opposed to lake) was 370 miles away in Newcastle.  Happily we were able to arrange the ‘Russian corer’ to be couriered to Graeme who was joining us on Tuesday, so all was not lost. In the meantime, we decided to scope out some alternative sites. A fortuitous meeting with Bob Cook from Assynt Crofters Trust established that they would be happy for us to look at the next nearest water body – Loch an Aigeil.

Sunshine on Loch an Aigeil. The brown pipe I’m sitting over is used to hold a column of loch sediment.

Day 2: All hands to the deck!

The sediment in Loch an Aigeil proved to be a few meters deep, and comprised mainly of gyttja – organic lake mud – ideal for coring.

You might be wondering why there are no pictures of the coring itself – this is because the 2.7m of material requires not only a farm jack to remove it from the water, but everyone that can be safely fitted in the boat to manoeuvre it on board and get it sealed: it is seriously heavy and very unwieldy!

Day 3

With one sediment core done it was time to have another think. Thanks to some discussions with Dave McBain of Historic Assynt, I had some alternative sites to look at while we awaited the kit to arrive with Graeme. So Monday and Tuesday saw us visiting the northern-most crannog at Loch Awe and crannog at Loch Borralan. Unfortunately, neither site turned out have the types of sediment needed for my project.

Day 4: Back to Clachtoll

Our final day took us back to Clachtoll, where it was quite short (if a little wet!) work to retrieve a sediment core from the marshy area next to the loch.

Russian coring at Clachtoll
Photo 5: The contents of Russian Core being labelled and packed