Saturday, 17 June 2017

Environmental Coring

Today's weather wasn't ideal for members of the Ardnamurchan History & Heritage Association to spend a day at Swordle, at the invitation of Archaeology Scotland, to learn about environmental coring.

The site chosen was just to the east of the Viking boat burial, now marked with stones - see the Ardnamurchan Transition Project's website here - in a....

....tussocky field, where Becca Barclay and Phil Richardson of Archaeology Scotland showed us how a Dutch gouge, a type of auger, is assembled and then pushed down into the underlying peat.

When pulled up, the last metre or so contains a sample of the peat which can then be....

....analysed for content. This is a sample from the upper section which is largely well-preserved vegetation very similar to what is growing today.

Becca, who has experience of this sort of work from time spent in Iceland, showed us how to classify sections of the sample according to their contents, using the Troels-Smith system used for organic-rich sediments.

Once below about a metre, the sediment became darker and contained increasing amounts of woody material, suggesting that the area had been wooded some time in the past. The exact date can only be found by studying the pollen, but an exceedingly rough rule-of-thumb for western Scotland is that a foot of peat collects in about a hundred yards - so this wood might be four hundred years old.

Bark on the woody material suggested it might have been birch, but the highlight of the day was finding pieces of an almost perfectly preserved hazelnut shell at a depth of 1.58m - so it might have been about 500 years old. The auger hit bedrock at just over 2m depth.

Many thanks indeed to Becca and Phil for an informative, enjoyable, if damp expedition.

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