Here at Living on Water we have been patiently waiting to get stuck into our lab work, and today is the day!
So far, our samples have been taken from structural timber elements of the crannogs we examined last summer – Oakbank, Dall Bay South and Milton Morenish. Our samples were then delivered to our dendrochronologist (Dr Anne Crone of AOC Archaeology), and we now have our first floating tree-ring chronologies (thanks Anne!). These are from just the oak samples that we collected in 2017, and we now have the samples themselves so we are ready to begin running our first our first wiggle-match dates.
The floating chronologies are groups of timbers Anne was able to place in a relative sequence (ie. these three trees were felled two years before that tree and seven years before those five trees). In classic dendrochronology you would normally be able to track this back, ring by ring, from today to whenever your sample dates using a master chronology normally composed of measurements from many individual trees. However, in Scotland we are not so lucky, with a master chronology that only extends back about 500-1000 years. So this is where radiocarbon wiggle-matching comes in. We can provide a calendar date with radiocarbon (with some degree of error) to the chronologies identified in our crannog timbers.
Our first job was to decide which floating chronologies focus on. We have selected our first couple of samples to wiggle-match, but we’ll be focusing on the best match we have so far which is from Milton Morenish. All of the oak timbers from Trench 1 here have been identified as being felled in the same year (in late winter/early spring). We will now take the longest lived of this group, which has 65 rings (pictured below) and sub-sample it for radiocarbon dating. You can read more about how radiocarbon dating works here http://www.livingonwater.scot/14c/ and we’ll be explaining more about how wiggle-matching specifically is undertaken in these blog posts.
Over the next few weeks, we’ll keep you updated with how our work progresses, some finer points on how the science of all this works, and ultimately, some insight into the people who built and lived on crannogs in Loch Tay 2500 years ago in the Early Iron Age.