Mysterious disappearance of Scottish loch’s water exposes parts of ancient settlement not seen since 1300s

Water levels in a freshwater Scottish loch mysteriously reached a 750-year low earlier this year, according to archaeologists studying the remains of an ancient settlement on a man-made island.

Researchers at Loch Vaa in the Cairngorms collected and carbon-dated timbers which had been covered by water since the 13th Century, to reveal that water levels reached a historic low in May 2019.

However, what remains unclear is what caused the loch to drain. It is a spring-fed loch, with no other major water inlet or outlets, but in May the water levels had fallen by 1.4 metres. It was like someone had “pulled a plug”, according to locals, and took until July for the loch to regain its usual level.

The archaeological team assessed the impact of the millions of missing litres of water on the loch’s “crannog” – an ancient man-made island common in lochs across Scotland, and revealed the record water level low.

They were able to pull up pieces of wood which had been submerged and protected by the waters since the 13th Century.

Dr Michael Stratigos of the Scottish Universities Environmental Research Centre, who is working on a project investigating iron age crannogs in Loch Tay in the northern Cairngorms, told The Independent the low water levels presented a rare opportunity to see more of the crannog at Loch Vaa.

“It’s a site I’d had on my radar as something of interest during my PhD a few years back, but never got around to investigating it.

“So when I heard that the water levels had dropped, it was a good chance to investigate it – not only because it makes the archaeological material more accessible, but also [because it allowed them] to assess whether the archaeological deposits had been negatively affected.

“So I got in touch with the landowners and the local authorities to go to have a look.”

The work included taking a sample of one of the timbers used at the crannog for radiocarbon dating.

“It seems as though the water levels had dropped to that position before,” Dr Stratigos said, and explained this was indicated by a complete absence of organic matter surviving at the level the timber was retrieved from.

“The radiocarbon dating we took came from a timber that was just about 15cm below where the water level was in May. So what that says to me is that sometime in the last 750 years the level had dropped to maybe as low as that point before, but no lower.”

“It could have happened very shortly after that timber went into use on the crannog. It might have happened much more recently, it’s impossible to say.”

But he said such low levels of water would have been extremely rare, otherwise the wood they tested simply wouldn’t have survived.

“It’s notable that the timber we sampled was birch, because birch isn’t particularly robust – it doesn’t hold-up well,” he said. “If water levels had even got close to where they were in May, you would lose birch in that upper portion through wave action and the freezing and thawing of the water’s surface.”

“Where it was in May, it’s not been significantly lower than that in the last 750 years.”

But Dr Stratigos said exploring the reasons why the loch had lost so much water so quickly was “far beyond the remit of archaeology”.

Locals have previously blamed Scottish Water, suggesting boreholes have drained the aquifers supplying the loch, but this has been rejected by the company, which said their activities 3 miles upstream were too far away to affect it.

The Scottish Environment Protection Agency has suggested the loch had suffered due to a “relatively dry” winter, the BBC reports.

This came after a major summer heatwave last year during which caused widespread drought, hosepipe bans, crop failures, and a number of wildfires.

The prospect of similar heatwaves, which are becoming increasingly likely due to climate change has concerned archaeologists.

This month, public body Historic Environment Scotland, published a stark warning of how a changing climate could impact Scotland’s heritage.

Their report said: “Many changes to our climate are already happening and further changes are unavoidable. If we are to reduce their impact, adaptation is essential. For the historic environment in Scotland, this means addressing the physical impact of increased rainfall, more frequent extreme weather events, increasing temperatures, rising seas and shifting coasts. These changes, individually and collectively, are already having a damaging impact on our historic environment.”

Dr Stratigos added: “Wetland archaeology, crannogs being prominent in Scotland among them, are very sensitive to climate change. As these types of extreme events become more common we are likely to see cultural heritage put at risk.”