To mark Friday the 13th, in a leap year, just after a full moon, this blog post is going to talk about some of the weirder things that have happened on Loch Tay. Building and living on a crannog is a peculiar thing to do in itself, and being out on the water gives you a unique perspective and experience. But things may have gotten even weirder when difficult-to-explain events occurred.

A calm evening on Loch Tay

Perhaps surprisingly, a first-hand account of a tsunami comes from Loch Tay in 1784 recorded in the Old Statistical Account of Scotland. On Sunday the 12th of September, the water in Kenmore Bay at the east end of the loch was seen heaving up and down, before withdrawing out about 100 yards from the normal shoreline. At this point the water began to rush back in towards the shore in a wave about 5 feet higher than where the normal shoreline was. Successive waves separated by 7 minutes, but less intense than the first, kept appearing for the rest of the day. These waves then happened again each day for the next four days, and intermittently after that until mid-October of that year. These ‘agitations’, as they are referred to in the Old Statistical Account, were very puzzling to the author of the account. He notes that the weather was fine, and there was nothing else unusual going on. So what may have caused this?

It is not known precisely, but a good bet would be small (even imperceptible) earthquakes and landslips. Loch Tay sits in an active geological fault, and there is evidence in the loch for landslips in the past where parts of the hillsides around the loch fell into the water. Trees dating from the Neolithic through to the mid-first millennium AD have been found submerged in the loch near the north shore at Craggantoul. Given their superimposition and range of dates, land slips from the hillside above seem the most likely explanation (as opposed to lower loch levels in the past). These kinds of earthquakes and landslips can result in some of the tallest tsunami waves on record. However, since 1784, no tsunamis in the loch have been recorded.

Very difficult to imagine a tsunami rolling down the loch from the east on Loch Tay, but it happened!

Another weird occurrence, is an event which took place in 2005. Following the largest recorded earthquake for 15 years in Killin (a 2.5 on the Richter Scale), local residents reported seeing, during the night, a green glowing globe in the sky rising slowly out and above the loch. It turns out, that this probably was methane gas. The gas was created by microbes at the bottom of the loch eating organic material, but trapped in the loch-bottom sediment where it built up. When agitated by the earthquake, the gas then escaped in a large burst. Research of the loch bottom found that the 2005 event was probably not a one off, rather, that these gas escapes have occurred with some frequency since the loch has been ice-free following the last Ice Age.

It is very difficult to know if Iron Age crannog dwellers experienced earthquakes, tsunamis or green glowing gas on the loch. But it seems there is at least some chance that they did. How these might have impacted their life on water is of course more difficult to ascertain, yet it is worth keeping in mind that weird things did occur in the past. People certainly would have explained these, and other natural events too, in their own way. In what terms or context is probably unknowable, but past peoples’ responses to such events may be detectable in the archaeological record. Better chronological precision of the archaeological is an essential first step in attempting to do that.

So on this Friday the 13th, remember that life in the past could get very weird, and that the Iron Age crannog dwellers of Loch Tay may one morning have had to clean up after a tsunami, or perhaps were staring up at a green-glowing blob over the water on night.