A man hiking in Scotland was surprised to spot a huge, perfectly round disc of ice slowly rotating in a pool at the base of a waterfall. Dan Brown, of Dunoon, was carrying his mountain bike up the Beinn Bhuidhe munro when he noticed the strange ice formation and stopped to record a video.
"We’d taken mountain bikes with us and, for the best part, had been carrying them up a hydro track,” Brown told the South West News Service. “Visibility wasn’t great but after about an hour and a half, the snow stopped and cloud cover started to clear.”
Brown's video, which you can watch below, shows the disc from various angles. “Neither of us had ever seen anything like it – a perfect circle of ice slowly rotating in the water,” said Brown.
Unlike dangerous, slushy frazil ice, which occurs when fast-moving water freezes into small, irregular crystals, an ice disc or ice circle is formed when water is slowly moving in a vortex.
As Smithsonian Magazine explains, the rotating disc is created when one side of a body of water is moving faster than the other. They can be created by ice that forms while the water is moving, or when a chunk of a large ice sheet breaks away and drifts into a suitable area.
Most discs are fairly small, like this one, but they can grow to hundreds of feet in diameter. In January 2019, a 300ft ice disc made headlines in Maine, where it was spotted in the Presumpscot River in Westbrook.
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Cat is the editor of Advnture, She’s been a journalist for 15 years, and was fitness and wellbeing editor on TechRadar before joining the Advnture team in 2022. She’s a UK Athletics qualified run leader, and in her spare time enjoys nothing more than lacing up her shoes and hitting the roads and trails (the muddier, the better), usually wearing at least two sports watches.