On a cold Saturday in November 2013, retired engineer George Loegering was out hunting with relatives along the Sheyenne River in North Dakota when he spotted something that looked like a record turning on a turntable. A near-perfect disc of ice, about 55 feet (17 m) across, was slowly rotating in the open water.
George Loegering’s Sheyenne River sighting
Loegering saw the disc on 23 November 2013 and recorded it on video and in photographs. News of the “spinning ice circle” spread quickly that Thanksgiving week, from Live Science and Fox News to the Daily Mail.
He could not say how long it had been turning, but he thought it must have been a long time. As evidence he pointed to the rings visible across the disc, like growth rings marking its slow build-up. By the following Tuesday the circle had stopped spinning and frozen in place, though its round outline was still clear on the river.
How river ice circles form
National Weather Service forecasters told the Associated Press that cold, dense air had frozen the river surface in pieces. Floating chunks of ice were then caught in an eddy, a slowly rotating current, and began to circle together.
Ice circles, also called ice discs or ice pancakes, are thought to form where a river’s current creates rotational shear, often on the outside of a bend. That twisting flow breaks off a section of ice and spins it. As the slab turns, it grinds against the surrounding ice and its edges wear smooth, which is why the finished disc looks so neatly round.
Research has added more pieces to the puzzle. A 2016 study by Dorbolo and colleagues found that a disc can keep rotating because meltwater flows away from the melting ice. Discs can even spin in still water: the ice chills the water beside it, the colder, denser water sinks, and the circular current that results turns the disc.
Where ice discs appear
Ice circles are rare, but they turn up on slow-moving rivers and lakes in cold climates, most often in Scandinavia and North America, with sightings also in England, Wales and Germany. Sizes vary enormously: discs more than 15 m (49 ft) across have been recorded, and one at Vana-Vigala in Estonia was reported to exceed 20 m.
The most famous recent example came in January 2019, when a disc about 91 m (nearly 300 ft) wide spun on the Presumpscot River in Westbrook, Maine. Smaller ice swirls on Boston’s Charles River were studied by MIT researchers in 1993, who also linked them to current-driven eddies.
Watching river ice safely
Enjoy an ice circle from the bank. River ice forming around moving water is thin and uneven, and a disc is a loose, floating slab, so photograph it with a zoom lens and stay on solid ground.
For more strange ice, see lake ice driven onto a shoreline and the rounded ice pieces near Lake Michigan.
Related reading
- lake ice driven onto a shoreline
- rounded ice pieces near Lake Michigan
- Snow Roller: A Strange Meteorological Phenomenon
- Spectacular Photos of Bubbles Frozen in Frigid Temperatures
- Abraham Lake’s Ice Bubbles: Layers beneath the Surface
- Frozen Bubbles at Mount Washington Observatory
- Yellowknife’s Hot-Water Cloud in Extreme Cold
- Río Celeste: The Science of Its Blue Water and a Forest Walk
- Hamilton Pool Preserve: Geology, Habitat and Planning a Visit
Sources
Credited photographs: George Loegering.
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