George Loegering and relatives found a perfect circle of ice swirling in a stretch of the Sheyenne River, near Fargo.
“At first I thought, no way! It was surreal,” the 73-year-old retired engineer told The Associated Press about his Nov. 24 encounter. “You looked at it and you thought, how did it do that?”
He estimated that the frozen disk was about 55 feet in diameter and spinning at about one revolution every two minutes.
A video of the phenomenon he posted on YouTube went viral and has garnered comments from around the world.
U.S. National Weather Service meteorologists Allen Schlag of Bismark and Greg Gust in Grand Forks said a system of cold, dense air blanketing the region probably caused the disk to form in the river’s flow.
“It's not a continuous sheet of ice,” Schlag told the agency. “If you were to throw a grapefruit-sized rock on it, it would go through. It’s not a solid piece of ice — it’s a collection of ice cubes.”
Loegering said “growth rings” were clearly visible in the spinning mass.
The barometric pressure soared to a Fargo November record of 31.01 at about the time Loegering, his brother-in-law and nephew came across the phenomenon.
That would have created a very dense and stable atmosphere above the slowly freezing river, which the meteorologists say contributed to the circle’s formation.
Photo: George Loegering