Nature can often present us with some rather wonderful and rare sights. Sights such as spinning ice circles in slow-moving rivers. One particularly giant and impressive example popped up in the Presumpscot River in Westbrook, Maine recently.
Ice circles are an unusual occurrence forming on the outer bends in rivers where water creates a force called “rotational shear”. A chunk or chunks of the ice and then twists around. As the chunk of ice starts to spin with the current of the water, it grinds along its edge, ultimately smoothing itself into a near perfect circle. In this case, that ice circle had a diameter of almost 90 metres (300ft).
Looking at the size of it in the videos, it absolutely dwarfs the buildings that flank it on either side of the river, and it’s a very impressive view. The rotation of this ice circle is barely perceptible until the video goes into timelapse mode, and then the spin becomes quite obvious.
It’s amusing to watch the birds flying from one part of it to another as it continues to spin around.
Ice circles are most frequently seen in Scandinavia and North America. But occasionally they can pop up elsewhere, too. One was observed in Wales in December 2008 and another in England in January 2009.
This one, though, by quite a clear margin, appears to be the biggest ever reported. The previous known record was a 160-foot ice circle found in 1987 in Pite River, Sweden.
[via Laughing Squid]