|This ice disc that recently formed in North Dakota|
has gotten a lot of attention recently. Another
nice one formed in Vermont in 2010.
It's a perfectly symetrical circle of ice slowly rotating in the river. As bits and pieces of river water froze in the cold snap, the ice got caught in an eddy and formed the rare phenomenon.
Ice discs don't form often. They need the perfect combination of the right temperature, the right force of current and a gentle eddy to form.
That combination apparently doesn't happen very often.
As I said, just about every major media outlet has mentioned the North Dakota ice disc. It's such a media hog
A similar ice disc in Vermont got a lot of local attention in 2010, but for some reason didn't become an "A" list celebrity like that one now out there in North Dakota.
But the Vermont disc, recorded along a river in Moscow, Vermont in February, 2010, lives on when you check out YouTube. Here's the (less) famous Vermont ice disc from that winter: