Some moron on a news site where people comment afterwards said it was a hoax and that someone got out on the ice and cut a circle. Obviously the man has never been on river ice. LOL

For me I'm surprised it doesn't happen more often. Seems to me all it takes is an eddy and floating chunks of ice that spin until they form a circle. If there are any edges that are irregular or stick out the surrounding ice will grind them off.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.