Found this link via Ellie’s World, what an interesting phenomenon (click to enlarge photo):
As I was checking out Amasa salt shed a nearby resident pulled up to me and asked if I wanted to hear an interesting story. He went on and said that last night his neighbor was coming home from work at 12:45 am and noticed pulsating lights coming from the area were the Townline Road crosses the Hemlock River. He noticed these lights as he turned off US 141 onto Townline Road. As he approached the hill which breaks into the river basin, the lights disappeared. Thinking he was just going crazy he went home and went to bed.
The next morning he called the man I was talking to and told him what he had seen. Curious, he drove down to the bridge and found a perfect circle about 50′ in diameter cut into the ice and it was rotating in clockwise rotation.
As Shakespeare said, there are more things in heaven and earth than our dreamt of in our philosophy.