Ice boulders on Lake Michigan shore

LEELANAU COUNTY, Mich. (WPBN) - A natural winter phenomenon is occurring on the shores of Lake Michigan.

Hundreds of ice balls, or boulders, are piled near Good Harbor Bay, which is part of the Sleeping Bear National Lakeshore, near Traverse City, WPBN reports.

The boulders are about the size of giant beach balls or basketballs, and weigh up to 50 pounds.

"It's not that it never happens and this is a once-in-a-decade thing. It happens more often than that. But these are very large and got bigger than they normally get," said Tom Ulrich, deputy superintendent from the Sleeping Bear Dunes National Lakeshore.

"The water temperature on Lake Michigan is just a little bit below freezing, so you get a small piece of ice that forms in the water, and as waves move back and forth it adds additional water, and freezes in layers," said 7&4 Storm Team Meteorologist Joe Charlevoix. "It gets bigger and bigger, and eventually you get big balls of ice that are pushed to the shore by the wind."