January 2016 in Southwest Michigan, and the ice has finally begun to form along the lakeshore. While high winds and waves have not yet encrusted the lighthouses in ice, shelf ice is beginning to form on the beach and piers in South Haven.
The waves roll chunks of snow and ice together until round balls of ice form in the water. A very similar process happens to rocks in rivers and oceans- they're tumbled against other rocks until the edges are smooth and round. This is the same process, only much faster.
The chunks of ice we encountered today ranged from softball size all the way up to beach ball size - two feet in diameter. These chunks float in Lake Michigan until the waves carry them up onto the beach, piers and shelf ice. This is the process that builds the mounds of shelf ice seen along the beaches of the Great Lakes. I've seen these chunks thrown up onto the 15 foot high shelf ice by the churning waters of Lake Michigan, some must weight a couple of hundred pounds.
A few more weeks of cold weather, and the shelf ice may extend hundreds of feet into the lake. As tempting as it is to venture out onto the shelf ice, DON'T DO IT, it can be deadly. Read my Huffington Post article on the dangers of shelf ice: The Winter Shore: Beautiful but Potentially Deadly.