Natural Artifacts Tumbling Along Beach

Emerging from Lake Michigan are natural spheres interlaced with debris. These artifacts of surf pounding a dune line are now decaying time capsules of a high-water era.

When the lake level rises, the crashing waves scour away at the edge of the dune, pulling the native Marram grass--and their incredible roots--into the surf.

There the long grass tumbles in the sand and combines with other disparate lake denizens, like Zebra mussels, string, feathers, and plastic.

Clods of grass, sand, and beach debris eventually form into spheres along the shoreline. When the waves subside, the dune grass balls emerge on the water's edge, beached just out of reach of the receding waves.

The past few years of high water have yielded a large crop of dune grass balls. They are a rising-water phenomenon, as crashing waves scour the edges and pull fresh material lakeward to tumble in the surf. Other iterations of sea balls occur around the world, caused by similar but not identical circumstances as here on the Great Lakes.

When lake levels drop and there is less wave action at the dune line, there will likely be less Marram grass churning offshore. The dune grass balls are artifacts of the shoreline around the time of high or rising water.

Some recovered dune grass balls are dense with sand and firm, while others are light and compressible. A pile eventually degrades, with the rain washing the sand downward. As the bottom retains moisture, the damp spheres become limp. In time, the organic material will decay and the pile of balls will become a lump of sandy compost interspersed with micro-trash.