Huge Ice Spheres Along Sleeping Bear Dunes National Lakeshore
March 08, 2013
Photographer: Leda Olmsted
Summary Authors: Andrew McFarlane; Leda Olmsted; Jim Foster
Goodness gracious, great balls of – ice. The photo above shows the amazing arrays of ice spheres that accumulated along Sleeping Bear Dunes National Lakeshore on the northeastern shore of Lake Michigan in late February. They’re about size of basketballs and weigh up to 50 pounds (23 kg). According to Tom Ulrich, Deputy Superintendent from the Sleeping Bear Dunes National Lakeshore, these balls turn up on beaches during the winter with some regularity but they seldom attain this size. The balls tend to form where water turbulence breaks up a layer of slush. Mattes of slush and frazil ice accrete in the turbulent, supercooled water. Where the wave action is strongest, typically near-shore, slush and frazil evolve into spherical lumps. If conditions are just right, they’ll continue to grow until waves push them ashore. They’re somewhat akin to rock concretions in a cliff that form around a fragment of shale or sandstone. The concretions eventually erode out and roll down toward a low-lying spot. Photo taken on February 21, 2013. Click here to watch the video from UpNorthLive with Leda.