A foam layer cake spins in a pothole on the Presque Isle River before flowing into Lake Superior. Porcupine Mountains Wilderness State Park, Michigan, USA.
A foam layer cake spins in a pothole eroded into Nonesuch Shale rock on the Presque Isle River before flowing into Lake Superior. Porcupine Mountains Wilderness State Park, Michigan, USA. Tannins leached from Cedar, Spruce and Hemlock trees color the water amber and brownish green. Churned soft water (having low mineral content) creates much foam.