I first heard about kettle lakes at a presentation by Loreen Niewenhuis (1,000 Mile Walk on the Beach) at the South Lyon Library. Kettle lakes were formed when a piece of glacier broke off. The glacier melted, and the sand, silt and gravel accumulated on the glacier's travel fell in, and a deep lake was formed. Most of the lakes in Michigan are kettle lakes. 27 are 100 feet or deeper. Six of these deep lakes are in Oakland County. Cass (125 ft. deep), Dunham (118 ft.), Maceday (118), Orchard (111), Union (110), Walnut (101). The photograph here from MSU is of kettle lakes at Grange Hall Road and Dixie Highway. I love these geological tours of Michigan. We're fortunate to live in a state with abundant natural wonders to enjoy.