Eventually, sand from the rivers and currents created large sand bars that cut off the bays from the lake. Hamlin Lake in Michigan is an example of an inland lake that was once a bay in the Lake Nipissing time period. Sand dunes support a unique ecosystem, which develops in a succession, the process of one plant community replacing another over time. Shrubs then take over the dune, such as red osier dogwood and sand cherry, and they stabilize the dune until trees are able to take root. Eventually, the dune will evolve into a forest.
Dunes are also the home for many endangered and threatened animals and plants.
The piping plover , a small shorebird, nests in the shoreline sand, often in the protection of a perched dune. Houghton's goldenrod, pitcher's thistle, and the dwarf lake iris are all examples of threatened plant species that live on the Great Lakes dunes. Beach dunes develop on the low-lying shores of Lake Michigan, and they consist mostly of sand. The Aral Dunes along Platte Bay on Lake Michigan are examples of beach dunes. Perched dunes , such as Sleeping Bear Dunes along Lake Michigan and the Grand Sable dunes along Lake Superior, sit on a plateau high above the shore.