The glaciers left behind an ideal setting for building sand dunes: a sandy coast on the windward side of Lake Michigan.Prevailing westerly winds blowing across the lake build two kinds of dunes in Sleeping Bear Dunes.
Beach dunes develop on low-lying shores of Lake Michigan.Their main ingrediant is beach sand.
The Aral Dunes, along Platte Bay's north shore, are good examples of beach dunes.
Perched dunes, on the other hand, sit high above the shore on Plateaus.
Glacial sands atop these surfaces supplied material for these dunes.
The Sleeping Bear dune of Anishinaabek Indian legend is a perched dune.
Some dunes migrate, pushed by the wind.
Sometimes shifting sands bury trees.
As the dunes move on, ghost forests of dead trees are exposed, stark reminders of the dunes' passing.
Not even humans have escaped the influence of windblown sand.
U.S.Coast Guard buildings now in Glen Haven had to be moved from Sleeping Bear Point in 1931 because migrating dunes threatened to cover them.
Beachgrass and sand cherry are among the first plants to grow on newly built dunes.
They play an important role in dune development by acting as obstacles that slow sand laden wind and force it to drop its load.
Their roots hold sand in place and stabilize dunes.
But strong winds can strip plants from a dune and carve out a bowl-shaped blowout.