The last advances of the glaciers, the Port Huron and Valders substages of the Wisconsin ice sheet, followed valleys carved out by earlier, larger glaciers and further gouged the valleys. The last of the glacial ice melted away from this area 10,000 – 14,000 years ago.

Headlands, interlobate moraines from earlier, larger glacial ice lobes, such as Pyramid Point, Sleeping Bear Plateau, and Empire Bluffs steered more recent glacial ice into Good Harbor and Shell Lake, School Lake, Lime Lake, Little Traverse Lake; Sleeping Bear Bay and Glen Lake; Platte Bay and North and South Bar Lakes and Platte Lake.

As glaciers receded, sometimes, huge blocks of ice like icebergs would break off from the receding glaciers and became surrounded and covered by gravel, sand and debris from the glacier. Later, as these ice blocks melted, a great declivity, often conical, would be formed as the material covering the ice block collapsed. These huge depressions are called kettles. There are many of these throughout Michigan and there are several in the park.

As glaciers melted, the Great Lakes basins filled with water. As ice rapidly melted from the ice lobe in Sleeping Bear Bay and could not flow north because of the remaining ice, a river carried this water south from where Glen Lake is now, along where M-22 is now, around Empire and finally into the Lake Michigan Basin by Otter Creek. A look at this glacial drainage channel (now dry of course) where it crosses M-22 at Stormer Road, gives one a concept of the immense volume of melt water it once carried.

Wave action over thousands of years, from Lake Michigan and other earlier, greater lakes that filled the basin truncated the morainal headlands so that they now appear as great headland bluffs. Thus we see at Empire bluffs, the Sleeping Bear bluffs and Pyramid Point, the steep sand and gravel faces so prominent along the shoreline. This process continues so that, especially during years of high water levels in Lake Michigan, great masses of these bluffs all along the shoreline collapse into Lake Michigan.

North Bar and South Bar Lakes near Empire are embayment lakes and on a grander scale, so are Glen Lake and Crystal Lake. The lakes were formerly embayments of the higher Lake Algonquin, preceding Lake Michigan. The embayments were formerly open to the larger lake but were cut off by sand moving steadily along the shoreline even as the lake was receding.

This action can be seen today along the Lake Michigan shoreline. The prevailing winds are from the southwest and generate waves that move north along the shoreline. Each wave and wave after wave, passes a child’s sand shovel-full size of sand to the north and the next wave does the same and the next the same; passing it on, passing it on. Storm waves move big shovels-full of sand to the north; wave after wave.

The Lake Michigan shoreline is constantly changing. Headlands are being cut away; bays are being filled in. The forces are ever in the process of straightening the shoreline. There have been huge landslides at Sleeping Bear Point and Pyramid Point over the years. During periods of high water levels of Lake Michigan, you may see masses of the sand bluffs along Empire Bluffs slumping into Lake Michigan. As the ancient Lakes Algonquin and Nipissing, which preceded Lake Michigan, fell and Lake Michigan water levels receded, a series of old beach ridges remained. You can easily determine these ridges on topographic maps and aerial photos as arcs that parallel the present shapes of Sleeping Bear Bay, Good Harbor Bay, and Platte Bay. You can experience them if you walk toward the beach as a series of ridges and swales, dry and wet over and over. The Crystal River, as it passes from Glen Lake to Lake Michigan, flows between the ridges until it cuts through one of these old beach ridges and then doubles back until it cuts through another one and so on to the end. Some of the most prominent features in the park are the perched dunes. These are not ordinary beach dunes. They are high dunes perched on top of already high glacial moraines. The moraines are the great ridges of material carried along by the glaciers and pushed before them and then deposited when the glaciers were halted in their advance. As waves and wind along the lakeshore cut away the headlands of the glaciers, the wind blew the lighter sands higher up on top of the moraines. The heavier stones fell down toward the beach. This is a continual sifting process, which you can experience on a windy day from the Lake Michigan overlook on the Stocking Scenic Drive. You will see and feel the sand blowing upward and you may carry some of it away in your eyes, ears and hair.

When you are on the Sleeping Bear Plateau, you can observe hills of sand in great crescent shaped waves that move inland over time covering forests in front of them and exposing forests behind them, killed hundreds of years earlier by the moving dunes.

All of these awesome geologic forces happen over thousands of years. The Pleistocene Epoch, considered the Ice Age, may have lasted, according to geologists, 500,000 to 2,000,000 million years. The last great glacier that covered all of this land, the Wisconsin Ice Sheet, occurred 50 to 70 thousand years ago. This was preceded by earlier ice sheets, the Illinoian, the Kansan, the Nebraskan, EACH advancing over many thousands of years, EACH retreating over many thousands of years. The last of these, the Wisconsin, influenced the landform of North America north of the Missouri and Ohio Rivers.

Consider the changes in the landforms that have occurred over the great lengths of time and consider that they are continuing to change. Consider the power of ice, of water, of wind, and of the patience of time. Could Lake Michigan dry up? Could the Great Lakes be covered again by a glacier? Not in our lifetime but change happens day by day and year by year. Are we now in a post-glacial or interglacial period? How is the landform being changed by human activity? How is the climate being changed by humans today?