More than 5,000 years ago, post-glacial Lake Nippissing (now Lake Michigan) was nearly 30 feet higher than the present water surface. Before that time, glacial ice blocked the escape of water from the lake, but as the ice melted and the water level fell, the shoreline of the lake moved south and east. At the shore, breaking waves scooped up and re-deposited the sandy bottom, forming a series of parallel underwater ridges and troughs. As the water surface fell, the ridges became long, low sand dunes, with the troughs or swales alternating between them. Fourteen such ridges and swales, the ancient lake shorelines, are the geological foundation of the Woodland Dunes preserve. These forested dunes and swales provide a biologically rich habitat which is found in only two places (the other being nearby Point Beach State Forest) in our ecological region.
Over time, the bare sand dunes and wet swales were populated by a beach dune plant community, then shrub carr, then a rich forest composed of many plant and animal species. Both animals and early native people walked the backs of the sandy ridges, and some of our trails follow those ancient routes. Significant Native American villages were located nearby at Two Rivers and Shoto, on the East and West Twin Rivers. When European settlers populated this area, the land that is now Woodland Dunes was used for timber and wildlife harvest, recreation, and agriculture. Hemlock bark was harvested for tanning leather. A fish camp was built along the West Twin. A pavilion, site of picnics and brass band concerts for local residents, was built in the forest.