1010 - The Other Side of the Dunes

While you may not be walking on the park’s sandy beach, you are still among the sand dunes. So why are these dunes so far away from the lake?

Sand dunes form in repeating rows. Along Lake Michigan, these rows follow the shoreline as lake levels change. Long ago, when Lake Michigan was much higher, the dunes in front of you were being formed along its ancient shoreline. As the lake level dropped, new sand dunes grew in front of these and so on and so on. The new dunes in the front row are called foredunes. These older dunes in the back rows are called backdunes.

Because backdunes are shielded from strong winds by the foredunes, plants can grow on them more easily. Over time, forests take over, making the backdunes look like regular hills.

How are dunes formed?

As strong winds come off Lake Michigan, they bring grains of sand with them. Once the wind slows or encounters an obstacle, it drops the sand and creates a pile. This pile grows over time, eventually forming a dune.