Gibson Woods Nature Preserve protects the largest remaining example of a rare landform known as “dune and swale”. Many thousands of years ago, Lake Michigan extended into this area, and as the lake receded, it built and left behind a series of dunes along its edge. Now mostly destroyed, these dunes once extended lengthwise for miles, roughly parallel to the present-day lake shore. Between each adjacent pair of dunes was a low area, or swale. The result somewhat resembled a giant washboard, with dunes and swales paralleling and alternating with each other. Aerial photographs reveal a striking striated pattern wherever the landform survives. The swales are usually wetter than the adjacent dunes, and the variation in soil moisture fosters unusually high species diversity.
The trail system resembles a large figure eight with a couple of short access trails. In general, trails follow the dune ridges, and when the paths cross from one ridge to the next they do so by spanning the swales on short boardwalks. Like the landform, the principal ecosystem here - black oak savanna - is quite rare. Occasional controlled burns keep non-native vegetation in check. In addition to black oak, look for interspersed prairie plants and prickly pear cactus. State-endangered Franklin’s ground squirrels live here, but don’t expect to see one; you’re much more likely to encounter gray squirrels and, in the warmer months, mosquitoes.
TRAIL MAP (Click to enlarge)