About Indiana Dunes National Lakeshore/Pinhook Bog
The national lakeshore's Pinhook Bog consists of about 580 acres -- 145 of which make up a floating peat mat. A "moat" -- about 45 acres of wetlands -- separates the bog proper from the surrounding upland habitat.
Pinhook Bog is a unique natural area within the national lakehore. Pinhook Bog is open for ranger-guided tours that are quite popular and frequently require a reservation. The bog is very fragile and must be protected from overuse so the national lakeshore has gated and locked it. The only access into Pinhook Bog is along a one-quarter mile boardwalk designed to protect the fragile floating peat mat and rare flora and fauna. Insect-eating plants and orchids may sound like things found in a tropical rainforest, but you will find both at Pinhook Bog. You can walk on a mat of floating peat and vegetation -- like walking on a waterbed.
A bog is a special kind of wetland. About 15,000 years ago, a retreating glacier dropped off a big chunk of ice that created the bog's three basins -- the deepest of which is 45-foot -- lined with waterproof clay. The ice melted and filled the basins. Rain and snow and runoff from surrounding areas are the bogs's only sources of water. The basin is not fed by streams and the clay liner keeps out groundwater. Water leaves the bog only through evaporation and by plants giving off moisture. So the bog is different from a swamp, marsh or pond. Only special plants grow in its stagnant, acidic, nutrient-poor water. The top layer of the 145-acre floating mat consists of sphagnum moss, a stringy, delicate, light-green moss that absorbs up to 18 times its weight in water. Indians and early settlers used it in bandages and babies' diapers. The underside of the mat is peat -- partially decayed sphagnum and other vegetation. Trapped water and liquefied peat lie under this 1-2 yard thick mat. The floating mat supports the special shrubs and trees that grow here. Many open water ponds jot the surface of the mat. Over time, solid peat may fill the bog, more typical land plants will grow, and it will no longer be a bog. Three kinds of insect-eating plants, which get nutrients from their prey, grow in the bog: pitcher plant, sundew and bladderwort. These plants have adapted to survive under conditions where most other plants could not.