Lake in the Hills Fen
an Illinois Nature Preserve

Hanging Fen
When water seeps out on a hillside, a hanging fen is formed. The water flows all year, even under the icy surface in winter.

Sedge Meadow
Below the fens, wet meadows slowly conduct the water to Crystal Creek, which runs through the center of the preserve.

Calcareous fens are wetlands fed by ground water flowing at or just beneath the surface. They are formed when rain falls on the hills and percolates for miles through the gravelly soil before seeping out on the side or at the base of a hill where the water table has been exposed by erosion. During this journey the water becomes saturated with calcium compounds and turns alkaline. Only specialized plants, many of them rare, threatened, or endangered, can tolerate this mineral-laden water.

Gravel Hills
Because of the gravelly soil left by the glaciers, the hilltops are very dry. Only the most drought tolerant plants, such as this shooting star, can survive here.

Over 400 species of plants, 80 species of birds, 40 species of butterflies, and a myriad of other animals depend on this preserve for a place to live.