Lake in the Hills Fen
an Illinois Nature Preserve
When water seeps
out on a hillside,
a hanging fen is
formed. The water
flows all year, even
under the icy
surface in winter.
Below the fens, wet
conduct the water
to Crystal Creek,
which runs through
the center of the
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.
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.