The Topography
This region, known as the Wisconsin Driftless Division, was bypassed
by the most recent glaciers. Some scientists think that calving of glacial
ice in deep Lake Superior prevented glaciers from moving south into the
driftless area.The rugged landscape of northwestern Illinois shows the
effects of hundreds of thousands of years of erosion by rivers and streams
without the smoothing action of glaciers.
The Soil
Soil takes time to develop. The soils in this area formed in loess.
Loess is ground up rock—sediment from glacial meltwater streams that
was picked up and deposited by wind on nearby land surfaces. The loess blew
into this area during the Ice Age.
The Spring
This area is one of the four major karst regions of Illinois. Rain and snowmelt
flowing through crevices, caves, and along bedding plains, emerges in
seeps and springs at rock outcrops.