i.e., What caused such a special and unique place?
A plug: The Web Soil Survey
Soils map of area north of Worster Lake
By this time the glacier's long gone
A glacier gone as far as it's going to go
Kankakee and neighboring watersheds
The Kankakee Watershed
Watersheds of the Kankakee and its Tributaries
*Dominant during the settlement period
". . . . ingested calamus may be toxic – leading to its commercial ban in the United States."
This plant produces edible tubers that have traditionally been extensively used by Native Americans.