To fully appreciate the ecological significance of the Boone Creek Watershed, one must first understand its glacial origins.  The Boone Creek valley was created during the retreat of the Wisconsin icesheet some 10,000 years ago.  As the glacier advanced and retreated across northeast Illinois, it laid down a series of moraines consisting of sands, silts, and gravels.  When the glacier melted, vast lakes formed between the moraines and the retreating icesheet. These glacial lakes sometimes burst through “weak spots” in the moraines.  The resulting floodwaters carved out many of the river drainage systems we see across the Illinois landscape today.  Geologists term these events “catostrophic floods”.  Kettle topography is also another interesting feature of this young glacial landscape.  Kettles are bowl-like depressions formed when huge blocks of ice broke off the leading edge of the glacier.  As the ice blocks melted, kettle depressions formed beneath them.  If the kettle was low enough in elevation - a lake formed within it.  If the kettle was high up on a moraine - it remained dry, but functions as an efficient conduit for funneling precipitation into the ground water system. Thus, the forces of water and ice formed all the physical features of the Boone Creek Watershed - the hills, the ridges, the knolls, the kettles, and the valley floor.  These features are all the result of water and ice moving across the landscape - sometimes very slowly and other times with incredible speed.  This topography was, and remains, the template upon which a rich mosaic of plant life evolved as the climate warmed during the past few thousand years.

In the millennia that followed, native flora colonized the newly formed landscape as the glacier receded.  At first, spruce forests and other tundra vegetation dominated the landscape.  However, as the Illinois climate warmed, oak woodlands and prairies became established.  Oak woodlands prevailed on the steep slopes of the valley, while prairies prevailed on the more level terrain of the valley floor and on some ridge tops.  Oak savannas prevailed on the gentle rolling terrain within the watershed.  Native Americans had a profound influence on this landscape.  Fire has long been considered by ecologists to be an important natural disturbance mechanism for maintenance of the Midwestern prairie peninsula.  In the absence of fire, Midwestern prairies often become forested communities because the climate provides enough annual rainfall for tree growth.  However, trees have a very difficult time becoming established within fire maintained ecosystems.  As such, fire must have been an important component of the natural landscape, otherwise, forests would have overtaken the prairies long ago.There has been considerable debate as to the ignition source for Midwestern Prairie communities.  Some fires could have ignited by lightning strikes, but most conflagrations are now thought to have been the handiwork of Native Americans.  Many early historians and settlers wrote about the “Indians” who set fire to the prairies for purposes of hunting and warfare.  It is also thought that fire was simply a very powerful force by which Native Americans wielded some control over their environment.  As such, Native Americans viewed fire much differently than we do today.  They viewed fire as a natural force that provided many benefits and they certainly would have expended little or no energy to suppress wildfires.