On a recent visit to Dickson Mounds Museum in Fulton County, Illinois, I spent some time on the rooftop observation deck. Here I found myself picking out distant landmarks along the Illinois River valley, repeating what I had done many times in the twenty-seven years since first traveling to the area for a job interview. With the sun’s direct rays on my face, I tried to imagine what the scene before me might have looked like a thousand years ago.
Over the last three decades, I have spent considerable time learning about the ecological changes that have occurred over central Illinois since the last Ice Age ended roughly 10,000 years ago: how the climate changed from the Pleistocene cold to a long, warm and dry period (when prairie first became established); then changed to cooling, warming, and cooling again (see page xi in Theler and Boszhardt [2003]); and how plant communities tracked these changes, from tundra to forest to prairie grasslands and savanna. Humans, who had been in Illinois for around 12,000 years, certainly witnessed all of those changes. Their stories are well told in the museum’s exhibits; in fact, a great deal of what is known about prehistoric Native American cultures came from the Illinois River valley. When I view the river valley from the museum’s rooftop, their stories, with only a bit of imagination, come alive.
Dickson Mounds Museum and Emiquon National Wildlife Refuge (foreground)
One landmark barely discernable from the rooftop is probably unknown by most folks viewing the river valley; it is a small, native sand prairie at Henry Allan Gleason Nature Preserve, ten miles to the northeast of the museum, across the river in Mason County. This is the site where Gleason himself, in the early 1900s, conducted foundational research on plant communities and succession. During this recent museum visit, the skies were clear and calm, and so I had little trouble finding the ridge of sand dune with golden brown prairie grasses that stood out against the surrounding forested hills. And I wondered whether Hopewell or Mississippian inhabitants of this area would have gazed toward the distant prairie as I did; or from the other direction, sighted a direct line to the village that once existed where the museum now stands.
Henry Allan Gleason Nature Preserve, early 1990s
I also thought about the influences human-set fires might have had on the wholesale plant community changes of prehistoric times until the prairies became fully established—those same prairies, like the one at H.A. Gleason Nature Preserve, that greeted the first Europeans who entered the Illinois country. We know from historical accounts that Native Americans burned the prairies, and tree ring analyses show evidence of frequent fires sweeping through savannas as well as forests. Today, experience has taught us that Illinois’ grasslands will eventually change to forest in the absence of periodic fire because the current climate—together with all of its variability over hundreds of years—favors forest. When did the practice of burning the landscape begin? Were people during the Archaic Period, roughly 10 to 3 thousand years ago, burning the landscape as the historic Native Americans did? Was this the ultimate factor which ensured that prairie would persist in central Illinois? Viewing the Illinois River valley before me from the H.A. Gleason Nature Preserve or from the Dickson Mounds Museum observation deck, I think that the answers to these questions lie scattered before me in thousand-year-old burial mounds and former village sites; artifacts from a martial, state-like society that vanished well before Europeans ever ventured into Illinois; and by the small, remnant prairies and other natural communities that have survived. Or maybe they more than likely have been scattered by the winds and erosion of too many years.
Ogden-Fettie Mound (Havana Hopewell - 300 B.C. to 300 A.D.)
All of this has given me a thoughtful appreciation of deep time and how the modern era is merely a data point on a long continuum of change, and my lifetime is even less. But some might ask why expend the effort to think of such things when planning for the future is what we should be doing and there are so many pressing issues of the day that demand attention. Concerning that viewpoint, I recall the classic bored high school student’s question about history: Why do we need to know this? I counter with a question: Why does anyone need to know anything? Louis Pasteur once said that Chance favors only the prepared mind. One can never know how a miscellany of facts may combine to produce an insight sufficient to shift a paradigm. Perhaps knowledge of the past may alert us to dangerous pitfalls before it is too late. Has it really been such a long time between the Clovis point and smartphone?
Selected References
Berkson, A. and Wiant, M.D., editors. 2001. Discovering Illinois archaeology. Illinois Association for the Advancement of Archaeology and the Illinois Archaeological Survey.
Gleason, H.A. 1926. The individualistic concept of the plant association. Bulletin of the Torrey Botanical Club 53:1-20.
Pielou, E.C. 1991. After the ice age. The University of Chicago Press, Chicago and London.
Struever, S. and F.A. Holton. 1979. Koster: Americans in search of their prehistoric past. Waveland Press, Inc., Propect Heights, Illinois.
Taft, J.B., R.C. Anderson, and L.R. Iverson. 2009. Vegetation ecology and change in terrestrial ecosystems. Pages 35-72 in C.A. Taylor, J.B. Taft, and C. E. Warwick, editors. Canaries in the catbird seat: the past, present, and future of biological resources in a changing environment. Illinois Natural History Survey Special Publication 30. Champaign, Illinois.
Tallis, J.H. 1991. Plant community history. Chapman and Hall, London.
Theler, J.L. and R.F. Boszhardt. 2003. Twelve millennia: archaeology of the upper Mississippi River Valley. University of Iowa Press, Iowa City.
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