Seminar Series - Spring 2008

"Probably no landform of similar size [Mima mounds] has occupied such a conspicuous place in geological controversy.⁵
"... the enigmatic origin of these mounds constitutes a continuous embarrassment and a challenge to geological science."⁶
"The small, low, flattened mounds of the lower Mississippi Valley are a problem for archaeologists."⁷
"Should one ask this writer if there is a truly perplexing, enigmatic aspect of lower Mississippi Valley Quaternary geomorphology that has defied concerted efforts at explanation and for which there is no consensus, he would immediately respond that the origin of [Mima] mounds clearly meet these criteria."⁸
The debate [on mound origins] seems endless."⁹

A recent article in Nature¹⁰ leads with the question: "Do biota affect landscape form and evolution?" Although that paper focused largely on the quantitative role of biota in mediating fluvial transport, the question posed in the article, and its title ("The search for a topographical signature of life") have broad and intriguing implications. The search for topographical and other signatures of life is a theme that, until recently, has been largely absent in the broad arena of Earth, biological, and environmental sciences. But new searches and researches are advancing the theme, with fruitful and useful discoveries being made. This talk summarizes our research along these lines.

We demonstrate how biomantle principles applied to both field observations and laboratory data (particle size, pH, organic matter, C-14 analyses/ measurements) do in fact reveal unequivocal topographic and landform signatures of life. We further demonstrate how these predictive principles aid in resolving long-standing cross-disciplinary issues, for example the origin of Mima mounds (pimple mounds, prairie mounds, etc.).

Our primary Mima mound work was at Mima Prairie near Olympia in Washington State, and at Diamond Grove Prairie near Joplin in Missouri. Supplemental researches and observations were made at multiple Mima moundfields across western North America over a multi-decadal timeframe. Moundfields were visited and revisited, examined and reexamined, some multiple times, in several cases annually over many years. New moundfields were predictively discovered. The sum of our collective research strongly indicates that Mima mounds are point-centered, locally thickened biomantles produced predominantly through bioturbation by small vertebrates. The process mainly involves repeated biotransfers and biosorting by the supremely fossorial members of Geomyidae. (The Dalquest-Scheffer-Cox model of nest-centered centripetal burrowing by these animals is supported.)

An unexpected bonus of our Mima mound research was to shed bright genetic light on another equally long standing and contentious landscape issue; the bioturbational origin of stone lines (stonelayers) in soils.

¹ Dept. Geography, University of Illinois, Urbana, IL 61801 USA, dljohns@uiuc.edu
²Geosciences Consultants, Champaign, IL 61820 USA, dn-jhnsn@uiuc.edu
³Illinois State Geological Survey, Urbana, IL 61801 USA, hongw@isgs.uiuc.edu, hackley@isgs.uiuc.edu, cahill@isgs.uiuc.edu
⁴Dept. Geography, Augustana College, Rock Island, IL jenniferburnham@augustana.edu
⁵Waters, A.C. and C.W. Flagler. 1929. Origin of the small mounds on the Columbia River Plateau. Am. J. Sci. (5th Ser.), v. 18, no. 105, pp. 209-224.
⁶Newcomb, R.C. 1952. Origin of the mima mounds, Thurston County region, Washington. J. Geol. v. 60, pp. 461-472.
⁷Fowke, G. 1922. Archaeological investigations. Smith. Inst., Bur. Am. Ethnol. v. 76, pp. 1-204.
⁸Saucier, R.T. 1994. Geomorphology and Quaternary geologic history of the lower Mississippi Valley, v. 1. Waterways Exp. Sta., Corps of Eng., Vicksburg, MS.
⁹Kaczorowski, R.T. and S. Aronow. 1978. The Chenier plain and modern coastal environments, southwestern Louisiana, and geomorphology of the Pleistocene Beaumont Trinity River delta plain. Field trip Guidebook, Houston Geological Society, Houston.
¹⁰Dietrich, W.E. and J. T. Perron. 2006. The search for a topographical signature of life. Nature v. 439, 26 January.

Other Seminars and Colloquia of interest on the UIUC Campus

Department of Geology

Department of Geography (check under Activities)

Department of Natural Resources and Environmental Science