Spatial Signatures of Soils and Sediments: Geomorphic Research on Silty Soils in the Midwest USA

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AbstractBCS-0422108Randall SchaetzlMichigan State UniversitySoil geomorphic research usually links field and lab work in soils and geomorphology to answer questions about landscape evolution. Working within that framework, this project will produce spatial data sets, i.e., detailed maps of mineralogical and textural characteristics, of soils developed in silty surficial sediments, for parts of the midwestern USA. Put another way, I will ascertain the spatial signatures of silty soils in three midwestern subregions and compare these signatures to areas of known loessial soils, to determine if the soils in each of these three regions have formed in silty loess - or some other silty sediment. Using these spatial signatures maps I should also be able to ascertain the source areas of the silts in these regions. The maps, created for three areas of "anomalous" silty soils in the upper midwest, form the core of the research. These areas, set within otherwise sandy landscapes, are (1) the Grayling Fingers and (2) the Buckley Flats regions of northern lower Michigan, and (3) the Peshekee Highlands in Michigan's Upper Peninsula (UP) and in the NE Wisconsin - western UP border area. In the field, using existing digital soil maps and a GPS, I will locate and sample soils that have anomalously silty textures within these three regions. Samples from these soils will then be taken back to the Quaternary Landscapes Research Group lab in the Department of Geography, for further analysis. Data from the soils and their parent materials, e.g., mineral amounts, colors, textures, particle shapes, lithologies, parent material thickness, etc., will then be then analyzed to determine parent material characteristics for each soil, quantitatively tying it to a specific parent material, i.e., giving it a sedimentologic signature. Maps of specific soils' sedimentological signatures are the spatial signatures maps that I refer to above. Ascertaining whether the silt cap on these soils is loess, which it is likely to be in at least one of the three regions, will be determined by comparing the spatial signatures of soils within each of the three regions to spatial signatures and characteristics of soils that will have already been sampled from the thick loess regions of western Wisconsin and NW Illinois. The data generated using this protocol should vary systematically and predictably across space, and may open new doors for research into landscape evolution that previously would have been fraught with insurmountable "data needs" obstacles. The synergies and knowledge gains that can be achieved from this research will stimulate new research on landscape evolution and provide opportunities for the scientific and lay communities to examine soils and sediment patterns in ways that have previously been impossible. The research will add to our understanding of wind-driven and soils systems that have operated in the upper midwest since the end of the last glaciation. This field- and lab-oriented research will also hone and expand a method that may become a standard for many soil geomorphology studies, providing a tested method for detailed resource mapping. This method may also assist soil mappers as they remap the region's soils and will heighten awareness of the utility of soil maps in geographic research. Finally, the research undertaken in this project will provide educational opportunities for several graduate and undergraduate students, as well as building the scientific infrastructure of MSU.