60th Annual Report on Research 2015

The purpose of this project is to study the paleosols of the Upper Pennsylvanian to Lower Permian Dunkard Group in southeastern Ohio to develop a better understanding of the relationships between paleosol properties and local scale variations in hydrology, topography, parent material, and biota. In addition, these studies will be used to reconstruct the Late Paleozoic terrestrial landscapes of the Dunkard foreland basin and improve the understanding of the changing climate over this transitional interval of Earth history.

During second year of the project my students and I have undertaken field and laboratory work on multiple field sites with exposures of the Washington Formation and lower Greene Formation of the Dunkard Group in eastern Athens County, Ohio and western Wood County, West Virginia. These field areas have allowed the investigation of multiple coeval paleosols through these units; stratigraphic control has been provided by tracing individual paleosols across closely spaced outcrops, recognition of key coal beds, and distinct, laterally persistent sandstone bodies. We have constructed 10 detailed stratigraphic sections from these new localities and described multiple occurrences of four different types of paleosols from the outcrop and hand sample descriptions. Samples were collected for the preparation of thin sections as well as geochemical and clay mineralogical analyses. These analyses are currently underway. The field work has also resulted in the discovery and description of continental trace fossils, plant fossils, invertebrate fossils, and vertebrate fossils from the localities. The fossil specimens provide a critically important view of the fauna and flora that occupied the landscape surface and the subsurface. The body fossils, in particular the plants, also provide additional stratigraphic control for each of the field sites.

Newly described paleosols formed on the proximal to distal floodplain of a meandering to anastomosed river system. The paleosols occur within repeating cycles bounded by medium- to coarse-grained sandstone bodies and show a trend of forming in environments proximal, distal, and finally proximal to the active channel. The paleosols include Entisols, Inceptsiols, Histosols, and, predominantly, Vertisols that show strong influence by autogenic processes; this has been recognized from lateral variation in coeval paleosol properties within and between outcrops. These variations include development of horizons, development of peds and cutans, presence and composition of nodules and concretions, and depth of rooting and burrowing. Lateral changes in topographic relief, drainage conditions, and soil organisms appear to have had the greatest degree of control in altering these paleosol properties across space. Despite these variations, however, major features of the paleosols, including those that help define their paleosol orders, were consistent across coeval units.

The second year of this grant has involved the participation of two undergraduate students and one graduate student in the Department of Geological Sciences at Ohio University. The students conducted research at the field localities, measuring sections, describing hand samples, and collecting samples for laboratory analyses. Results of this research have been presented in two talks, one given by a former graduate student, at the 2014 Geological Society of America Annual Meeting in Vancouver. Since the start of the grant, two graduate students have graduated with Masters of Science degrees in Geological Sciences (2014 and 2015) with thesis projects involving paleosols of the Dunkard Group. The results of these projects are described in three manuscripts currently in revision or preparation.

At the start of the third year of the grant, I have one new graduate student and two new undergraduate students that have started to work on the project. We are in the process of reviewing the work that has already been conducted over the last two years and investigating new field localities.