Radiocarbon dating procedures have been an important means of establishing the age of organic materials, such as buried soils. By dating materials, geomorphologists, archeologists, paleontologists, and other scholars can use modern evidence to reconstruct past patterns and processes. Different estimates of dates have been derived from different facets of buried soils, however, that uncertainty significantly limits the confidence that scholars may place in the conclusions drawn from examination of those materials. This doctoral dissertation research project will compare the dates of three characteristics of buried soils -- the humic acid, the humin (fine residuals), and the soil in its entirety -- from a set of samples gathered along the Republican River in southern Nebraska. Dates estimated by two independent laboratories will be compared to determine which types of dating procedures produce the most reliable estimates, which then will be used to estimate rates of soil formation and river deposition at the test site. Benefits from this research will be realized at a number of levels. Most specifically, the findings will permit a more detailed reconstruction of the soils and depositional history of the area. At a more general level, this work will provide greater insights into the accuracy of radiocarbon dating of buried soils. Although this analysis is based on an examination of alluvial soils from the Great Plains, the results will have value for scholars using other types of soils from other environments. As a result, this work will have positive impacts on a wide range of Quaternary inquiries.
