Relatively little is known about the environments of central North America during the early and middle parts of the Wisconsin glacial period, which extended roughly from 70,000 to 25,000 years before the present. Few deposits of materials from the period remain; one of the most important formations that does exist is the Roxana loess, a fine, wind-blown material found in the upper Mississippi River valley. Scientists have disagreed about the origins of these deposits, however, with each alternative explanation providing markedly different interpretation of prevailing environmental conditions. This doctoral dissertation project will use geochemical, particle-size, mineralogical, and radiocarbon analyses to determine the source materials and age of Roxana loess deposits in the Mississippi River valley between LaCrosse, Wisconsin, and Rock Island, Illinois. The results of these analyses will be compared with comparable analyses of deposits from the Illinois River valley to determine whether the loess is composed of materials from local or from glacially transported sources, and the results will provide a firmer basis from which to infer large- and smaller-scale paleoenvironmental conditions and geomorphic processes during the early- and middle-Wisconsin period. This research will provide valuable information for scientists conducting geomorphic and paleoenvironmental research in the upper Midwest, and it will contribute toward reconstruction of regional conditions during the last ice age. The project also will provide an excellent opportunity for a promising young scholar to continue to develop independent research skills.
