MAPPING LOESS DEPOSITS AND SOIL TYPES ON THE BIG STONE MORAINE IN MINNESOTA TO DETERMINE A POSSIBLE CORRELATION

Loess deposits of substantial thickness and extent have been studied and mapped in several locations in southern Minnesota. In west central Minnesota, however the extent and age of loess deposits is not well known. For this study, loess deposits were identified in previously unmapped locations in association with the inner and outer Big Stone Moraine, an end moraine formed during the last retreat of the Des Moines lobe. The goal of this research is to determine the age of this loess deposit and to determine specifically during which glacial event it was formed. Mapping of loess deposits is limited by the number of exposures that were encountered, so this study attempted to determine if soil types can be used as an indicator of the presence of loess.

Loess deposits were located and measured in 5 counties in west central Minnesota: Stevens, Swift, Pope, Big Stone and Grant. Locations were then plotted on digital county soil surveys. Soil types associated with loess deposits were then noted and compared. A 1:100,000 map of loess locations and associated soil types was then generated. Of the 21 data points created by the GPS coordinates of the gravel pits, 11 exposed loess deposits were found to be correlated with Renshaw, Sioux, Estelline, and Langhei Series. The Renshaw and Sioux Series show strong correlation with the plotted presence of loess demonstrating a relationship that may be useful in future studies.

Research for this study was funded by a grant from the N.S.F.-R.E.U Program (NSF-EAR-1262945).