THE GLACIAL STRATIGRAPHY OF THE ROCKVILLE, MINNESOTA TERMINAL MORAINE AREA

The Rockville, Minnesota area is a terminal moraine that includes sediments from the Superior Lobe, the Des Moines Lobe and the Rainy Lobe. The area investigated is a Late Wisconsinan, glacially developed topographically high feature, flanked on all sides by glacial sluiceways with kettle lakes. The higher areas on this feature contain irregular topography which suggests the possibility of glacial thrusting. Evidence of thrusting is also supported in the layering of sediments found in the well logs. At several locations, there is a red till cap on top of a yellow-red sandy outwash. The yellow-red outwash is slightly reactive to acid. A carbonate count and lithological analysis of the 1-2 mm grains will determine the most likely lobe of origination for these sediments. In the locals investigated, much of the strata appears to be a reworked interstratification of the Superior and Des Moines lobe deposits. The Rockville area feature appears to result from several advance and retreat actions of the major glacial lobes.