Seminar Series - Spring 2009

Ice-walled lake plains in northeastern Illinois archive fossils dating from the last deglaciation, a time when sparse tundra plants grew on the thin, rocky soils atop the Lake Michigan lobe. The basal radiocarbon ages from these lacustrine successions provide an estimate of when the ice began to stagnate. The time for moraine formation is the difference in the basal age of ice-walled lake seccessions on the moraine of interest and on the older, adjacent moraine. For example, 810 years is the conservative estimate of how long it took to form the Tinley Moraine (from 18,100 to 17,290 cal yr BP). Sediment flux of the debris forming the moraine may be estimated from detailed cross sections done by the ISGS Great Lakes Coalition Mapping Program. Depending on assumptions, the annual flux ranged from about 890 to 1,360 m3 per meter-width of ice flow. The values are the same order-of-magnitude as the greatest annual sediment fluxes estimated from modern sedimentary basins.

Other Seminars and Colloquia of interest on the UIUC Campus

Department of Geology

Department of Geography (check under Activities)

Department of Natural Resources and Environmental Science