Andreas Bauder, Dave M. Mickelson, Shawn J. Marshall and Patrick M. Colgan
 

The southern margin of the Laurentide ice sheet (LIS) is dominated by the presence of relatively thin and sensitive reacting ice lobes. Extent and dynamics is highly influenced among other factors by subglacial conditions, permafrost interaction, and the existence of the Great Lakes.Experiments with two-dimensional flow-line models applied on individual lobes showed that sensible tuning is needed. The three-dimensional thermomechanical UBC ice sheet model is now being used to investigate the spatial distribution of subglacial conditions and interacting lobe dynamics. The model contains thickness evolution, ice flow, temperature evolution, isostasy, and basal processes including the thermal regime of the bed. The time dependent evolution of the whole LIS is calculated for the last glaciation cycle with primary attention on correct reconstruction of the southern margin. The sensitivity of subglacial process assumptions was examined and compared with major results from the flow-line modelling. The transient physical conditions are being analysed with the aim of better understanding the reasons for the distribution of landforms produced by the southern LIS.