The Laurentide Ice Sheet was the largest of the Northern Hemisphere ice sheets that developed during the last glacial maximum. An accurate reconstruction of this ice sheet has significant implications for late Quaternary paleoclimatic reconstructions, including interpreting global sea-level history. A significant point of debate concerning the dynamics and form of the Laurentide Ice Sheet involves specifying whether the dominant mechanism of ice movement was internal deformation, sliding, subglacial sediment deformation, or some combination of these. The fundamental question is whether rigid-bed processes, such as sliding, or soft-bed processes, particularly pervasive deformation, were dominant. This project will attempt to answers this question by developing aa numerical model of the ice-till dynamics of the Lake Michigan Lobe during the last glacial maximum. Parameters for sediment rheology derived from geotechnical analyses of glacial sediment will form the basis of the model, and they will be integrated with an examination of the sediment record and sediment transport fluxes of the lobe with respect to its dynamics. The model will test the deforming bed versus sliding hypotheses through a quantitative assessment of the physical conditions under which sediment deformation could or could not have occurred beneath the Lake Michigan Lobe. The results of this research will have significant implications for understanding and modeling the dynamics of ice sheets as well as for interpreting the origin of massive, homogeneous till units in mid-latitude regions. Understanding the dynamics and behavior of an ice sheet during its decay is important for constraining potential behavior of modern ice sheets.
Doctoral Dissertation Research in Geography and Regional Science