This award supports a project to develop a coupled thermo mechanical model for margins of ice streams of the type draining the West Antarctic Ice Sheet (WAIS). This model will provide a theoretical framework for interpreting measurements of velocity and ice temperature in ice stream margins in terms of changes in basal sliding behavior and ice flow law across the margin. This work will allow the investigation of the possible controls on the positions of ice stream margins, with particular emphasis on the stability of a boundary between a frozen and a wet bed. Since the width of ice streams affects the discharge of inland ice through the ice streams into the ocean, an understanding of ice stream margins is fundamental to understanding the mass balance of the West Antarctic Ice Sheet, how it might change in the future, and what impact it could have on global sea level.