Ice stream shear margins are the border between very fast flowing and very slow flowing ice in Antarctica and Greenland. Shear margins hold back the fast flowing regions, kind of like a brake on ice loss and sea level rise. But the friction that comes from this brake warms up ice and lowers the viscosity, making ice flow faster. These seem like contradictory statements. How could the brakes weaken the ice and make it flow faster? In shear margins, multiple processes are competing and feedbacking with each other to create complexity at multiple scales. Ice sheet models that try to predict sea level rise struggle to account for a lot of shear margin processes. In our work, we try to capture these processes completely in a simple shear margin, so that we can help the performance of predictive models. We take a particular interest in the way that the ice surface changes over time and how this might influence the shear margins.