Correctly representing grounding line dynamics is of fundamental importance in modeling marine ice sheets.We have developed a groundingline discretization based on the Chombo embedded-boundary cut-cell framework.This promises better representation of grounding lines vs.a traditional stair-step discretization on Cartesian meshes like those used in the blockstructured AMR BISICLES code.Also,the fundamental discontinuous nature of flow across the grounding line is respected by treating it as a material phase change.