Glacier Shear Margin

View of a glacier shear margin seen from the NASA DC-8 on the Nov. 1 survey of the Ronne Ice Shelf grounding line. A shear margin is the point where fast-flowing glacier ice meets slow-moving ice or rock (in this case, ice attached to the Dufek Massif in Antarctica’s Pensacola Mountains). Credit: NASA / Maria-Jose Viñas