Radio waves can be transmitted down through an ice sheet, ice stream or glacier and are reflected off the internal layers in the ice as well as off the bed. This reveals the internal structure of the ice, allowing scientsts to better understand the history of ice flow and test theories of how flow within ice sheets develops and evolves.
This image shows a 2km-deep cross-section of Carlson Inlet in West Antarctica. The layering is very different on the two sides of the image, to the left the layers are tightly folded and those to the right are gently undulating. This marks the difference between ice that is flowing fast (180m per year) on the left and slow (35m per year) on the right. The most intense folding is where the fast-moving ice shears past the slow ice.
Dr Ed King
British Antarcic Survey