The sediments beneath fast-flowing ice streams change dynamically within decades, reports a study published online in this week's Nature Geoscience. The work shows conclusively that elongated ridges in the sediment bed ― called mega-scale glacial lineations ― are characteristic of regions of fast ice flow.

Edward King and colleagues collected radar data that reveal the ice-sediment interface beneath Rutford Ice Stream, a glacier in West Antarctica. They identified mega-scale glacial lineations in the sedimentary bed that have identical characteristics to sediment beds of ancient ice sheets. Using seismic data, the researchers conclude that beneath fast-flowing ice streams the sediment bed changes relatively quickly. Most of the discharge from large ice sheets ― such as the one covering Antarctica ― is channeled through such fast-flowing streams, and the properties of the underlying sediments can affect the speed of ice flow.

In an accompanying Backstory, Edward King writes about his experience of camping in Antarctica to collect the data.