Pluto’s ‘Fretted’ Terrain
http://www.nasa.gov/feature/pluto-s-fretted-terrain
New Horizons scientists haven’t seen this type of terrain anywhere else on Pluto; in fact, it’s rare terrain across the solar system – the only other well-known example of such being Noctis Labyrinthus on Mars. The distinct interconnected valley network was likely formed by extensional fracturing of Pluto’s surface. The valleys separating the blocks may then have been widened by movement of nitrogen ice glaciers, or flowing liquids, or possibly by ice sublimation at the block margins. Compositional data from New Horizons’ Ralph/Multispectral Visible Imaging Camera (MVIC), shown in the bottom image, indicate that the blocks are rich in methane ice (shown as false-color purple); methane is susceptible to sublimation at Pluto surface conditions.
