Ancient Riverbed in Stygis Catena (Original NASA/MGS/MSSS b/w Frame)

Caption NASA originale:"This MGS-MOC image shows a Trough (trough---> canale) in the Stygis Catena Region, East of the Martian Volcano Elysium Mons. The Trough probably formed by collapse (collapse--->geol. "cedimento" del terreno). Large, dark Boulders can be seen on the Trough Floor in this Volcanic Region. The image is located near 24,4° North Lat. and 210,4° West Long. The image covers an area about 3 km (approx. 1,9 mi) wide and sunlight illuminates the scene from the lower left".