The formation of Valles Marineris was a puzzle that left many scientists scratching their heads. Erosion by an ancient melting glacier? Tectonic action? Volcanic activity? Theories were many. But what everyone agreed upon was that the story of this canyon system was closely tied to the history of the Tharsis region!
Around four billion years ago, when Mars was at its ‘volcanic’ best, enormous quantities of magma collected underneath its north western part. The ground swelled up to form the Tharsis bulge. Over the years, as more and more lava spilled out, volcanoes grew in size to become giants like the Olympus Mons, Ascraeus Mons, Pavonis Mons and Arsia Mons. Finally, the pressure build-up was so great that it cracked the Martian crust! These fractures expanded in time, forming the system of chasmata that we know as the Valles Marineris – this is the commonly accepted theory today.
These cracks also released the water stored below the Martian surface. The escaping fluid washed away the sides of the chasmata making it still wider. The channels found in chaotic terrain on the eastern end of Valles Marineris may be the result of such flooding events. But we still don’t have all the details. Was it a single large flood episode followed by smaller ones later, or a series of floods within a short period of time? Nobody knows!
Picture Credit : Google
