Based on the impact craters found in and around these valley networks, scientists say that a majority of the Martian valley networks were formed around 3.7 billion years ago or earlier. A few are relatively young too – evidence suggests that they may have formed about three billion years ago. But there is still a lot of confusion regarding how exactly they were created! There are mainly three theories.
The first is that rain- or snow-fed streams of liquid water once used to flow across the Martian terrain creating valley networks that look very similar to the ones we have on the Earth. For this, Mars had to be a warmer and wetter place than it is now, with a thicker, carbon dioxide-rich atmosphere. But looking at the climate of Mars today (and many other factors), scientists are unable to fully explain how this could be.
The second is that these channels were created by the flow of groundwater beneath the surface. This process, known as “sapping,” may have happened when the cold Martian ground got heated by volcanic or impact events. The third theory is that the water that carved at least some of the valley networks on Mars, did not flow in the open, but under glaciers which protected it from getting frozen.
Picture Credit : Google
