Spanning nearly 435 miles across the surface, the valley stream is named Nirgal Vallis and experts said it was shaped by flowing water and impacts
Spanning nearly 435 miles across the surface, the valley stream is named Nirgal Vallis and experts said it was shaped by flowing water and impacts
Scientists believe that Nirgal Vallis formed in a similar way to morphologically similar valleys we see on Earth. As there appear to be no branching, tree-like tributaries feeding into the main valley of Nirgal Vallis, it is likely that water was replenished on ancient Mars by a mix of precipitation and overland flow from the surrounding terrain.
The system may also have its roots in a process known as groundwater sapping: when water struggles to travel vertically through a medium, and so instead continually seeps laterally through material in layers beneath the surface.
We see this kind of mechanism on Earth in environments where surface material is very fine and loose and thus difficult for water to penetrate – largely silty, sandy, unconsolidated, and fine-grained environments, where lower layers of the surface are permeable and friendlier to water than those above.
I am not a geologist, so what do I know, but it seems to me like these large rivers come to stubby upstream ends with no real signs of smaller tributary rivers and streams flowing into them. It doesn’t seem consistent with being water carved.
I had heard theories years ago that the mars ‘canals’ were actually the result of the crust cooling, perhaps at such a rate that it left the surface ‘cracked’.
But honestly I have no idea.
like a lava flow Positive, rather than a river bed negative.