That is all very exciting and offers a broader spectrum of opportunities for creation of circular mountains, craters, channels and rilles. The environment of this crater between the strange network of rilles at Hephaestus Fossae and the Hebrus Valles is a real challenge. I wonder about the following:
Example 1: https://www.google.de/maps/space/mars/@ ... a=!3m1!1e3
Here we can see that shallow "channels" with islands of material turn into sharply defined, deep rilles.
Example 2: https://www.google.de/maps/space/mars/@ ... a=!3m1!1e3
Here we see deep rilles and pits are crossing, disturbing and overwriting older shallow channels.
I understood that in the "subtraction hypothesis" electric arcs are removing existing material, they excavate material and create craters, rills, pits etc.
In the "addition hypothesis" (what mode, mostly dark mode???) the shallow "channels" are rather locations of "conveyor belts" for material or "cleaned regions" and craters results of swirling material which becomes concentrated in circular patters.
Now I wonder if both processes could work together. I think if a celestial object approached Mars then discharges should develop so: dark mode --> glow mode --> arc mode --> glow mode --> dark mode. For example arcs could cause craters and other processes could modify the original results in the landscape by the transport of material to other places and overwriting of earlier patterns.
O.K. sounds not very helpful.
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