[medved]

Back to the question of canyons and rivers... you guys might find this interesting, I doubt that a "piltdown_woman" would comprehend it. There isn't anything else like the Grand Canyon on Earth, but there is on Mars. Valle Marineris is an electrical arc crater thousands of kilometers in length which shows the same kind of fractal topography which the Grand Canyon does.

[Junior]

Interesting that "First Law of Computing: Garbage in = garbage out" appears on the first page ...

But, anyway. The Mariner Valley on Mars simply shows the effects of water erosion. There is lots of evidence for water erosion on Mars.

Besides, the Belgians never mentioned finding any fulgarites among the gumme plantations in the area [1].

[1] This is an obscure reference to a defunct RPG known as Space 1889. It's one of the first Victorian Science Fiction Games to hit the market and it's a real hoot.

[Aracelis]

I doubt that a "piltdown_woman" would comprehend it. There isn't anything else like the Grand Canyon on Earth, but there is on Mars.

Really? An "electrical arc crater"??? What an interesting idea, and here I thought you came up with that hypothesis yourself.

Sorry to burst your self-imposed bubble of disinformation, but there is evidence that liquid water once flowed across the surface of Mars, and that Valles Marineris was probably cut by water...just like the Grand Canyon.

But please, continue to champion the oddball hypotheses. Your arguments are at the very least diverting.

[Doctor Stochastic]

There isn't anything else like the Grand Canyon on Earth,...

There's the Barranca del Cobre. It's not like the Grand Canyon exactly; it's bigger and deeper and prettier.

Not to mention the Gorges du Verdon (a bit smaller.)