500 years from now when we try to make water flow on Mars — it will all drain right into that canyon.
That canyon could be the key to colonization — the lower down, the denser the atmosphere; roofing it over isn’t beyond our technical capabilities right now; cover it, add an Earthlike atmosphere mined in space; add some water. 100s of 1000s could live there fairly soon, for the generations it would take to introduce the same atmosphere from the same sources via bombardment in unoccupied areas.