I also think this is in the realm of possibility. Who's to say god is not a single cell organism with higher brain activity and no sense of time as we see/feel it today? (or something like that). No less credible than "!POOF!" let there be light...
Back to the canyon question; One thing that convinces me that it was formed over a great period of time is the different wear patterns on the sides of the canyons. Some parts could have been gouged in a short period of time and some show patterns of wear and re-filling, then wear again. Hey maybe some of it could be receding water and some could be glacial.