Could or could not G-d have created a fully formed, fully functional universe when only then began to operate along the lines of the "natural law" you believe in?
He could have. But He didn't.
And you know this how? Because you choose to believe it?
Could or could not the laws of nature as they existed prior to the sin, the flood, and the dispersion have been very, very different from the natural laws we know today?
I have no reason to believe so.
So you utterly reject all ancient tradition that conflicts with "modern science?"
I said I do not believe God would create human beings and give them a position in the universe perfectly situated as to discover the universal laws of physics, just to play games with them, when in fact He had actually created a universe that operates under completely separate principles.
So that's why you believe the "laws of nature" have been exactly as they are now from the very first fiat lux. It would be "unfair" for you scientists if they had ever been different at any time. So I guess this means you reject the idea that Adam and Eve were originally immortal as well. Why you think G-d should have greater respect for uniformitarian physical scientists than theologians is something you have chosen not to share.
That's not the God I know intimately through prayer and study of the sacred scripture and tradition.
What "tradition?" The perennial Tradition we have had since the days of Adam (for your sake I'll say Moses), or the measly "tradition" of Charles Darwin and Julius Wellhausen? Which of your church fathers taught "higher criticism?" St. Jerome, perhaps?
He did create it [the Grand Canyon]. He just decided to do so in a way that can be measured in terms of billions of revolutions of the earth around the sun. We call these "years."
And again, you know this how, since whether it was created in situ or as you describe it would look exactly the same? Are you saying it all comes down to personal preference as to what one chooses to believe?
Why are you so certain that after an initial instant of creation everything began to function naturally?
Mountains of empirical evidence in physics.
What "mountains of evidence?" As I said, whether the universe was created the way you or I believe it would still look and function exactly as it does. One way the laws of physics as we know them go all the back to fiat lux, the other they go all the way back to a time when they were changed from a previous state, and before that to a time when they began to function on a fully-assembled universe. You are basically admitting that you believe what you do merely because that is what you prefer to believe--again, because "G-d wouldn't lie to scientists" even though you believe he "lied" to theologians and scholars for three thousand years!
What makes you so certain it didn't?
I don't suppose your mind is the slightest bit open to the direct Divine authorship of the Torah, as in "written by G-d Himself and then dictated to Moses letter-for-letter at Mt. Sinai?" Do you have any grounds for your fanatical embrace of the "documentary hypothesis" other than that is what you enjoy believing?