Meanders in the Grand Canyon were formed over thousands of years. Water moves differently on the insides and outsides, pushing silt to the sides and you end up with a meander.
You can google it.
I find it particularly odd that, instead of showing the evidence, you merely claim it's there and tell him to go look. Typically, you're more than willing to post whatever you think supports your idea as a link, whether it be from the usual claptrap sites (AiG or Evolutionnews, et cetera) or something cherry picked from an authentic site on the matter. That you haven't done so, here, is very telling.
At any rate, where is this 'thousands' of years coming from? If I recall correctly, the Bible says the waters receded within a years time, more or less, so it seems odd that you're adding to it all the sudden. Why were there flood waters so persistent in this particular area?
Also, you may not be aware of this, but we actually know what happens to an area when flood waters ravage it for a great deal of time.
Channeled Scablands - Wikipedia, the free encyclopedia
The Channeled Scablands of Washington are area that experienced pretty much what you're suggesting here - thousands of years ago, there was0 a series of extremely powerful floods swept around the area for extended periods of time, called the Missoula Floods.
That's an area view. Compare that with the Grand Canyon.
You'll note that the former is more jagged, random, sporadic, completely lacking in the slow meanders that the latter picture exhibits - one long, winding path. It's a completely different structure. But it gets worse.
The Scablands have a variety of neat, unique geologic features; it's actually quite interesting. For instance, we have the presence of erratics, which are basically rocks, rather large ones, that are carried far from their sources and deposited in areas with different composition. We find these in the Scablands. We don't find them in the Grand Canyon.
We also find ripple marks, like these.
Also not present in the Grand Canyon.
Anyway, that's what I got after some Googling. What'd you get?