Thanks for the link. I think that would prove my point though. Age is already there in the rock formation. The river had nothing to do with the age of the Canyon.
Now the part that 270mya the river existed at the top before any depth prior to a Canyon. The first assumption would be did none of the Canyon exist even before a sea was formed. There could have still been a river prior to the sea, and even a Canyon unless you can prove the sea itself happened more than 270mya. Is there proof that the sea put down a billion years worth of material?
My theory. There was already a Canyon in place however the size does not matter. After the Flood came the sea or even multiple seas for that matter. The sea/s helped form the Canyon even more. There does not have to be any specific timetable for when or even how the sea or seas came and went. Since this is not dogma nor doctrine, then figuring out an exact time frame is not right or wrong. We know that flooding and the formation of seas do not need long periods of time. I know that using dating methods and all the new satalite imaging of all types may give us evidence of a tighter time frame. But if we agree there were seas, I think that we would also have to acknowledge flooding as factoring into how the Canyon was formed and not just a river without any flooding at all.