What's faster, water erosion or the tectonic raising of the landscape? Answer: water erosion, always.
Say a pre-existing river cuts right across where a tectonic compression is raising a mountain ridge. The rising of the land dams the water a bit. You get a bit of a lake, with a natural spillway in the old riverbed where the water flows over the rising hump.
The downstream side of the hump wears away faster than the river bottom upstream or downstream. What happens? The "spillway" erodes back to the "lake" and it all gives out with a big rush.
You can see this sort of thing everywhere. In the Sweetwater Valley, which I visited to reseach a book, there's a spectacular cut through a ridge of bare rock.
Note that, if the ridge is there before the river forms, the river channel simply forms in such a way to go around the ridge and that's that.
The Grand Canyon is not a problem for mainstream science. It's a problem for all the psychoceramics who would like to explain it any other way.