But the scablands are too easily explained away as caused by a less than worldwide flood and they don't have any of the interesting features of the Grand Canyon.
I think you are missing the point of the scablands.
They are evidence of a series of meltwater floods that swept the area at the end of the last glacial period. The dates are in excess of 12,000 years.
Now here's the problem: we have good evidence of the timing and extent of these late glacial floods in eastern Washington
but we have no such evidence of a worldwide flood only about a third as old.
Hmmmm.
Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.
Belief gets in the way of learning--Robert A. Heinlein