Nothing here happens at once.
Each storm moves a film of sand no thicker than a fingernail. Run that arithmetic across ten thousand cloudbursts and the plateau loses a wall. The model carries the same bookkeeping the desert does: pick up on the steep, set down on the flat.
The deepest channel wins.
Whichever gully cuts fastest lowers its neighbours' outlet and captures their flow. Watch the map long enough and you'll see a tributary go dry as a rival beheads its headwaters — the same piracy that built every drainage on Earth.
A wash is a ledger of storms.
The braided sand on the canyon floor is every flood that ever passed, sorted and re-sorted. The terraces stepping down the walls are old floors, abandoned as the cut went deeper. Read them like tree rings turned on their side.
You are watching a hundred thousand years fall through a few minutes. The rock does not hurry, and it is never late.