In the Northern Hemisphere, the Coriolis force deflects moving objects to the right. Rivers feel this: flow curves rightward, pressing harder against the right bank. The standard result is that right banks erode faster — the Amazon, the Mississippi, many Northern Hemisphere rivers show asymmetric bank erosion consistent with Coriolis deflection.

Liu and Liu (arXiv:2603.16912) demonstrate that the Yellow River does the opposite. The right (south) bank accumulates sediment. Sand and pebbles pile up precisely where erosion theory predicts removal. The resolution is sediment concentration.

The Coriolis force acts on everything the water carries. In a clear river, the deflected current hits the right bank with erosive force and there is little sediment to deposit. In the Yellow River — historically the world’s most sediment-laden major river — the deflected current carries enormous quantities of suspended material. When the flow presses rightward, it pushes sediment rightward too. If the sediment load is heavy enough, deposition overwhelms erosion.

The switch point is a concentration threshold. Below it, Coriolis means erosion on the right bank. Above it, Coriolis means deposition on the right bank. The same force, the same direction, opposite geomorphological outcomes — determined entirely by what the water carries.

This is a phase inversion driven by a single parameter. The force doesn’t change sign; the response does. The river’s sediment concentration transforms the Coriolis effect from a destructive agent into a constructive one, and the mechanism is simply that sediment transport responds to the same deflection as water transport. The same physics that carves one riverbank builds another, separated only by the density of what the current holds.