Saltation – Particles bouncing along the river bed (bouncing is the important word)
Too much salt was killing the nation (saltation), so the government ordered all salt pots to be bounced into the river.
In saltation, small rocks or pebbles which are too big to be carried wholly within the water are bounced along the bottom of the river bed by the force of the flow or current.
Saltation happens usually near the river's source, where the water is flowing faster and so has more force. Once rivers reach lower ground, they generally have insufficient force to move larger particles.