Sand Waves and Crossed Currents in Rivers
How the fastest water shapes undulating sand-waves, and how an upper current ab crosses a lower current cd
The page treats the undulating 'scales' or waves that sand forms on a river bed. Leonardo observes that the fastest water most consumes the bottom of rivers, and that the sand-waves can shift together according to the river's direction, appearing much as waves do on the surface of water. A second diagram shows how water may flow along one line above and along a transverse line below, as demonstrated by ab and cd.
On this page
The fastest water consumes the river bed
The fastest water is that which most consumes the bottoms of rivers; from this arises the undulating manner, or 'scales', that the sand takes on, since the sand moved by the greatest course of water is cleared away the most.
Undulating sand-waves shift with the river
These waves of sand can change together according to the direction of the river, taking on a scaled or undulating form like that seen on the surface of the water.
Crossed currents: ab above, cd below
Water can flow along one line above and along another, transverse line below, as is demonstrated by ab and cd.