The material deposited by a river is called sediment. The bits of organic debris such as leaves and stems is detritus. Sediment includes detritus, inorganic material such as pebbles, sand, clay and other rock bits.
alluvium
alluvium
the bank of a river
I would call it a sediment.
sand bars
because of the black sediment left after fllods
sediment
Sediment
You call the bits of soil sediment.
Much of the coarser sediment material supplied by rivers settles out near shorelines or on beaches.
loess
The abrasion and attrition combined with hydraulic action on the river bed and the river banks erode away the underlying rock which results in small grains of rock we call sand. Depending on the speed of the river and the size of the particles, the sand will be deposited by the river at different stages (usually though it is found near the mouth of the river).
sediment
It is called the Fertile Cresent because it is in the shape of a cresent, and it has fertile, or rich, soil that is very good for farming.