Four modes of sediment transport are:

Here is 5

Dissolved Load - elements dissolved in solution

Suspended Load - very fine grained sediment such as clay and silt carried in suspension. The size grains that can be carried in suspension are dependent on the current velocity

Wash Load - a subset of the suspension load, extremely small particles (clay) that will remain in suspension independent of turbulence in the river

Saltation Load - particles that are temporarily carried in suspension but move by bouncing along the bottom
 
Bed Load - sediment that moves by rolling or sliding along the bottom. These are generally the coarser grained sediments such as sand and gravel.

Outermost (valence) electrons