Methods of Transportation

At all times, the river is either eroding sediment, or depositing sediment, and this is dependent on the amount of energy that the river has. Of course, this material is often moved by the river, and the river does this using one of four different methods, dependent on the particle size.

First is traction. Traction involves larger particles such as boulders being rolled along the bottom of the riverbed. You can imagine how heavy larger bedrock is, and therefore this method is most common when the river has a lot of energy, such as when the river is in flood.

Second is saltation. Saltation is similar to traction, but this process involves the movement of smaller particles, often pebble sized, that are bounced along the riverbed, rather than rolled, due to them being lighter in weight.

Third is suspension. Suspension involves very small particles like silt and clay being carried along and suspended within the water. These particles are much lighter, and therefore the river has enough energy to pick up, and carry these particles along. This process makes a river often look dirty in appearance.

Finally, you have solution. Solution describes the process of rock particles such as limestone or chalk, being dissolved by the river water, and therefore we cannot see this process with the naked eye, due to the rock particles being so small after being subjected to the dissolving process.

So, to conclude, we have traction, saltation, suspension and solution, and the main way to distinguish between them is down to particle size, with the size becoming smaller as you move through the processes in the order just discussed.