River Transport: Heaviest Rocks Load Type

Rivers transport material (called the river load) in different ways depending on the size and weight of the particles and the energy of the water flow.

Types of River Loads

• Suspension Load: Very fine, lightweight materials (like silt and clay) are carried within the water column itself, appearing to float.
• Saltation Load: Small to medium-sized particles (like pebbles) bounce or skip along the river bed. They are lifted by the water and then fall back down.
• Traction Load: This load consists of the heaviest materials, such as boulders, cobbles, and larger rocks. These heavy materials are rolled, dragged, or pushed along the river bed by the force of the water.

Identifying the Load Type

The question specifically asks about the "heaviest rocks" that are "rolled along the river bed". This description directly matches the definition of the traction load. These are the coarsest sediments that require significant river energy to move, and they travel by rolling or sliding along the bottom.

Therefore, the heaviest rocks rolled along the river bed come under the traction load.