CAPF AC 2021 Q103: Geography – Physical Geography & Geomorphology
The heaviest rocks, which are rolled along the river bed in river transport, come under which type of load?
- (a) Solution load
- (b) Suspension load
- (c) Saltation load
- (d) Traction load
Answer: (d) Traction load
Explanation
How a river carries its load
How to think: a river moves material in four ways, sorted by size.
The heaviest pieces cannot be lifted, so they are dragged or rolled along the bed.
The word for dragging is traction.
| Type of load | Size of material | How it moves |
|---|---|---|
| Solution | Dissolved minerals | Carried invisibly in the water |
| Suspension | Fine silt and clay | Floats in the water, makes it muddy |
| Saltation | Sand and small pebbles | Hops and bounces along the bed |
| Traction | Boulders and large pebbles | Rolled or dragged along the bed |
Bed load: saltation and traction together are called the bed load.
Answer: (d) Traction load.
Why each option is right or wrong
- (a) Incorrect. The solution load is dissolved material, the lightest of all.
- (b) Incorrect. The suspension load is fine silt floating in the water.
- (c) Incorrect. In saltation smaller particles hop along the bed; they are not the heaviest.
- (d) CORRECT. The heaviest rocks are rolled along the bed as the traction load.
Key point
River transport: solution (dissolved), suspension (fine, floating), saltation (bouncing sand), traction (rolled boulders). Bed load = saltation + traction.
Remember
Traction = heaviest rocks rolled on the river bed.
Common mistakes
- Mixing up saltation (hopping) with traction (rolling).
- Thinking saltation has to do with salt dissolved in the water.
- Assuming the heaviest material travels in suspension during floods.
Exam tip
Educated guess: think of a tractor, which pulls heavy loads along the ground. Traction means pulling or dragging.
Sources
- NCERT Class XI Geography — Fundamentals of Physical Geography, Chapter 6: Geomorphic Processes (erosion and transportation)
- G. C. Leong, Certificate Physical and Human Geography — Running Water