Correct Option
The correct option is 1 and 3 only.
Explanation
Mass movements refer to the transfer of rock debris, soil, or mud down a slope primarily under the influence of gravity. These movements are a part of exogenic geomorphic processes but are distinct from erosion, as they do not rely on transporting media like flowing water or wind to carry the material.
Statement-wise Analysis
- Statement 1 is Correct: Mass movements involve the detachment and downslope transport of soil and rock material. The driving force behind this process is the direct influence of gravity. The material moves under its own weight, without the aid of other transporting agents.
- Statement 2 is Incorrect: In mass movements, gravity is the sole driving force. While running water, glaciers, wind, and waves are geomorphic agents responsible for erosion and transport, they do not participate directly as carrier agents in mass movements. Although water may aid the process by lubricating the slope or adding weight to the material, it is not the primary agent moving the debris.
- Statement 3 is Correct: Weathering breaks down rocks and reduces their cohesion, making them more susceptible to gravity. Consequently, mass movements are much more active over weathered slopes compared to unweathered materials, which retain higher structural integrity and resistance to movement.
Key Takeaway
Mass movements are driven exclusively by gravity and do not require geomorphic agents like wind or running water for the transport of material, distinguishing them from erosion.