The correct option is 2 and 3 only.
Explanation
Gravity is a directional force that activates all exogenic geomorphic processes. It acts as the primary driving force behind the movement of materials on the Earth's surface by converting potential energy into kinetic energy.
Statement-wise Analysis:
- Statement 1 is Incorrect: Gravity is the force that pulls all matter towards the center of the Earth. On any sloping surface, gravity resolves into components that drive materials downward. Therefore, gravity facilitates and drives downslope movements (such as mass wasting and flow of water) rather than preventing them.
- Statement 2 is Correct: Gravity applies a force on all matter, creating gravitational stress. This stress acts on Earth's materials, causing deformation and movement. It creates shear stress which attempts to separate and move the material downslope.
- Statement 3 is Correct: Erosion and transportation require kinetic energy to move materials. This energy is derived from the potential energy provided by gravity. Similarly, deposition occurs when materials settle due to gravity once the transport medium loses energy. Without gravity and gradients (slope differences), agents like running water, glaciers, or wind would not move, making erosion and deposition impossible.
Key Takeaway:
Gravity is the fundamental force that activates exogenic processes. It creates the stress required for the breakdown of rocks and provides the energy necessary for the transportation and deposition of earth materials.