The correct option is 1 and 2 only.
Explanation
Geomorphic processes are forces that shape the Earth's crust. They are broadly classified into Endogenic forces (internal origin) and Exogenic forces (external origin). The interaction between these forces results in the creation, modification, and destruction of landforms.
Statement-wise Analysis:
- Pair 1 is Correct: Orogeny is a mountain-building process. It involves tangential (horizontal) forces that cause severe folding, faulting, and thrusting of the Earth's crust, leading to the formation of fold mountains.
- Pair 2 is Correct: Epeirogeny is a continent-building process. It involves radial (vertical) forces that cause the uplift or subsidence of large landmasses without significant folding or deformation.
- Pair 3 is Incorrect: Exogenic forces (such as wind, water, and glaciers) derive energy from the sun and gravity. They act to wear down relief features through weathering and erosion. Therefore, they are land-wearing forces (denudational), not land-building forces.
- Pair 4 is Incorrect: Endogenic forces originate from within the Earth. They create surface irregularities by elevating or building up portions of the crust (via volcanism and diastrophism). Therefore, they are land-building forces, not land-wearing forces.
Key Takeaway:
Endogenic forces are constructive processes that build landforms (e.g., mountains, plateaus), whereas Exogenic forces are destructive processes that degrade or level the land surface.