Weathering, mass wasting, erosion and transportation are indicators of which one of the following processes?
- (a)Denudation
- (b)Endogenetic process
- (c)Diastrophism
- (d)Mountain building
Correct — A, Denudation. Denudation is the umbrella term for the exogenic (external, land-wearing) processes that strip and lower the Earth's surface, and its four members are exactly weathering, mass wasting, erosion and transportation. Weathering breaks rock in place, mass wasting slides the loosened debris downslope under gravity, erosion detaches and lifts material, and transportation carries it away. All four act to reduce relief, so the group named in the question is denudation.
- (b)Endogenetic process — Endogenetic (internal) processes are powered by the Earth's internal heat and build up or deform the crust (vulcanicity, tectonics) — the opposite of the surface-wearing, exogenic set listed here.
- (c)Diastrophism — Diastrophism is the deformation of the crust by folding, faulting and warping — an internal, crust-building process, not the wearing-down family of weathering and erosion.
- (d)Mountain building — Mountain building (orogeny) raises relief through tectonic uplift; it is a constructive endogenic process, whereas weathering, erosion and transport act to lower that relief.
Denudation is the sum of the exogenic gradational processes that wear the land down — weathering, mass wasting, erosion and transportation. It is opposed to endogenic processes (diastrophism, vulcanicity and orogeny), which are driven by the Earth's internal heat and build relief up. The land surface is shaped by the tug-of-war between these building-up and wearing-down forces.
All four options sound like major Earth processes, which is the trap. The tell is the direction of action: every sub-process named in the stem removes or lowers material, so the correct umbrella term must be the wearing-down one — denudation — while the other three options are all internal, relief-building processes.
- Denudation = weathering + mass wasting + erosion + transportation, the exogenic processes that lower the land.
- Weathering breaks rock in situ and must precede erosion, which removes the loosened material.
- Endogenic processes (diastrophism, vulcanicity, orogeny) build relief; exogenic processes reduce it.
- The chief agents of erosion and transport are running water, glaciers, wind and waves.
- Weathering — rock is broken down in place (physical, chemical, biological)
- Mass wasting — loosened debris moves downslope under gravity
- Erosion — agents (water, ice, wind, waves) detach and pick up material
- Transportation — the material is carried away, lowering the land
These four exogenic sub-processes together make up denudation — option (a).
- Confusing denudation (wearing down) with diastrophism or orogeny (building up).
- Treating weathering and erosion as the same thing — weathering breaks rock in place, erosion removes it.
As a one-line 'which process do these terms indicate' item testing the exogenic vs endogenic distinction.
Statement-I: Rainfall is one of the reasons for weathering of rocks. Statement-II: Rain water contains carbon dioxide in solution. Statement-III: Rain water contains atmospheric oxygen. Which one of the following is correct in respect of the above statements?
- (a) Both Statement-II and Statement-III are correct and both of them explain Statement-I
- (b) Both Statement-II and Statement-III are correct, but only one of them explains Statement-I
- (c) Only one of the Statements II and III is correct and that explains Statement-I
- (d) Neither Statement-II nor Statement-III is correct
Answer(a) Both II and III are correct and both explain I — carbonation and oxidation are chemical weathering.
Zooms into weathering — the first stage of denudation — showing how rain drives chemical weathering, exactly the exogenic wearing-down family this NDA item names.
Which of the following is/are the applied forces in mechanical weathering process? 1. Gravitational force; 2. Expansion force; 3. Force due to water pressure.
- (a) 1 only
- (b) 1 and 2 only
- (c) 2 and 3 only
- (d) 1, 2 and 3
Answer(d) 1, 2 and 3
A later NDA paper drilling into weathering, the leading component of denudation — reinforces the same exogenic-process theme.
- practice — not a real PYQ
Which one of the following is an endogenic (internal) process?
- (a)Weathering
- (b)Erosion
- (c)Diastrophism
- (d)Mass wasting
Answer(c) Diastrophism — the folding and faulting of the crust is internal, unlike the exogenic wearing-down processes.
- practice — not a real PYQ
The breaking down of rocks in their place of origin, without any movement of the broken material, is called
- (a)erosion
- (b)weathering
- (c)transportation
- (d)deposition
Answer(b) weathering — it acts in situ and precedes erosion, which removes the debris.