UPSC Prelims 2013 · Question 68 of 99
UPSC Prelims 2013 question on Forces Shaping Earths Surface
- ExamUPSC CSE
- Year2013
- PaperGeneral Studies Paper I
- SubjectGeography
- TopicGeomorphology
- DifficultyHard
- TypeStatement
Consider the following:
1. Electromagnetic radiation
2. Geothermal energy
3. Gravitational force
4. Plate movements
5. Rotation of the Earth
6. Revolution of the Earth
Which of the above are responsible for bringing dynamic changes on the surface of the Earth?
Show answer
Answer: D. 1, 2, 3, 4, 5 and 6
Verdict
Correct Answer: 1, 2, 3, 4, 5 and 6
Analysis
According to the official UPSC Answer Key for Prelims 2013 General Studies Paper, the correct option is 1, 2, 3, 4, 5 and 6.
Earth’s surface is continuously modified by both internal forces and external forces. These include solar energy, internal heat, gravity, plate movements, rotation and revolution.
Statement by statement
1. Electromagnetic radiation — Correct
Solar radiation is the main external source of energy for Earth’s surface processes.
It drives climate, winds, rainfall, evaporation and the water cycle.
These processes cause weathering, erosion and deposition.
2. Geothermal energy — Correct
Geothermal energy comes from Earth’s interior.
It drives mantle convection, volcanism and tectonic activity.
These internal processes create and modify major landforms.
3. Gravitational force — Correct
Gravity controls the downslope movement of materials.
It causes mass wasting processes such as landslides, rockfalls and avalanches.
It also influences river flow and sediment movement.
4. Plate movements — Correct
Plate movements reshape Earth’s surface through folding, faulting, earthquakes and volcanism.
They are responsible for mountain building, rift valleys and ocean basins.
This is a major endogenic force.
5. Rotation of the Earth — Correct
Earth’s rotation causes the Coriolis effect.
This affects the direction of winds and ocean currents.
It also contributes to the day-night cycle, which influences temperature-related weathering.
6. Revolution of the Earth — Correct
Earth’s revolution around the Sun, along with axial tilt, causes seasons.
Seasonal changes influence rainfall, glaciers, vegetation and weathering processes.
Thus, it indirectly affects Earth’s surface changes.
Extra UPSC info
* Endogenic processes originate inside the Earth, such as volcanism, earthquakes, folding and faulting.
* Exogenic processes operate on the Earth’s surface, such as weathering, erosion, transportation and deposition.
* Solar energy and gravity are the main drivers of exogenic processes.
* Geothermal energy is mainly responsible for endogenic processes.
* Aggradation means building up of landforms through deposition.
* Degradation means wearing down of landforms through erosion and weathering.
How to crack it
All six factors contribute directly or indirectly to changes on Earth’s surface, so the correct answer is 1, 2, 3, 4, 5 and 6.