Previous Year Question

Changes on the Earth’s surface are produced by both internal and external forces and processes. Each of the given factors contributes directly or indirectly to these changes.

1. Electromagnetic radiation: Solar energy powers the climate and hydrological systems. It drives thermal weathering and erosion and deposition by winds, rainfall, rivers, glaciers and sea waves.

2. Geothermal energy: Heat from the Earth’s interior provides energy for mantle convection, volcanism and tectonic activity. It is an important energy source for endogenic processes.

3. Gravitational force: Landslides, rockfalls, soil creep and the downslope movement of glaciers occur under gravity. Gravity also enables rivers to transport water and sediments from higher to lower elevations.

4. Plate movements: Plate motion produces mountains, folds, faults, rift valleys, earthquakes and volcanoes, causing major structural changes on the Earth’s surface.

5. Rotation of the Earth: Rotation produces the day-night cycle and the Coriolis force. The Coriolis force influences winds, ocean currents and the direction of flowing water.

6. Revolution of the Earth: Revolution, together with axial tilt, produces seasons. Seasonal changes in temperature, precipitation, winds, river discharge and glaciers influence geomorphic processes.

Therefore, all six factors contribute to dynamic changes on the Earth’s surface.