Endogenic and exogenic forces

Endogenic forces are driven by heat and pressure from within the Earth. For exams remember them as forces that uplift and deform the crust.

Exogenic processes are driven by solar-energy-based weather systems and gravity. In exams link weathering and erosion with exogenic processes.

Diastrophism is a large crustal change caused by internal forces. For exams connect folding and faulting with it.

Volcanism occurs when material and energy come from inside the Earth. Therefore it is an example of an endogenic force.

In weathering rocks break down or chemically change in place. For exams remember that transport separates erosion from weathering.

In erosion broken material is removed and transported by water wind ice or waves. For exams treat transport as the key sign of erosion.

Denudation is a collective term for exogenic processes that lower elevated land. It includes weathering erosion and mass movement.

Degradation cuts down the land while aggradation deposits material. For exams understand both as exogenic balancing processes.

Endogenic forces create relief like mountains and plateaus while exogenic forces cut or fill them. For exams remember this creation and modification contrast.

Direct answer: Option A, sudden endogenic process. An earthquake is a rapid shaking of the ground caused by the sudden release of energy inside Earth. Usually, stress builds up in rocks and is released when they slip along a fault. Because the source is internal, the process is endogenic; because the energy is released quickly, it is sudden rather than slow. Option A is correct for both reasons. Option B is wrong twice: an earthquake is not exogenic, and it is not a slow process. Option C is wrong because biological deposition involves organisms building or accumulating material, not fault energy. Option D is wrong because chemical weathering is a gradual surface process in which minerals react with water, gases, or acids. Some earthquakes can trigger landslides or alter rivers, but those effects do not change the earthquake’s primary classification. Memory cue: sudden energy released inside Earth equals sudden endogenic process.

Mountain building takes place over a long time through diastrophism. For exams connect it with orogenic activity.

Fold mountains form when rock layers bend under compression. For exams remember the Himalayas as an example of fold mountains.

In faulting rock layers fracture and displacement occurs on either side. For exams treat faulting as a result of diastrophism.

Epeirogenic movement involves slow uplift or subsidence over large areas. For exams connect it with continental-scale changes.

Orogenic movement produces mountain belts. For exams remember orogeny as the process of mountain building.

In mass movement gravity pulls rock or soil downslope. For exams consider it a part of exogenic processes.

Direct answer: A is correct. A river flows over the land surface. Moving water applies force to soil and rock, loosens particles, and carries them downstream. The wearing away of material is erosion, while the movement of the loosened material is transportation. Because the river acts at or near the surface and is powered by external agents such as running water and gravity, the process is exogenic. Option A correctly combines both ideas: an external process and erosion. Option B is wrong because volcanic activity comes from internal heat and magma, not from a river cutting a valley. Option C is wrong because seismic processes concern earthquakes and ground vibrations; a river may use cracks but is not itself a seismic process. Option D is wrong because ordinary river valley cutting removes and transports material rather than forming new crust. Memory cue: running water cuts, carries and sometimes deposits; these are exogenic actions.

Moving glaciers scrape and cut rocks. For exams remember glaciers as agents of exogenic erosion.

In warm and humid climates water and heat speed up chemical reactions. For exams treat such climate as favorable for chemical weathering.

Temperature changes and freeze-thaw action physically break rocks. For exams connect dry and cold regions with mechanical weathering.

An increased gradient can raise a river's energy and erosive capacity. For exams understand the link between endogenic uplift and exogenic erosion.

A lava plateau forms by the solidification of extensive lava flows. Therefore its basic cause is volcanic endogenic activity.

Long-term erosion removes weaker parts and leaves resistant parts behind. For exams connect residual landforms with selective erosion.

Exogenic forces level land by eroding high areas and depositing material in low areas. For exams treat them as balancing forces.

The direct answer is A, formation of a river delta. A delta is a deposit of sediment near a river’s mouth, where the river enters a sea, lake, or slower water. Step by step: the river erodes material upstream; it carries sand, silt, and clay downstream; the current loses speed at the mouth; the transported material settles; repeated deposition builds a delta. This is exogenic because the agent, flowing water, works on the surface. Option A is correct because a delta is directly formed by river deposition. Option B, folding of the crust, results mainly from internal tectonic pressure and is endogenic. Option C, formation of an earthquake focus, concerns the underground point where an earthquake begins, so it is linked with internal tectonic activity, not surface deposition. Option D, upward movement of magma, involves material and energy inside Earth and is endogenic or volcanic, not exogenic. A delta is not formed simply because a river exists; deposition must occur where flow slows and sediment accumulates. Exam cue: river plus deposited sediment at its mouth equals delta and exogenic deposition.