Endogenic and exogenic forces

Earthquakes and volcanism are linked with energy from inside the Earth. For exams treat them as major examples of endogenic processes.

Exogenic forces erode high areas and deposit material in lower areas. For exams remember them as leveling forces.

Direct answer: Option B, weathering. Weathering is the breaking down or chemical alteration of rock at the place where the rock lies. It does not require the broken material to be carried away. Option A, erosion, is different because it includes removal and transport by water, wind, ice or waves; weathering may come before it. Option B is correct because the phrase “at its original place” is the defining clue. Option C, deposition, means material is laid down after transport, so it is the opposite stage of movement. Option D, diastrophism, means large-scale deformation or movement of Earth’s crust, such as folding and faulting, not ordinary breaking of exposed rock. A simple chain is: rock breaks in place = weathering; material moves = erosion; material settles = deposition. Memory cue: weathering stays, erosion carries.

In erosion broken material is removed and carried by water wind ice or waves. For exams remember both removal and transport.

Diastrophism causes folding faulting uplift or subsidence in the crust. For exams treat it as an endogenic process.

Orogenic movement is related to mountain building. For exams connect orogeny with formation of mountain belts.

Epeirogenic movement is linked with slow vertical changes on a continental scale. For exams remember it as broad uplift and subsidence.

In a landslide rock and soil move downslope due to gravity. For exams treat it as rapid mass movement.

In the upper course a steep gradient makes the river cut downward strongly. For exams connect youthful rivers with vertical erosion.

Waves cut and abrade coastal rocks. For exams treat coastal cutting as an example of exogenic erosion.

When energy decreases rivers wind or glaciers start depositing their load. For exams connect deposition with a fall in energy.

Temperature variation causes expansion and contraction of rocks and can break them. In exams it may also be called mechanical weathering.

In warm humid conditions water and heat speed chemical reactions. For exams consider moisture important for chemical weathering.

Karst landforms develop due to chemical solution of limestone. For exams connect karst with the solution process.

A lava plateau forms when large lava flows solidify. For exams treat it as a volcanic endogenic landform.

The direct answer is A, lowering of the land surface by erosion. In geomorphic gradation, degradation means the wearing down or lowering of higher land. Step by step: weathering breaks rock into smaller material; running water, wind, ice, or waves remove and transport that material; hills, slopes, or other high surfaces lose height; the land is lowered. Option A is correct because it gives the essential meaning of degradation: erosion cuts down the surface. Option B, deposition of sediments in low areas, is called aggradation, not degradation. Deposition builds or raises low places instead of lowering high places. Option C, folding of the crust from inside, is an endogenic tectonic movement and is not the meaning of geomorphic degradation. Option D, cooling of lava, is a volcanic process in which molten material solidifies; it may form rock, but it does not define the lowering of land by erosion. A useful contrast is: degradation removes material and lowers relief, while aggradation adds material and raises or fills low areas. Memory cue: “degrade” means cut down; “aggrade” means build up.

In aggradation deposition raises or fills the surface. For exams treat it as a depositing process.

Compression folds rock layers and can form fold mountains. For exams remember the Himalayas as a major example.

A fault involves fracture along with displacement in rocks. For exams remember not only fracture but also displacement.

An earthquake occurs due to sudden release of stored energy inside Earth. For exams treat it as a sudden endogenic process.

Water freezing in cracks expands and creates pressure that can break rock. For exams remember frost action as physical weathering.

Volcanism is driven by energy from inside the Earth. For exams place volcanoes in the endogenic category.

The direct answer is A: river erosion is performed by running water. An exogenic process works at the surface, and an agent is the natural force that performs it. Running water cuts, loosens and carries soil and rock, so it is the agent of river erosion. The process is erosion; the agent is flowing water. Option A correctly pairs them. Option B is wrong because diastrophism means large-scale crustal deformation caused by internal tectonic forces, not by running water; therefore it is endogenic, and the agent is mismatched. Option C is wrong because earthquakes result from sudden internal movement, not from wind. Option D is wrong because volcanism is caused by magma and internal heat, while a glacier is moving ice; these terms do not form a correct process-agent pair. The useful method is to ask two questions: what action is happening, and what force performs it? Here, “cutting river channels” is erosion and “flowing water” is the agent. Memory cue: running water erodes, transports and deposits; match the agent to the process it actually causes.

Magma pressure is related to internal Earth processes. For exams treat water wind ice and waves as external agents.

In plains lower gradient reduces river energy and sediments are deposited. For exams connect low velocity with deposition.