Endogenic and exogenic forces

Climate and rock nature control weathering and erosion. In exams, use these factors for regional variation.

A deep narrow valley forms by vertical river erosion on a steep gradient. In exams, infer the process from valley shape.

Crustal uplift is an endogenic process linked with internal energy. In exams, do not classify uplift as exogenic.

Rejuvenation can make a river incise again. In exams, connect new valleys on old surfaces with rejuvenation.

The direct answer is C, exogenic because an external agent erodes the surface. Sea waves are water movements acting at the coast, outside the Earth’s interior. They strike cliffs and beaches, loosen particles, carry them away, and reshape the shoreline. Step by step: wave energy reaches the coast; repeated impact and pressure crack or weaken coastal rock; loosened material is removed or transported; the coast is worn back. Option A is wrong because coastal waves are not driven by magma; magma is molten material inside Earth. Option B is wrong because ordinary wave erosion does not mean that waves fold the crust; folding is a tectonic, internal process. Option C is correct because it identifies both the external agent and the surface erosion. Option D is wrong because a sea wave is not the same thing as an earthquake; although earthquakes can sometimes generate special waves such as tsunamis, ordinary coastal erosion by waves is classified by the active agent here, namely seawater. Memory cue: water, wind, ice, and waves acting on the surface are exogenic agents.

When energy decreases, an agent deposits material. In exams, link deposition with lower velocity or carrying capacity.

Exogenic forces cut, modify and deposit on existing relief. In exams, connect relief change with three processes.

Answer: D. Endogenic processes arise from forces within the Earth and do not have just one speed. Some act slowly over very long periods: folding, broad uplift, subsidence, and gradual plate movement can build or reshape major landforms. Other endogenic events release stored stress suddenly, as in earthquakes, and may change the ground in a short time. D is correct because it includes both slow crustal movements and sudden earthquakes. A is too narrow because not all endogenic processes are sudden. B is also too narrow because earthquakes can occur abruptly, even though their accumulated stresses may develop over long periods. C is false because endogenic forces help create mountains, plateaus, faults, volcanoes, and other landforms. Memory cue: internal forces can be slow builders or sudden shakers.

Warm humid conditions speed up chemical reactions. In exams, link chemical weathering with moisture and temperature.

Freezing and thawing physically break rocks. In exams, link temperature changes with mechanical weathering.

Exogenic processes do not only erode, they also create landforms by deposition. In exams, remember both erosion and deposition.

Endogenic processes can create major relief and new landforms. In exams, link mountains and volcanoes with endogenic construction.

Climate changes the rate and type of exogenic processes. In exams, understand climate effects on similar rocks.

Rock first breaks down, then material is removed, transported and deposited. In exams, this sequence helps for exogenic cycle questions.

Uplift can increase gradient and river cutting power. In exams, link uplift with river rejuvenation.

Gradation is the tendency to balance or level the surface. In exams, link it with combined erosion and deposition.

A glacier can carry material as an external agent. In exams, link transport with exogenic agents.

Endogenic forces build relief and exogenic forces modify it. In exams, express the contrast clearly.

Joints allow water entry and increase rock breakdown. In exams, remember structure as a control of weathering.

Ash comes from a volcanic source and rainfall erodes it exogenically. In exams, distinguish source from later action.

Long-term exogenic erosion can create low-relief surfaces. In exams, connect level surfaces with long-term gradation.

Seismic uplift creates slopes, and gravity can cause landslides. In exams, connect endogenic cause with exogenic result.

An earthquake may be sudden, while weathering and erosion act over long periods. In exams, connect process speed with examples.

Weathering supplies broken material that agents can remove. In exams, view weathering as preparation for erosion.

Landforms evolve through continuous interaction of both processes. In exams, write construction and reshaping together.