- Changes in surface configuration
- Effects of endogenetic and exogenetic forces
1. Endogenetic Forces (Earth Movements)
- Generated from internal part of the Earth
- Creation of surface irregularities
- Forces responsible for land formation
- Internal energy: radioactive decay plus residual/primordial heat
2. Exogenetic Forces (Earth Movements)
- Process → Denudation
- Forces that act and transform Earth's surface
- Denudation, transport and deposition; external processes can also build landforms.
- Abrasion, breaking, levelling of Earth's surface
- Agents: Flowing water, wind, ocean waves, underground water, etc.
- External energy: mainly solar energy plus gravity
⚠ Exam Trap
Himalaya: active convergence/uplift competes with strong erosion;
Aravalli: ancient, deeply denuded mountain system with much weaker active uplift.
- Epeirogenic movement → Continent forming
- Orogeny: mountain-building deformation, especially compression, folding and thrust faulting
- Destructive results
- Sudden tectonic/volcanic events: earthquakes and eruptions; landslides are gravity-driven mass movement.
- Active horizontally and vertically (Slow motion)
- Uplift, subsidence, folding and faulting
- Helpful in the formation of mountains
⚡ Quick Recall
Epeirogenic → broad continent-level movement · Orogenic → focused mountain-building movement
Diastrophism
- Epeirogenic (Continent forming)
- Orogenic (Mountain building) → Tension, Compression
Weathering
- Physical
- Chemical
- Biological
Erosion
- Sea
- Rivers / Water
- Ice
- Wind
- Underground water
⚡ Quick Recall
Diastrophism & Sudden Movements → Endogenetic in origin · Weathering & Erosion → Exogenetic in origin
- Disintegration of rocks at their place / decay of rocks
- Exfoliation: Mechanical weathering process / Separation of rock layers beneath curved plates
Physical Weathering
Caused by temperature change, frost, pressure relief
Chemical Weathering
Oxidation, Carbonation, Hydration, Hydrolysis, Solution
Biological Weathering
By plants, animals, microorganisms breaking rocks
⚠ Exam Trap
Weathering happens
in-situ (no transport of material); Erosion involves
actual transport of disintegrated material — this distinction is a classic exam trap.
- Transfer of disintegrated rock material to another place by external agents
- Agents: Wind, Ice, Water, etc. (Work of rivers during different stages)
- William Morris Davis: staged geographical cycle; Walther Penck: alternative uplift–denudation/slope-development model.
- Result of erosion
- Accumulation of sediments / Aggradation
⚡ Quick Recall
Davis: classic staged geographical cycle;
Walther Penck: alternative model linking uplift, denudation and slope evolution.
| Key Point | Details |
|---|
| Definition | Movement of rock debris downslope |
| Effect / Driving Force | Gravitational Force |
| Types | 1. Slow movement • 2. Rapid movement |
| Processes / Effects | Landslides, Avalanche, Earth flow, Solifluction, etc. |
⚡ Quick Recall
Gravity is the primary mass-movement driver; wind/flowing water is not required as the main transporting agent, but
water can trigger or mobilize flows.
| Process | Key Feature | Agent / Energy |
|---|
| Endogenetic Forces | Internal, land formation, surface irregularities | Radioactive decay + residual/primordial internal heat |
| Exogenetic Forces | External, denudation, land degradation | Mainly solar energy + gravity |
| Weathering | In-Situ (no transport), disintegration | Physical / Chemical / Biological |
| Erosion | Transport of disintegrated material | Wind, Ice, Water, Rivers |
| Deposition | Result of erosion, sediment accumulation | All erosion agents |
| Mass Movement | Rock debris downslope | Gravitational Force |
⚡ Quick Recall
Sequence: Weathering (breaks rock in place) → Erosion (transports it) → Deposition (settles it elsewhere)