- 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
- Energy: Radioactive decay → Thermal energy
2. Exogenetic Forces (Earth Movements)
- Process → Denudation
- Forces that act and transform Earth's surface
- Land degradation forces
- Abrasion, breaking, levelling of Earth's surface
- Agents: Flowing water, wind, ocean waves, underground water, etc.
- Primary source of energy → Sun
⚠ Exam Trap
Himalayas → Endogenetic forces dominate, so height keeps
increasing; Aravallis → Exogenetic forces dominate, so height keeps
decreasing — frequently flipped in MCQs.
- Epeirogenic movement → Continent forming
- Orogenic movement → Mountain building → involves Tension and Compression
- Destructive results
- Earthquake, Volcano, Landslide
- Active horizontally and vertically (Slow motion)
- Uplift and extrusion activities (formation of landforms)
- 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)
- Erosion Cycle / Geographical Cycle: Proposed by William Morris Davis, later critiqued and modified by Walter Penck
- Result of erosion
- Accumulation of sediments / Aggradation
⚡ Quick Recall
Erosion → Geographical Cycle theory:
Davis (original) vs
Penck (critique/modification)
| 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
Mass Movements are driven purely by
Gravity — no transporting agent like wind/water is involved, unlike Erosion.
| Process | Key Feature | Agent / Energy |
|---|
| Endogenetic Forces | Internal, land formation, surface irregularities | Radioactive decay → Thermal energy |
| Exogenetic Forces | External, denudation, land degradation | Sun → Primary energy source |
| 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)