Geomorphology is a branch of physical geography that studies the origin, evolution, structure, and classification of landforms on the Earth’s surface. The word “Geomorphology” is derived from three Greek words—Geo (Earth), Morphe (Form), and Logos (Study). It explains how various natural forces such as rivers, glaciers, wind, waves, and tectonic movements shape the Earth’s surface.
NDA & CDS 2 2026 Exam GK – Geography – Geomorphology
Earth’s Interior Structure
The Earth is divided into three major layers:
1. Crust
- Outermost solid layer of the Earth.
- Thickness ranges from 5 km beneath oceans to 70 km beneath continents.
- Composed mainly of silica and alumina (SIAL) on continents and silica and magnesium (SIMA) beneath oceans.
2. Mantle
- Extends up to about 2,900 km below the crust.
- Rich in magnesium and iron.
- Contains semi-molten materials that facilitate plate movement.
3. Core
- Innermost layer.
- Composed mainly of iron and nickel (NIFE).
- Divided into:
- Outer Core (liquid)
- Inner Core (solid)
Endogenic and Exogenic Forces
Endogenic Forces
These forces originate within the Earth.
Examples:
- Earthquakes
- Volcanic eruptions
- Folding
- Faulting
- Plate tectonic movements
They create major relief features such as mountains, plateaus, and rift valleys.
Exogenic Forces
These forces operate on the Earth’s surface.
Examples:
- Running water
- Wind
- Glaciers
- Sea waves
- Groundwater
They wear down elevated landforms through erosion and deposition.
Geological Processes
Weathering
Weathering refers to the breakdown of rocks in situ (without movement).
Types of Weathering
1. Physical Weathering
- Caused by temperature changes.
- Frost action and exfoliation are common examples.
2. Chemical Weathering
- Caused by chemical reactions.
- Includes oxidation, carbonation, hydration, and solution.
3. Biological Weathering
- Caused by plants, animals, and microorganisms.
Mass Wasting
Mass wasting is the downhill movement of weathered material under gravity.
Examples:
- Landslides
- Rockfalls
- Mudflows
- Soil creep
Major causes:
- Heavy rainfall
- Earthquakes
- Deforestation
- Human activities
Plate Tectonic Theory
The Plate Tectonic Theory explains the movement of lithospheric plates over the semi-fluid asthenosphere.
Major Tectonic Plates
- Pacific Plate
- Eurasian Plate
- Indo-Australian Plate
- North American Plate
- South American Plate
- African Plate
- Antarctic Plate
Types of Plate Boundaries
1. Divergent Boundary
- Plates move apart.
- New crust is formed.
- Example: Mid-Atlantic Ridge.
2. Convergent Boundary
- Plates move towards each other.
- Mountain building and volcanic activity occur.
- Example: Himalayas.
3. Transform Boundary
- Plates slide past each other.
- Earthquakes are common.
- Example: San Andreas Fault.
Continental Drift Theory
Proposed by Alfred Wegener in 1912.
Main Idea
- All continents were once joined together in a supercontinent called Pangaea.
- Pangaea later split into:
- Laurasia (Northern part)
- Gondwanaland (Southern part)
This theory later led to the development of Plate Tectonic Theory.
Mountain Formation
Mountains are formed through tectonic activities.
1. Fold Mountains
Formed by compression and folding of rock layers.
Examples:
- Himalayas
- Alps
- Andes
Young Fold Mountains
- Himalayas
- Rockies
- Andes
Old Fold Mountains
- Aravalli Range
- Appalachians
2. Block Mountains
Formed due to faulting.
Examples:
- Black Forest (Germany)
- Vosges Mountains (France)
3. Volcanic Mountains
Formed by volcanic eruptions.
Examples:
- Mount Fuji
- Mount Kilimanjaro
4. Residual Mountains
Formed by erosion of existing mountains.
Example:
- Aravalli Range
Landforms Created by Rivers
Rivers are the most important agents of erosion and deposition.
Erosional Features
V-Shaped Valley
- Formed in youthful stage of river.
Gorge
- Deep narrow valley with steep sides.
Waterfall
- Sudden drop in river course.
Example:
- Jog Falls
Depositional Features
Meander
- Curved bends in river course.
Oxbow Lake
- Crescent-shaped lake formed when meanders are cut off.
Flood Plain
- Flat fertile land along river banks.
Delta
- Formed at river mouth due to deposition.
Examples:
- Ganga-Brahmaputra Delta
- Nile Delta
Landforms Created by Glaciers
Glaciers are moving masses of ice.
Erosional Features
Cirque
- Bowl-shaped depression.
Arete
- Sharp ridge between two cirques.
Horn
- Pointed mountain peak.
Depositional Features
Moraine
- Deposited rock debris.
Drumlin
- Oval-shaped hill formed by glacial deposition.
Landforms Created by Wind
Wind is an important geomorphic agent in deserts.
Erosional Features
Mushroom Rock
- Rock shaped like a mushroom due to wind abrasion.
Yardang
- Long streamlined ridges formed by wind erosion.
Depositional Features
Sand Dunes
- Deposits of sand shaped by wind.
Types:
- Barchan Dunes
- Longitudinal Dunes
- Transverse Dunes
Loess
- Fine wind-deposited silt.
Coastal Landforms
Sea waves continuously erode and deposit sediments along coastlines.
Erosional Features
Sea Cliff
- Steep coastal slope.
Sea Cave
- Formed by wave action.
Sea Arch
- Natural arch in coastal rocks.
Stack
- Isolated rock pillar near coast.
Depositional Features
Beach
- Accumulation of sand and pebbles.
Spit
- Long narrow ridge of sand extending into sea.
Lagoon
- Shallow water body separated from sea.
Example:
- Chilika Lake
Volcanoes
A volcano is an opening through which molten magma, gases, and ash escape from the Earth’s interior.
Types of Volcanoes
Active Volcanoes
- Frequently erupt.
Dormant Volcanoes
- Temporarily inactive.
Extinct Volcanoes
- No possibility of future eruption.
Important Volcanoes
- Mount Vesuvius
- Mount Etna
- Barren Island
Earthquakes
An earthquake is the shaking of the Earth’s crust caused by sudden release of energy.
Key Terms
- Focus (Hypocenter): Point inside Earth where earthquake originates.
- Epicenter: Point directly above the focus on Earth’s surface.
Measurement
- Magnitude: Richter Scale / Moment Magnitude Scale.
- Intensity: Modified Mercalli Scale.
Important Geomorphological Terms for Exams
| Term | Meaning |
|---|---|
| Weathering | Breakdown of rocks in place |
| Erosion | Removal of weathered material |
| Deposition | Settling of transported material |
| Plateau | Elevated flat-topped land |
| Rift Valley | Depression formed due to faulting |
| Delta | River deposition at mouth |
| Moraine | Glacial debris |
| Lagoon | Coastal water body separated from sea |
| Meander | River bend |
| Oxbow Lake | Cut-off river meander |
Previous Exam-Oriented Facts
Earth’s core is mainly composed of iron and nickel.
Barren Island is India’s only active volcano.
Himalayas are the youngest fold mountains of the world.
Aravalli Range is among the oldest fold mountains in India.
Ganga-Brahmaputra Delta is the world’s largest delta.
Weathering occurs without transportation of material.
Plate Tectonic Theory explains continental movement and mountain formation.
