Major Landforms of the Earth
Introduction — Why Landforms Matter
The Earth's surface is NOT smooth and flat. It has VARIED RELIEF — mountains, plateaus, plains, valleys, and hills. These LANDFORMS shape HUMAN LIFE: they determine where we settle, what we grow, how we travel, and even our CLIMATE.
'Landforms give the Earth its CHARACTER. They are the SCULPTURES created by internal and external forces over millions of years.'
Internal and External Forces
| Force | Source | Effect |
|---|---|---|
| Internal (Endogenic) | INSIDE the Earth. Heat from the core. Plate movements. | BUILD landforms — create mountains, volcanoes, earthquakes. |
| External (Exogenic) | ABOVE the Earth. Wind, water, ice. | WEAR DOWN landforms — erosion, weathering, deposition. |
Major Landforms — Overview
| Landform | Height | Shape | Examples |
|---|---|---|---|
| Mountains | OVER 600 m above sea level | HIGH elevation. STEEP slopes. | Himalayas, Andes, Rockies |
| Plateaus | Varies (can be high or low) | FLAT-TOPPED. Steep sides. 'Table land.' | Deccan Plateau, Tibetan Plateau |
| Plains | LOW elevation (under 200 m) | FLAT or gently rolling. | Indo-Gangetic Plain, Amazon Basin |
Mountains — The Highest Landforms
A MOUNTAIN is a landform that rises MORE than 600 metres above the surrounding land. Mountains usually occur in GROUPS (mountain RANGES or SYSTEMS).
Types of Mountains
1. Fold Mountains — The MOST COMMON Type
How They Form: When Earth's tectonic plates COLLIDE, the crust is COMPRESSED and FOLDS upward — like a rug pushed against a wall.
Examples:
| Mountain Range | Location | Age |
|---|---|---|
| Himalayas | Asia (India-China border) | YOUNG (still rising ~5 cm/year) |
| Andes | South America (western edge) | YOUNG (longest range: 7,000 km) |
| Rockies | North America (western USA/Canada) | MODERATELY YOUNG |
| Alps | Europe | YOUNG |
'The Himalayas are the HIGHEST and one of the YOUNGEST mountain ranges. They are STILL RISING — because the Indian plate continues to push into the Eurasian plate.'
2. Block Mountains
How They Form: When Earth's crust develops FAULTS (cracks) and blocks of land are either LIFTED UP (horsts) or DROPPED DOWN (grabens / rift valleys).
Examples:
- Vosges Mountains (France) — a lifted block
- Black Forest (Germany) — a lifted block
- Rift Valley (East Africa) — a dropped block
3. Volcanic Mountains
How They Form: When MAGMA from inside the Earth erupts through the crust and COOLS, it builds up LAYER by layer.
Examples:
- Mt Fuji (Japan) — beautifully symmetrical cone
- Mt Kilimanjaro (Tanzania) — highest mountain in Africa
- Mt Vesuvius (Italy) — destroyed Pompeii in 79 CE
- Mt Krakatoa (Indonesia) — famous for 1883 eruption
Why Mountains Are Important
| Benefit | Explanation |
|---|---|
| Water Source | Glaciers and snowmelt feed MAJOR rivers (Ganga, Indus, Brahmaputra) |
| Climate | Block winds → cause RAINFALL on windward side |
| Biodiversity | Different altitudes = different climates = DIFFERENT species |
| Tourism | Scenic beauty. Hill stations. Adventure sports. |
| Minerals | Rich in MINERAL deposits |
| Defence | Natural BORDERS between countries |
Plateaus — The Table Lands
A PLATEAU is an elevated FLAT-TOPPED area with steep sides. It looks like a TABLE (hence 'table land').
Types of Plateaus
| Type | How Formed | Example |
|---|---|---|
| Intermontane Plateau | SURROUNDED by mountains | Tibetan Plateau (highest in world, 4,500 m) |
| Piedmont Plateau | At the FOOT of a mountain | Deccan Plateau (India) |
| Continental Plateau | Far from mountains, often BORDERED by oceans | Western Plateau of Australia |
Famous Plateaus of the World
| Plateau | Location | Key Feature |
|---|---|---|
| Tibetan Plateau | China/Tibet | HIGHEST plateau in the world. 'Roof of the World.' |
| Deccan Plateau | Central and South India | VERY OLD (shield rock). Rich in MINERALS. |
| Colorado Plateau | USA | GRAND CANYON carved into it by the Colorado River. |
| Brazilian Highlands | Brazil | Covers much of eastern South America. |
Why Plateaus Are Important
- RICH in MINERALS (iron, coal, gold, diamonds) — Deccan and Brazilian plateaus
- Excellent for WATERFALLS (rivers fall off the edges) — HYDROELECTRIC power
- LAVA plateaus have FERTILE SOIL (black soil of the Deccan — great for cotton)
Plains — The Flat Lands
PLAINS are FLAT or GENTLY ROLLING areas of land, usually at LOW elevation (under 200 metres above sea level). They are the MOST DENSELY POPULATED landform.
Types of Plains
| Type | Formation | Example |
|---|---|---|
| Structural Plains | Originally horizontal layers of rock | Russian Plain |
| Depositional Plains | Built up by RIVERS depositing soil | Indo-Gangetic Plain, Amazon Basin |
| Glacial Plains | Shaped by GLACIERS | Northern European Plain |
Why Plains Are Important
- FERTILE soil — ideal for AGRICULTURE
- FLAT land — easy to BUILD cities, roads, railways
- RIVERS provide WATER for irrigation
- HIGHEST population density — MOST people live on plains
Weathering and Erosion
Weathering
The BREAKDOWN of rocks at or near the Earth's surface. Types:
- Physical Weathering: Temperature changes, frost, wind
- Chemical Weathering: Rainwater dissolving minerals (cave formation)
- Biological Weathering: Roots growing into cracks
Erosion
The TRANSPORT of weathered material by wind, water, or ice. 'Erosion WEARS DOWN landforms. Deposition BUILDS them up elsewhere.'
ICSE Exam Focus
| Question Type | Marks | Likely Topics |
|---|---|---|
| Short Answer | 3 | Describe the three types of mountains with examples |
| Short Answer | 2 | What is a plateau? Give examples |
| Short Answer | 2 | Why are plains densely populated? |
| Short Answer | 2 | Difference between fold and block mountains |
| MCQ | 1 | Types / examples / formation |
Common Mistakes in ICSE Exams
- Saying the Himalayas are the LONGEST — They are the HIGHEST. The ANDES are the LONGEST.
- Confusing 'weathering' and 'erosion' — Weathering = BREAKING DOWN rocks. Erosion = CARRYING AWAY the pieces.
- Forgetting that the Deccan Plateau is a SHIELD plateau — It is one of the OLDEST parts of the Earth's crust.
- Saying all mountains are the same age — Fold mountains like the Himalayas are YOUNG. Others (Aravallis, Appalachians) are OLD.
Self-Test: 5 Questions
Q1. What are the THREE types of mountains? Give an example of each. A1. (1) FOLD MOUNTAINS — formed by colliding plates folding the crust. Example: HIMALAYAS (Asia), also Andes, Rockies, Alps. (2) BLOCK MOUNTAINS — formed by faulting, where blocks of crust are lifted or dropped. Example: VOSGES (France), Black Forest (Germany). (3) VOLCANIC MOUNTAINS — formed by eruption and cooling of magma. Example: MT FUJI (Japan), Mt Kilimanjaro (Tanzania).
Q2. How are FOLD MOUNTAINS formed? Why are the Himalayas still RISING? A2. Fold mountains form when two TECTONIC PLATES collide. The pressure FOLDS the Earth's crust upward like a rug pushed against a wall. The HIMALAYAS are still rising (about 5 cm/year) because the INDIAN PLATE continues to push northward into the EURASIAN PLATE. They are YOUNG mountains — still growing.
Q3. What is a PLATEAU? Why is the Deccan Plateau important for India? A3. A plateau is an elevated FLAT-TOPPED landform ('table land') with steep sides. The DECCAN PLATEAU is one of the OLDEST parts of the Earth's crust. It is important because: (1) RICH MINERALS — iron, coal, gold, diamonds. (2) BLACK SOIL — formed from ancient lava — excellent for COTTON. (3) WATERFALLS — rivers falling off edges provide HYDROELECTRIC power.
Q4. Why are PLAINS the most DENSELY POPULATED landform? A4. Plains are densely populated because: (1) FERTILE SOIL — deposited by rivers, perfect for farming. (2) FLAT LAND — easy to build cities, roads, railways, and airports. (3) WATER AVAILABILITY — rivers provide drinking water and irrigation. (4) MODERATE CLIMATE — plains are usually neither too hot nor too cold. (5) ECONOMIC ACTIVITY — agriculture, industry, and trade all flourish on plains.
Q5. Distinguish WEATHERING and EROSION. A5. WEATHERING is the BREAKDOWN of rocks at or near the Earth's surface. The rock is BROKEN INTO SMALLER PIECES but stays IN PLACE. Types: physical (frost), chemical (rain dissolving rock), biological (roots). EROSION is the TRANSPORT of weathered material to another location — by wind, water, or ice. Weathering prepares the material. Erosion MOVES it.
