The surface of the Earth is not uniform. It has many different shapes — mountains, plateaus, plains, valleys, and more. These features are called landforms. Landforms influence climate, soil, vegetation, and the way people live.
---
Key Concepts
Landform: Any natural feature of the Earth's surface with a distinct shape. Landforms are formed by internal forces (tectonic activity) and external forces (erosion, weathering).
Mountain: A naturally elevated portion of the Earth's surface rising steeply above surrounding areas. Mountains above 1,000 m are significant. Example: Himalayas (fold mountains).
Plateau: A flat-topped elevated landform with at least one steep side (escarpment). Example: Deccan Plateau (India), Tibetan Plateau.
Plain: A large area of flat or gently rolling land. Plains are usually fertile and support dense populations. Example: Indo-Gangetic Plain.
Valley: A low-lying area between hills or mountains, often with a river. V-shaped valleys are formed by rivers; U-shaped by glaciers.
Desert: A barren area receiving very little rainfall (less than 25 cm annually). Example: Thar Desert, Sahara Desert.
Glacier: A slow-moving mass of ice. Glaciers shape valleys and deposit sediment.
Volcano: An opening in the Earth's surface through which molten rock (lava), ash, and gases escape.
---
Types of Mountains
- Fold Mountains: Formed by folding of crustal rocks due to compression. Example: Himalayas, Alps, Rockies.
- Block Mountains (Horst): Formed when blocks of crust are uplifted along faults. Example: Vosges (France), Black Forest (Germany).
- Volcanic Mountains: Formed by volcanic activity. Example: Mount Fuji (Japan), Mount Kilimanjaro (Africa).
---
Worked Examples
How do fold mountains like the Himalayas form?
- When two tectonic plates collide, the rocks between them are compressed and folded upward, forming fold mountains. The Indian Plate pushing into the Eurasian Plate created the Himalayas.
Why are plains the most densely populated landforms?
- Plains have flat, fertile land suitable for agriculture. They have good water supply from rivers and easy transportation. The Indo-Gangetic Plain supports hundreds of millions of people.
What is the difference between a plateau and a plain?
- A plateau is elevated (raised above surrounding land) and has a flat top with at least one steep cliff-like side. A plain is at low elevation and is almost flat without steep sides.
Why do rivers form V-shaped valleys?
- A fast-flowing river cuts vertically downward into the rock, eroding the valley floor more than the sides, creating a narrow V-shape. Glaciers, which are wider and move slowly, erode both the floor and sides equally, forming a U-shape.
How do deltas form?
- When a river slows down near the sea or a lake, it deposits the sediment it has been carrying. Over time, this sediment builds up to form a triangular landform called a delta. Example: Sundarbans delta (Ganga-Brahmaputra).
Name and describe two landforms found in India.
- Deccan Plateau: A large triangular plateau south of the Vindhya mountains; one of the world's oldest landforms; rich in minerals like iron ore and coal.
- Indo-Gangetic Plain: A vast fertile alluvial plain stretching across northern India; formed by sediment deposited by the Indus, Ganga, and Brahmaputra rivers.
Why is the Tibetan Plateau called the "Roof of the World"?
- The Tibetan Plateau has an average elevation of about 4,500 metres above sea level — the highest and largest plateau in the world. The Himalayas border it to the south.
---
Key Formulas / Facts
- Mountain: typically above 1,000 m elevation
- Desert: rainfall less than 25 cm per year
- Delta: Greek letter delta (triangle) — named for its triangular shape
---
Common mistakes
Common mistakes
Students confuse plateaus with plains. Remember — a plateau is elevated with steep sides; a plain is at low altitude and gently rolling. Also, fold mountains are NOT formed by volcanic activity; volcanic mountains are a separate category.
---
Summary
Landforms include mountains, plateaus, plains, valleys, deserts, and glaciers. They are formed by tectonic forces, erosion, and deposition. Landforms greatly influence human settlement, agriculture, and economic activities. Plains are the most populated landforms, while mountains and deserts have sparse populations.