Mountains, plateaus, plains, and lakes represent some of the primary landforms on Earth’s surface, shaped by external (exogenic) and internal (endogenic) forces.
Mountains
Mountains are classified as second-order landforms, covering about 27% of the planet’s land area and serving as the source of 80% of Earth’s surface freshwater. These vast landforms arise from tectonic activity or volcanic processes.
Key Terms Related to Mountains
- Mountain Ridge: A series of long, narrow, and elevated hills.
- Mountain Range: A system of interconnected mountains, hills, and valleys.
- Mountain Chain: Several parallel mountain systems from various geological periods.
- Mountain System: Comprises different mountain ranges of the same geological era.
- Mountain Group: A cluster of mountain systems arranged in irregular patterns.
- Cordillera: An extensive grouping of mountain systems and ranges.
Types of Mountains
Mountains can be categorized based on location, geological period, and mode of origin.
Based on Location
- Continental Mountains: Found on continents, such as the Rockies and Appalachians.
- Coastal Mountains: Located near coastlines, like the Western and Eastern Ghats in India.
- Oceanic Mountains: Found on continental shelves or the ocean floor, e.g., Mauna Kea.
Based on Geological Period
- Precambrian Mountains: Over 4 billion years old, characterized by denuded and metamorphosed rocks (e.g., Laurentian Mountains).
- Caledonian Mountains: Formed around 430–380 million years ago during significant tectonic movements (e.g., Appalachians, Aravallis).
- Hercynian Mountains: Emerged between the Carboniferous and Permian periods (e.g., Vosges, Tien Shan).
- Alpine Mountains: Created tens of millions of years ago by tectonic collisions (e.g., Alps).
Based on Origin
- Fold Mountains: Result from the folding of crustal rocks due to compressive forces. Examples include the Himalayas.
- Volcanic Mountains: Formed by volcanic activity (e.g., Mauna Loa, Mount Fuji).
- Block Mountains: Created by large-scale faulting, with uplifted blocks (horsts) and lowered blocks (grabens), e.g., the Great African Rift Valley.
- Residual Mountains: Shaped by erosion of existing mountains, such as the Aravallis and Vindhyas.
Major Mountain Ranges
| Mountain Range | Type | Location | Key Features |
|---|---|---|---|
| Himalayas | Young Fold Mountains | Indian Subcontinent | Home to peaks like Everest and Kanchenjunga. |
| Andes | Young Fold Mountains | South America | Longest continental mountain range. |
| Rockies | Young Fold Mountains | North America | Part of the American Cordillera. |
| Urals | Old Fold Mountains | Western Russia | Extends north-south through Russia. |
| Alps | Young Fold Mountains | Europe | Most extensive in Europe; includes Mont Blanc. |
| Western Ghats | Block Mountain | India | A biodiversity hotspot; includes Anaimudi. |
Plateaus
Plateaus are elevated flatlands covering 18% of Earth’s surface, formed by processes such as volcanism, crustal shortening, and thermal expansion.
Types of Plateaus
- Intermontane Plateaus: Surrounded or enclosed by mountains (e.g., Tibetan Plateau).
- Piedmont Plateaus: Found at mountain bases (e.g., Malwa Plateau).
- Continental Plateaus: Resulting from extensive uplift or lava flows (e.g., Deccan Plateau).
- Volcanic Plateaus: Formed by lava accumulation (e.g., Snake Plateau).
- Dissected Plateaus: Created by tectonic uplift and erosion (e.g., Colorado Plateau).
Plains
Plains are flat or gently rolling lands occupying about 55% of Earth’s surface. Most are formed by sediment deposition from rivers, glaciers, or wind, with an average height below 200 meters.
Types of Plains
- Outwash Plains: Formed by glacial meltwater (e.g., Iceland’s outwash plains).
- Till Plains: Created by glacial deposits.
- Floodplains: Formed by river deposition during flooding.
