Question.
Examine the recent views on the mountain-building process and divide the world's mountains on the basis of their genesis.
( UPSC 2024 Geography Paper 1)
Answer.
Mountain-building or orogenesis refers to the geological processes that lead to the formation of mountains.
Recent advancements, particularly in Plate Tectonics Theory, have reshaped our understanding of how mountains are formed.
Recent Views on Mountain-Building Processes:
1. Plate Tectonics Theory (Modern View):
It is the most accepted theory.
Mountains form primarily due to convergent plate boundaries:
Continental–Continental collision → Fold mountains (e.g., Himalayas).
Oceanic–Continental subduction → Volcanic mountains (e.g., Andes, Rocky).
2. Kober's Geosynclinal Theory (Geosynclinal Theory by Alfred Kober):
German geographer Alfred Kober proposed a significant theory related to mountain building, known as the Geosynclinal Theory. This theory predates the Plate Tectonics concept and explains the process of mountain formation from a narrow perspective.
According to Kober:
- Certain regions of the Earth's crust accumulate sediments over a long period, resulting in the formation of geosynclines.
- These geosynclines are vast, trench-like structures where sedimentary materials get deposited continuously for millions of years.
- Later, stable landmasses on either side of the geosyncline—referred to as Kratogens—begin exerting pressure from both sides.
- This pressure compresses and uplifts the geosynclinal zone, resulting in the formation of mountain ranges.
Classification of Mountains Based on Genesis:
1. Fold Mountains:
Fold mountains form due to Compression forces at convergent boundaries of two plates.
Examples: Himalayas, Alps, Rockies, and Andes.
2. Block Mountains:
Formed by faulting (normal faults).
Examples: Vosges (France), the Black Forest (Germany), the Sierra Nevada (USA).
3. Volcanic Mountains:
Formed by volcanic activity due to hotspots or subduction.
Example: Mount Fuji, Mount Kilimanjaro, Hawaiian Islands.
4. Residual Mountains:
Eroded remnants of ancient mountains;
Examples: Aravallis (India), Sierra (Spain)
5. Dome Mountains:
Formed due to the intrusion of magma pushing rock layers upward
Examples: Adirondacks (USA), the Elburz (Iran)
Conclusion
Recent geoscientific advancements highlight that mountain-building is a dynamic and ongoing process driven by plate tectonics and mantle dynamics.
The classification of mountains based on genesis allows geographers to better understand the diverse landscapes and tectonic history of Earth.
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