Question.
Write a logical note on the Mountain building. (UPPSC 2021)
“Mountains have originated in geosynclines.” Explain this statement by giving suitable examples. ( UPPSC 2009)
What do you understand by plate tectonic? How far it has been able to solve the problems of mountain building and continental drift? ( UPPSC 2006)
Discuss the concept of plate tectonics and show how far it explains the formation of mountains and continental drift. ( UPPSC 2002)
Analyze concepts of mountain building. ( UPPSC 2001)
Discuss the role of Plate Tectonics in explaining mountain building. ( UPPSC 1999)
Account for the mountain-building process over the surface of the earth and examine critically the plate tectonic theory explaining their origin and evolution. ( UPPSC 1996)
Analyze any theory of mountain building that sheds light on the origin and structural features of the Himalayas. ( UPPSC 1991)
Answer.
Mountains are highlands that are usually 600 meters above sea level; And it has high relief, small summit, and wide base. There are three types of mountains:
- Fold mountain
- Block mountain
- Volcanic mountain
Orogeny is a mountain-building process that is a slow uplift process and is guided by endogenous forces.
There are two modern theories of mountain formation:
- Kober's geosyncline theory.
- Plate tectonic theory.
Kober's Geosyncline Theory:
It only explains the mountain-forming process of the folded mountain. According to Kober, most of the fold mountains of the world are formed on geo-syncline regions, which Kober called Cratogene.
For example,
- the Himalayas Mountains are built on the Tethys Sea( geosyncline region).
- The Andes Mountains are formed on the Andean geosyncline.
- Alps Mountains on the Alpine Geosyncline.
A geosyncline is a narrow and shallow water body that is bounded by two hard terrains. Kober called these hard terrains the foreground.
According to Kober,
Over time, sediments from these two hard terrains (foreground) continue to accumulate in the geosyncline regions. The rise of the geosyncline region in the fold mountains is a result of the compressive force generated during the earth's cooling. One of the main proofs of the theory is that all the fold Mountains are made of sedimentary rocks and that the remains of marine life are also found on these mountains.
Plate Tectonic theory:
It can interpret all three types of mountains - rings, blocks, and volcanoes.
Regarding the formation of fold mountain:
The Fold Mountains usually formed in the convergence zone of two continental plates or one continental plate and one oceanic plate.
For example,
- The Andes and the Rocky Mountains are formed at the convergence boundary of the oceanic plate (i.e. the Pacific Ocean Plate), and the continental plate (the American plate). Due to the heavy nature of the oceanic plate, the Pacific Ocean lifts up the American Plate on which the Andes and Rocky Mountains are formed.
- The Himalayan Mountains are formed on the convergence zone of two continental plates (Indian and Eurasian plates). One of the continental plates lifts the other plate resulting in the formation of the Himalayas Mountains.
Regarding the formation of volcanic mountains:
Volcanic mountains are formed over the subduction zone of the convergence of oceanic plates and continental plates.
For example,
- There are many volcanic mountains in the eastern part of the Andes and the Rocky Mountains. It is above the subduction zone of the Pacific Ocean.
- Volcanic island arcs are formed over the ocean in the convergence zone of two oceanic plates. For example, the Mariana and Tonga Islands have been created in this process.
- A mid-oceanic ridge is also a volcanic chain of mountains that forms on the divergence zone of two oceanic plates.
Regarding Block mountain formation:
Due to tensional forces, sometimes faults developed on the landscape, due to which some parts get pushed up and some parts get pushed down. The Harz Mountains and the Black Forest of Germany are examples of block mountains.
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