Tectonic forces result in the formation of original or tectonic mountains. When two continental plates clash, mountains develop. Mountains will rise higher and higher as the plates continue to clash. Rocks and debris are distorted and folded into rocky outcrops, hills, mountains, and whole mountain ranges as these clashing, compressing limits collide. The genesis of original or tectonic mountains is thus attributed to tectonic processes. This article will explain to you about Tectonic Mountains which will be helpful in Geography preparation for the UPSC Civil service exam.

What are Tectonic Mountains?

• Tectonic or orogenic mountains are formed primarily through the Earth's tectonic forces.
• These forces cause the Earth's crust to buckle, fold, or break, leading to the upliftment of mountain ranges.
• Tectonic mountains are a direct result of plate tectonics and encompass several types based on the specifics of the tectonic activity involved:
  • Fold Mountains
  • Block Mountains
  • Dome Mountains
• Mountains of Accumulations/ Volcanic Mountains
• Tectonic mountains play a vital role in understanding the Earth's geology and the movement of its tectonic plates.
• Their formation, growth, and erosion provide key insights into the dynamic processes shaping the Earth's surface over millions of years.

Classification of Tectonic Mountains

Fold Mountains

• Fold mountains are formed when two or more of the Earth's tectonic plates collide.
• Rocks and debris are distorted and folded into rocky outcrops, hills, mountains, and entire mountain ranges as a result of compression.
• Orogeny is the process by which fold mountains are formed.
• They form at convergent plate boundaries, which are also known as continental collision zones or compression zones.
• Tectonic activity forces crustal compression at the leading edge of crust formation at a compression zone.
• As a result, the majority of fold mountains are found on the edge or former edge of continental plate boundaries.
• Rocks near the edge of the continental crust are frequently weaker and less stable than rocks near the center of the continent.
• This makes them more prone to folding and warping.
• The majority of fold mountains are made up of sedimentary and metamorphic rock that formed under high pressure and relatively low temperatures.
• Many fold mountains form where there is an underlying layer of ductile minerals, such as salt.
• Example: The ancient Falklands Plateau collided with the African plate, forming the Cape Fold Mountains in South Africa.

Block Mountains

• Faults in the crust generate "block mountains," which are planes where rocks have moved past each other.
• Block mountains arise when rocks on one side of a fault rise relative to the other.
• These raised blocks are called the block mountains or horsts.
• Higher blocks are referred to as horsts, whereas troughs are referred to as grabens.
• Graben are the intervening dropped blocks, which can be smaller or larger enough to form rift valley systems.
• When the surface is stretched out, tensional forces are created, and when these tension forces break apart, the center block is pushed down.
• East Africa, the Vosges and Rhine valleys, and the Basin and Range Province of Western North America all have this type of topography.
• When the regional stress is extensional and the crust is weakened, these places are common.

Dome Mountains

• Dome mountains arise when enormous globs of magma float up from beneath the crust and push up top rocks, causing the crust to bulge in a rounded shape.
• When magma cools, it forms a huge dome of harder rock beneath the surface, which erosion occasionally exposes.
• Unlike a volcano, magma rarely reaches the surface of the Earth.
• Dome mountains seldom reach the heights of folded mountains because the magma beneath them does not press forcefully enough.
• The magma cools over time and becomes cold, hard rock. The outcome is a mountain in the shape of a dome.
• The Black Hills of South Dakota and the Adirondack Mountains of New York are two examples.

Mountains of Accumulations/Volcanic Mountains

• Volcanoes are generated when tectonic plates shift, and when volcanoes erupt, mountains are formed.
• Due to the low viscosity of the ejected material, which is mostly basalt, a shield volcano has a gently sloping cone.
• Due to the increased viscosity of the ejected material, the composite volcano or stratovolcano has a steeper rising cone (33°-40°), and eruptions are more severe and less frequent than shield volcanoes.
• The majority of volcanic mountains are found in a ring around the Pacific Ocean. They're known as the Pacific Ring of Fire as a whole.
• Stratovolcanoes, often known as shield volcanoes, are the most well-known volcanic mountains.
• Vesuvius and Mount Fuji are examples of stratovolcanoes, whereas Mauna Loa in Hawaii is an example of a volcanic mountain.

Possible Motions Between the Tectonic Plates

1. Separation or divergent or constructive plate margins
2. Closing together or convergent or destructive plate margins
3. Transform or conservative plate margin

Divergent Boundaries

• A divergent boundary is a boundary that is between two plates that are moving apart or rifting.
• Most active divergent plate boundaries exist as mid-oceanic ridges between oceanic plates.
• Tectonic plates migrate hundreds of kilometers apart from both sides of a diverging plate boundary over millions of years.
• As a result, rocks closest to a boundary on the same plate are younger than those further away.

Convergent Boundaries

• At a convergent boundary, plates collide and as such are sometimes called destructive boundaries because they result in the removal or compression of the surface crust.
• Convergent plate boundaries are responsible for some of the most massive and spectacular of earthly landforms: major mountain ranges, volcanoes, and oceanic trenches.

The three types of convergent boundaries are –

1. Oceanic–Continental Convergence
2. Oceanic–Oceanic Convergence
3. Continental–Continental Convergence

Oceanic–Continental Convergence

• As the oceanic lithosphere includes dense basaltic crust, it is denser than the continental lithosphere.
• In view of the above, the oceanic lithosphere always under-rides the continental lithosphere when they two collide.
• The dense oceanic plate slowly and inexorably sinks into the asthenosphere in the process of subduction.
• The subducting slab pulls on the rest of the plate (such slab pull is probably the main cause of most plate movement, pulling the rest of the plate in after itself, as it were).
• As deep-sea sediments and oceanic crust are scraped from the oceanic plate, an accretionary wedge emerges on the continental crust.
• Volcanic arcs develop on continental lithosphere as a result of partial melting caused by dehydration of the subducting slab's hydrous materials.

Oceanic–Oceanic Convergence

• If the convergent boundary is between two oceanic plates, subduction also takes place.
• As one of the oceanic plates subducts beneath the other, an oceanic trench is formed, shallow and deep-focus earthquakes occur and volcanic activity is initiated with volcanoes forming on the ocean floor.
• With time, a volcanic island arc (such as the Aleutian Islands and the Mariana Islands) develops; such an arc may eventually become a more mature island arc system (such as Japan and the islands of Sumatra and Java in Indonesia are today).
• As the slab descends deeper into the mantle, dehydration of hydrous minerals in the oceanic crust releases water.
• This water induces partial melting by lowering the melting temperature of rocks in the asthenosphere.
• Volcanic island arcs are formed as the partial melt travels up through the asthenosphere and eventually reaches the surface.

Continental-Continental Convergence

• Where there is a convergent boundary between two continental plates, no subduction takes place because the continental crust is too buoyant to subduct.
• Instead, huge mountain ranges, such as the Alps, are built up.
• The most dramatic present-day example of continental convergence is the formation of the Himalayas.

Tectonic Landforms and Features

• The movement of the plates has a tremendous ability to shape and deform rocks through a variety of processes that include faulting, folding, extension, and on a massive scale, mountain building.
• All large-scale landforms are the consequence of both tectonic and erosional processes that molded the relief of such locations into their unique shapes.
• Horst and Graben: Horst and Graben (valley and range) refer to a type of topography created when the earth's crust is pulled apart.
  • This process, called extension, can stretch the crust up to 100% of its original size.
  • As the crust is strained in this way, normal faults develop, and blocks of the crust drop down to form grabens or valleys.
• Tectonic Folding occurs when tectonic processes put stress on a rock, and the rock bends, instead of breaking.
  • This can create a variety of landforms as the surfaces of the folded rocks are eroded.
• Faults and Fractures: Faults are cracks in the earth’s crust along which movement occurs.
  • Fractures are cracks with no movement.

Conclusion

Plate tectonics is frequently linked to mountain creation. The orogenic process of mountain formation includes folding, faulting, volcanic activity, igneous intrusion, and metamorphism. Tectonic landforms are any relief features created largely by uplift or sinking of the Earth's crust or upward magmatic processes. Among them are mountains, plateaus, and rift valleys.

FAQs

Question. What are tectonic mountains?

Question. What causes tectonic mountains to form?

Question. What are some examples of tectonic mountains?

Question. What is the difference between tectonic mountains and volcanic mountains?

Question. How do tectonic mountains affect the environment?

MCQs

1. Which of the following is an example of tectonic mountains?

A) Mount Fuji

B) Himalayas

C) Mount Etna

D) Kilimanjaro

2. What is the main cause of tectonic mountain formation?

A) Volcanic activity

B) Glacial movement

C) Plate tectonics and movements

D) Weathering and erosion

3. Which mountain range is an example of collision-type tectonic mountain formation?

A) Andes

B) Alps

C) Himalayas

D) Rockies

4. What is the term used for the process of mountain building due to tectonic forces?

A) Erosion

B) Orogeny

C) Volcanism

D) Sedimentation

5. What is the primary difference between tectonic and volcanic mountains?

A) Tectonic mountains are formed by erosion; volcanic mountains are formed by earthquakes

B) Tectonic mountains are formed by plate movements; volcanic mountains by volcanic eruptions

C) Tectonic mountains are older than volcanic mountains

D) Tectonic mountains are smaller than volcanic mountains

GS Mains Questions and Model Answers

Q1: Explain the process of tectonic mountain formation and provide examples.

Answer: Tectonic mountain formation occurs when Earth's tectonic plates interact at their boundaries. Convergent plate boundaries, where plates collide, often lead to the formation of mountain ranges. For example, the Himalayas were formed by the collision of the Indian Plate with the Eurasian Plate. Divergent boundaries, where plates move apart, can also create mountain ranges like the Mid-Atlantic Ridge. In areas of transform boundaries, where plates slide past each other, mountains can also form, though these tend to be smaller in scale. The Andes Mountains were formed by the subduction of the Nazca Plate beneath the South American Plate. The ongoing movement of plates and the resulting tectonic forces continue to shape mountain ranges around the world.

Q2: Discuss the environmental impact of tectonic mountains on surrounding regions.

Answer: Tectonic mountains have a significant impact on the surrounding environment. They can influence local climate patterns by blocking wind and rain, creating different precipitation zones on either side of the mountains. This can lead to the development of deserts on the leeward side and lush vegetation on the windward side, a phenomenon known as the rain shadow effect. The steep terrain of tectonic mountains can cause erosion, leading to landslides and altering river systems. These mountains also create unique ecosystems and biodiversity, with species adapted to high altitudes. Additionally, tectonic mountains can affect human activities such as agriculture, settlement patterns, and infrastructure development due to their rugged nature.

Q3: Analyze the role of tectonic mountain chains in the shaping of global geographical features.

Answer: Tectonic mountain chains play a critical role in shaping global geographical features by acting as physical barriers that influence climate, biodiversity, and human settlement. For example, the Himalayas create a barrier between the Indian subcontinent and the Tibetan Plateau, influencing weather patterns and the monsoon system in the region. Similarly, the Rocky Mountains in North America serve as a barrier to the flow of air masses, affecting precipitation levels in the western United States. Tectonic mountain chains also influence river systems, such as the Ganges and Yangtze Rivers, which originate from mountains and shape the flow of water across vast regions. The geological history of these mountain chains also provides insights into plate tectonics, contributing to our understanding of Earth's dynamic surface processes.

Previous Year Questions on Original Tectonic Mountains

1. UPSC CSE 2017

Question: "Explain the formation of the Himalayan mountain range and its significance in the context of tectonic movements."

Answer: The Himalayan mountain range was formed as a result of the collision between the Indian Plate and the Eurasian Plate. This ongoing convergence began around 50 million years ago and continues today, causing the rise of the Himalayas. The tectonic forces of subduction and continental collision led to the uplift of the region. The Himalayas are significant as they are the highest mountain range in the world and play a crucial role in influencing climate patterns, such as the monsoon system in South Asia.

2. UPSC CSE 2019

Question: "Discuss the environmental consequences of the tectonic mountain-building process."

Answer: The tectonic mountain-building process leads to various environmental consequences. Mountains formed by tectonic movements often result in steep slopes, which increase the likelihood of soil erosion and landslides. They can create rain shadows, where one side of the mountain range is dry while the other receives heavy rainfall. Additionally, tectonic mountains affect local ecosystems by creating isolated environments where unique species evolve. The geological processes involved also contribute to the formation of river systems and the disruption of existing ecosystems. Human settlements near these mountains can face challenges like flooding, soil erosion, and infrastructure damage due to frequent seismic activity and landslides.