Volcanic Landforms - NCERT Geography UPSC Notes
Volcanic Eruption is said to occur when the lava and other gases that are inside the volcano are discharged from the volcanic vent. Candidates can read other NCERT Geography notes to prepare for UPSC IAS Prelims and Mains exam.
Lava inside the volcano is termed magma. Volcanoes erupt when the magma rises to the earth’s surface.
|
Table of Contents
|
After the volcanic eruption, the magma can either cool within the crust or on the surface of the earth. Rocks that are formed due to the cooling of magma inside the earth’s crust are called Plutonic rocks. Rocks that are formed due to the cooling of Lava on the earth’s surface are called Igneous Rocks.
Volcanic landforms are the landforms that are formed due to volcanic eruptions. Depending on the place where the magma cools, Volcanic Landforms can be classified into two types. They are:
- Intrusive Landforms
- Extrusive Landforms
Intrusive Volcanic Landforms
The Magma that cools inside the earth’s crust takes various forms called Intrusive Volcanic Landforms. The various Intrusive Landforms are as follows: Batholiths, Laccoliths, Lopoliths, Phacoliths, Sills, and Dykes.
Batholiths
- Batholiths are formed due to the solidification of hot magma inside the earth’s crust.
- They are in the form of large domes.
- They are the large granitic rock bodies formed at the core of the huge mountains.
| Relevant Links for NCERT Geography Notes | ||
|---|---|---|
| The Major Indian River System | National Waterways in India | Ocean Floor and its Features |
| Types Of Clouds | Volcanoes | Biogeochemical Cycles |
Laccoliths
- Laccoliths are large dome-shaped intrusive bodies that are connected to the Batholiths by a pipe-like channel.
- These are located at the deeper depths of the earth’s crust but above the Batholiths.
- The Karnataka plateau has dome hills of granite rocks.
Lopoliths
- Magma in its way during eruption moves in the horizontal direction and rests in different forms wherever it finds a weak plane.
- If it forms a saucer-like shape of concave to the sky body then it is called Lopoliths.
Phytoliths
- Phacolith is a wavy mass of igneous rock parallel to the bedding plane of folded country rock.
- It is a lens-shaped pluton.
- It either occupies the crest of an anticline or the trough of a syncline.
Sills and Sheets
- Some amount of the Lava moves in the horizontal direction wherever possible which on solidification forms igneous rocks in the same horizontal direction.
- The thick horizontal deposits of igneous rocks are called the Sills. The thin horizontal deposits of igneous rocks are called the Sheets.
- The sills and sheets are not deep inside the earth’s crusts. They are formed nearer to the earth’s surface.
Dykes
- At the time of the volcanic eruption, the magma finds its way out through all possible ways like cracks and fissures in the land.
- This magma present in the cracks and the fissures gets cooled in the same position and forms a wall-like structure called Dykes.
- The Dykes are almost perpendicular to the earth’s crust.
- The Dykes are commonly found in the western Maharashtra region.
Extrusive Volcanic Landforms
The Lava that is thrown out onto the earth’s surface during the volcanic eruption takes various forms called Extrusive Volcanic Landforms. The various Extrusive Landforms are as follows: Conical vent and Fissure vent, Composite type Volcanic Landforms, Caldera, Crater.
Conical Vent and Fissure Vent
- Fissure Vent: A narrow, linear vent through which the magma comes out without any explosion activity is known as the Fissure Vent. These are commonly found in Shield type Volcanoes.
- Conical Vent: A narrow, cylindrical vent through which the magma erupts during an explosion is known as the Conical Vent. These are commonly found in Composite type Volcanoes.
Composite Type Volcanic Landforms
- The Composite type volcanic landforms are the conical type landforms.
- Along with Lava or Igneous rock, a large amount of pyroclastic material and ashes can be found on the surface of this landform.
- Mount Fuji, Mount Vesuvius, Mount Stromboli are examples of Composite type volcanic landforms.
Caldera
- Sometimes after the volcanic eruption, all the magma present inside the volcano erupts out creating an empty chamber below the earth’s surface.
- This leads to the collapsing of the volcanic material above into the volcanic chamber.
- This forms a hollow tube-like shape called the Caldera.
- It also appears as a Caldera lake when the rain waters or melted snow gets accumulated in it.
Crater
- An inverted cone-shaped vent through which the magma flows out on eruption is called the crater.
- An inactive crater appears as a bowl-shaped depression.
- It also appears as a crater lake when the rain waters or melted snow gets accumulated in it.
- Lake Toba is the largest Crater Lake in the world.
FAQs
Question: What are volcanic landforms?
Answer: Volcanic landforms are geological structures created by volcanic activity, including volcanoes, lava flows, ash deposits, and volcanic cones.
Question: What types of volcanic landforms exist?
Answer: Types of volcanic landforms include shield volcanoes, stratovolcanoes, cinder cones, and lava plateaus, each formed by different types of volcanic eruptions.
Question: How do shield volcanoes differ from stratovolcanoes?
Answer: Shield volcanoes have broad, gentle slopes and are formed by low-viscosity basaltic lava, while stratovolcanoes have steeper slopes and are built from alternating layers of lava and ash.
Question: What role do tectonic plates play in the formation of volcanic landforms?
Answer: Tectonic plates interact at boundaries, causing magma to rise to the surface, leading to volcanic eruptions and the formation of various volcanic landforms.
Question: Can volcanic landforms affect climate?
Answer: Yes, volcanic eruptions can inject ash and gases into the atmosphere, which can lead to temporary cooling and changes in climate patterns.
MCQs
- Which of the following is a characteristic of shield volcanoes?
a) Steep slopes
b) Formed by explosive eruptions
c) Broad, gentle slopes
d) Primarily composed of ash
Answer: (C) See the Explanation
Broad, gentle slopes. Shield volcanoes are characterized by their broad and gentle slopes formed by the flow of low-viscosity lava.
- What type of volcano is formed primarily from explosive eruptions?
a) Shield volcano
b) Cinder cone
c) Stratovolcano
d) Lava plateau
Answer: (C) See the Explanation
Stratovolcano. Stratovolcanoes are known for their explosive eruptions and steep profiles.
- Which gas is primarily released during volcanic eruptions?
a) Carbon dioxide
b) Nitrogen
c) Water vapor
d) Oxygen
Answer: (C) See the Explanation
Water vapor. Water vapor is one of the most abundant gases emitted during volcanic eruptions.
- Lava plateaus are formed by which type of volcanic activity?
a) Explosive eruptions
b) Extensive lava flows
c) Pyroclastic flows
d) Ash falls
Answer: (B) See the Explanation
Extensive lava flows. Lava plateaus are formed from large amounts of low-viscosity lava that flow over extensive areas.
- What is a primary cause of volcanic eruptions?
a) Erosion
b) Weathering
c) Magma movement
d) Sedimentation
Answer: (C) See the Explanation
The correct answer is c) Magma movement. Volcanic eruptions occur when magma from beneath the Earth's crust rises to the surface.
GS Mains Questions and Model Answers
Q1: Discuss the impact of volcanic landforms on human activities.
Answer: Volcanic landforms can significantly impact human activities in various ways. Areas surrounding active volcanoes can be fertile due to the mineral-rich volcanic soil, benefiting agriculture. However, the risk of eruptions poses threats to communities, infrastructure, and ecosystems. Major eruptions can lead to loss of life, displacement of populations, and economic losses due to damage to property and agriculture. Additionally, volcanic ash can disrupt air travel and cause respiratory problems. Long-term effects can include changes in landscape, climate patterns, and the creation of new landforms, influencing land use and development.
Q2: Analyze the relationship between tectonic plate movements and volcanic activity.
Answer: The relationship between tectonic plate movements and volcanic activity is intrinsic to the formation of volcanoes. Volcanic eruptions often occur at plate boundaries, where plates converge, diverge, or slide past one another. At convergent boundaries, subduction zones create conditions for magma formation as one plate is forced beneath another. Divergent boundaries allow magma to rise as plates separate, forming new crust. Intraplate volcanic activity can also occur due to hotspots, where magma plumes from the mantle breach the crust. This interplay leads to the formation of diverse volcanic landforms and contributes to the Earth's geological evolution.
Q3: Evaluate the significance of studying volcanic landforms in understanding Earth's geological processes.
Answer: Studying volcanic landforms is crucial for understanding Earth's geological processes as they provide insights into the dynamics of magma movement, eruption mechanisms, and tectonic activity. Volcanic landforms serve as natural laboratories for examining the behavior of volcanic eruptions and the subsequent landscape evolution. This knowledge aids in hazard assessment, which is vital for disaster preparedness and mitigation. Additionally, understanding the role of volcanoes in shaping the Earth's surface contributes to broader geological models, including plate tectonics and climate interactions. Furthermore, the study of volcanic landforms enhances our understanding of natural resources, as many mineral deposits are associated with volcanic activity.
Previous Year Questions on Volcanic Landforms
1. UPSC CSE Mains 2020
Question: Discuss the environmental impacts of volcanic eruptions.
Answer: Volcanic eruptions have significant environmental impacts, affecting air quality, climate, and ecosystems. Eruptions release ash and gases like sulfur dioxide, which can lead to acid rain and respiratory issues. Ashfall can devastate agricultural areas, leading to food shortages. The cooling effect from ash and aerosols can alter climate patterns temporarily. Ecosystems may be disrupted as habitats are destroyed, but volcanic soil can also enrich areas post-eruption. Long-term impacts include the formation of new landforms and the potential for increased geothermal energy resources. Understanding these impacts is essential for ecological management and disaster response.
2. UPSC CSE Prelims 2019
Question: How do volcanic eruptions contribute to the formation of new landforms?
Answer: Volcanic eruptions contribute to the formation of new landforms through the deposition of lava, ash, and other volcanic materials. The accumulation of lava creates shield volcanoes and lava plateaus, while explosive eruptions can form stratovolcanoes and cinder cones. The landscape can be significantly altered by pyroclastic flows and volcanic ash deposits, which reshape the terrain. Over time, these landforms evolve, leading to the creation of calderas and volcanic islands. Understanding these processes is vital for studying the Earth's geological history and predicting future volcanic activity.
Download the PREPP App and attempt FREE IAS Exam Mock Tests and get complete study material!
Full Test - 02: UPSC CSE Prelims CSAT (Paper-II)
Full Test - 01: UPSC CSE Prelims CSAT (Paper-II)
UPSC CSE Prelims 2026 GS Paper 1 Question Paper (24-May-2026)
UPSC CSE Prelims 2026 CSAT Paper 2 Question Paper (24-May-2026)
17 February 2025 | The Hindu Must Read Articles | Current Affairs
16 February 2026 | The Hindu Must Read Articles | Current Affairs
13 February 2026 | The Hindu Must Read Articles | Current Affairs
Comments