The lithosphere is the solid, outer layer of the earth which when broken into small pieces of plates, are called Lithospheric plates. The plates are in motion as they are floating on the molten magma inside the layer of the earth.

The changes on the surface of the earth’s layer are caused due to this movement of the lithospheric plates. The movement of the earth is divided in two categories on the basis of the forces. These forces are endogenous and exogenous forces.

Endogenous Forces

• These are the forces that act inside the earth.
• It is due to these endogenous forces which cause certain disruptions/mass destructions over the surface of the earth.
• These are primarily responsible for earthquakes or volcanic eruptions.

Volcano and Earthquake

The volcano is an opening in the topmost layer of the earth through which molten magma erupts out.

Earthquakes are vibrations caused by the movement of the lithospheric plates which move towards the surface of the earth.

Origin of Earthquake

• The vibrations caused by the movement of the lithospheric plates are termed as earthquakes.
• There exist 3 types of waves of earthquakes: P waves, which are also called Longitudinal waves, S waves, which are also called Transverse waves, and L waves, which are also called Surface waves.
• Earthquakes start from a point below the earth’s layer, and the point where the earthquake originates is called the focus.
• The point vertically above the focus of the earthquake on the surface of the earth is termed the epicentre.
• Epicentre is the point from where the vibrations of the earthquake start travelling outwards. The most critical area of destruction on the surface of the earth in the area near the epicentre from where the waves start travelling outward.

Exogenous Forces

• These are the forces that act on the earth’s surface.
• These are basically induced by Sunlight.
• These involve Wind, Water, and other forces acting above the surface of Earth.

Major Landforms

The landscape is continuously worn out by two processes, namely weathering and erosion.

Weathering: It is the process of breaking off the rocks on the surface of the earth.

Erosion: It is the removal of a layer of soil by different agents of removal such as water, ice, or wind. This carried away material is then settled at a different location and gets deposited there to form a different landform on the earth’s surface.

Factors Affecting Formation of Landforms: Glaciers

Glaciers are the rivers of ice that cause erosion on the landscape by removing the layer of soil or stones by the method of bulldozing, which exposes the soil or the solids below that layer.

The materials that are carried by the glaciers, for example: big and small rocks, sand, etc get deposited on other locations forming glacier moraines. Various types of landforms formed by glacial erosion are:

• Cirque
• Horns & Serrated ridges
• Troughs / Glacial valleys

Factors Affecting Formation of Landforms: Winds

The wind is considered to be an active agent for erosion and landscape formation in desert areas. Sand dunes are the structures formed due to the deposition of large amounts of sand at that particular location due to blowing wind. Loess is the deposition of fine grains of windblown sand over very long distances.

Various types of landforms created by the erosional and depositional activities of wind are:

• Pediplains
• Deflation hollows
• Mushroom tables
• Sand dunes
• Loess

Factors Affecting Formation of Landforms: Rivers

When a river falls/tumbles over a steep angle over hard rocks/stones it forms a waterfall. Thus, the kinetic energy of the water falling over steep angles causes erosion and is one of the primary reasons for erosion.

Water flowing over the surfaces also erodes the layer of earth and carries away the sand/soil of the particular layer and deposits at different locations forming a separate landscape. Rivers have 3 courses namely: upper course, middle course and the lower course.

Out of these 3 courses, the upper course is the part that sees most of the erosion. The upper course is the highest altitude point of the river from where the river starts falling. Floodplains are also formed by the deposition of fine grains of sand or other materials via floods in flood-affected areas.

Various types of landforms created by the erosional and depositional activities of rivers are:

• River valleys
• Waterfalls
• Potholes
• River terraces
• River meanders
• Peneplains

Factors Affecting Formation of Landforms: Sea Waves

The coastal landforms which have been formed are formed with the help of the erosion and the deposition work of the sea waves.

The eroded materials are carried away by the sea waves in various manners and leave behind certain types of landforms at the place of erosion or at the place of deposition. Various erosion and depositional landforms created by the sea waves are:

• Cliffs
• Sea caves
• Beaches
• Barriers and associated features
• Sabkha
• Coastal wetlands

FAQs

MCQs

1. What is the primary cause of mountain formation?

A) Volcanic eruptions
B) Tectonic plate movements
C) Erosion by water
D) Human activities

2. Which of the following is NOT a process that contributes to landform changes?

A) Weathering
B) Erosion
C) Plate tectonics
D) Pollution

3. What role do oceans play in shaping the Earth's surface?

A) Erosion of coastlines
B) Tectonic movements
C) Volcanic activity
D) All of the above

4. Which of the following is a major effect of plate tectonics?

A) Global warming
B) Earthquakes and volcanoes
C) Increased rainfall
D) Changes in ocean currents

5. How do human activities contribute to soil erosion?

A) Deforestation and agricultural activities
B) Plate tectonics
C) Earthquakes
D) Volcanic eruptions

GS Mains Questions and Model Answers

Q1: Discuss the various factors that contribute to the changing of Earth's surface and their implications for environmental sustainability.

Answer: The Earth's surface is constantly changing due to natural processes such as plate tectonics, erosion, weathering, and volcanic activity. These changes shape landforms, like mountains, valleys, and coastlines, and can lead to natural hazards such as earthquakes and landslides. Human activities, including deforestation, mining, and urbanization, also contribute to these changes by accelerating erosion, altering natural drainage systems, and depleting natural resources. Sustainable land management practices are essential to mitigate the negative impacts of human activities, maintain soil health, and reduce the risks of natural disasters.

Q2: How does understanding the Earth's changing surface help in disaster management and mitigation strategies?

Answer: Understanding the processes that cause changes in the Earth's surface, such as tectonic activity, erosion, and volcanic eruptions, is crucial for disaster management. It allows scientists and authorities to predict and monitor potential hazards, such as earthquakes, landslides, and volcanic eruptions. This knowledge aids in developing early warning systems, risk assessments, and disaster preparedness plans. For example, by understanding the tectonic plate movements, authorities can establish building codes to withstand seismic activity and implement land-use planning to avoid high-risk areas.

Q3: Explain the role of plate tectonics in shaping the Earth's surface and its impact on the environment.

Answer: Plate tectonics is the theory that explains the movement of Earth's lithosphere, which is broken into several tectonic plates. These plates float on the semi-fluid asthenosphere beneath them, and their movement results in various geological processes. The collision of plates leads to the formation of mountain ranges, such as the Himalayas, while plate divergence creates ocean ridges and new crust. Plate boundaries are also sites of volcanic activity and earthquakes, which can significantly impact the environment. The movement of tectonic plates thus reshapes the Earth's surface and affects the distribution of landmasses and oceans, leading to changes in ecosystems and climate patterns over time.

Previous Year Questions on Earth's Changing Surface

1. UPSC CSE Mains 2018 (GS Paper 1):

Question: "Explain the impact of tectonic activities on the Earth's surface and how they have shaped the present-day landscape of the Earth."

Answer: Tectonic activities have played a fundamental role in shaping the Earth's surface through processes such as mountain building, the formation of ocean basins, and the occurrence of earthquakes and volcanic eruptions. The movement of tectonic plates has led to the formation of landforms like mountain ranges, rift valleys, and fault lines. The shifting of plates has also contributed to the distribution of continents and oceans. The ongoing tectonic activity continues to shape the Earth, with implications for climate, ecosystems, and human societies.

2. UPSC CSE Mains 2020 (GS Paper 1):

Question: "Discuss the significance of understanding the processes that shape the Earth's surface in relation to environmental hazards and disaster risk reduction."

Answer: Understanding the processes that shape the Earth's surface, such as erosion, volcanic activity, and tectonic movements, is critical for identifying and mitigating environmental hazards. This knowledge helps in predicting natural disasters like earthquakes, landslides, and volcanic eruptions, enabling authorities to develop early warning systems and disaster preparedness strategies. It also aids in land-use planning and building codes that minimize the risk of damage during natural disasters, thereby reducing the loss of life and property.