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GNDU Question Paper-2022
B.A 1
st
Semester
GEOGRAPHY
(Physical Geography-l: Geomorphology)
Time Allowed: Three Hours Maximum Marks: 75
Note: Attempt Five questions in all, selecting at least One question from each of the Four
Sections A, B, C and D. The Fifth question may be attempted from any Section. All
questions carry equal marks.
SECTION-A
1. Critically examine the Tidal Hypothesis regarding origin of the Earth as given by Jean
and Jeffery.
2. Discuss the continental drift theory given by Alfred Wegner.
SECTION-B
3. What is Fold? Give a detailed account of different kinds of Folds with the help of
suitable diagrams.
4. What is an Earthquake? Discuss the causes behind the occurrence of Earthquake.
SECTION-C
5. What is a Rock? Give a detailed account of igneous rocks.
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6. Define a Plateau. Discuss the different types of plateaus with help of suitable examples.
SECTION-D
7. Discuss the work of wind as an agent of Denudation.
8. Discuss the application of Geomorphology in the human activities.
GNDU Answer Paper-2022
B.A 1
st
Semester
GEOGRAPHY
(Physical Geography-l: Geomorphology)
Time Allowed: Three Hours Maximum Marks: 75
Note: Attempt Five questions in all, selecting at least One question from each of the Four
Sections A, B, C and D. The Fifth question may be attempted from any Section. All
questions carry equal marks.
SECTION-A
1. Critically examine the Tidal Hypothesis regarding origin of the Earth as given by Jean
and Jeffery.
Ans: What is the Tidal Hypothesis?
The Tidal Hypothesis, also known as the Catastrophic Theory of Earth’s Origin, was proposed
in 1917 by Sir James Jeans and later supported by Sir Harold Jeffreys. It tries to explain the
formation of planets, including Earth, in relation to the Sun.
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At its heart, the theory suggests that:
• A massive star once passed very close to our Sun.
• The gravitational pull from this passing star created huge tidal waves (just like the
Moon affects tides on Earth, but much more powerful).
• These tidal waves pulled large streams of hot gas out of the Sun.
• This ejected matter eventually cooled down, condensed, and formed the planets,
including Earth.
• It was a catastrophic theory—meaning it depended on a rare, violent event rather
than a slow, natural process.
Key Concepts in the Tidal Hypothesis
To understand this theory better, let’s look at its main components step-by-step:
1. Close Encounter of a Passing Star
The hypothesis begins with a wandering, massive star coming close to the Sun. This is a one-
time cosmic accident, not a regular event. The gravitational field of the star distorts the
Sun's shape and causes powerful tides.
2. Gravitational Tides on the Sun
Just as the Moon causes tides on Earth by pulling at the oceans, this star pulls at the Sun’s
hot, gaseous surface. Due to the massive force of gravity, the Sun’s material stretches out in
the direction of the star, forming long streamers of gas.
3. Formation of Planetary Material
Some of the gas pulled out from the Sun gets ejected into space. Over time, this matter
cools and starts to break up into smaller fragments. These fragments condense into solid
bodies—what we now call planets.
4. Cooling and Condensation
As the ejected gases cool over millions of years, they shrink, become solid, and start moving
around the Sun in orbits. These are the proto-planets, and with time, they develop into the
planets of our solar system.
Support for the Tidal Hypothesis
In the early 20th century, this theory gained popularity for several reasons:
• It explained the similarity of chemical composition between the Sun and the planets.
• It seemed to provide a rational explanation for why all the planets lie more or less in
the same plane and revolve around the Sun in the same direction.
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• The concept of gravity as a shaping force made sense and was supported by
Newtonian physics.
Critical Examination: Strengths and Weaknesses
Now let us examine this theory critically. What makes it appealing, and where does it fall
short?
Strengths of the Tidal Hypothesis
Gravitational Logic:
The theory correctly emphasizes the role of gravitational forces. In fact, modern theories of
planetary formation also recognize gravity as a key factor.
Explains Planetary Orbits and Spin:
The theory provides a possible reason for why planets orbit in the same direction and lie
roughly in the same plane—because the material was drawn out in a consistent manner
from the Sun.
Historical Importance:
It marked a significant shift from purely mythological explanations to scientific ones. It
encouraged future scientists to explore more plausible models.
Weaknesses and Limitations
Despite its appeal, the Tidal Hypothesis has many weaknesses, which eventually led to its
rejection. Let’s examine them:
1. Extremely Rare Event
• The idea of a massive star passing so close to the Sun is highly improbable. Our
nearest star, Proxima Centauri, is over 4 light years away. For such a close encounter
to occur in a relatively short cosmic timeline is statistically unlikely.
2. Material Would Disperse, Not Condense
• Later studies in physics showed that gases pulled from the Sun would not cool and
clump together easily. Instead, they would likely disperse into space due to low
gravity and high temperature, making it impossible to form planets.
3. Angular Momentum Problem
• The theory fails to account for the distribution of angular momentum in the solar
system. The Sun has 99.8% of the mass, but the planets hold most of the angular
momentum. This mismatch contradicts the idea that the planets came directly from
the Sun’s material.
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4. No Observational Evidence
• Modern astronomical observations have never recorded any evidence of such star-
Sun interactions in nearby stellar systems. It’s purely theoretical.
5. Inconsistent with Planet Sizes
• The planets are too large and diverse to have formed from a uniform tidal stream.
The theory doesn’t explain why the inner planets are rocky and the outer ones are
gaseous.
Rejection and Replacement by Modern Theories
Due to these serious flaws, the Tidal Hypothesis was eventually rejected by the scientific
community. It was replaced by more comprehensive and observationally supported theories
like the:
• Nebular Hypothesis (which suggests that the solar system formed from a rotating
cloud of gas and dust)
• Planetesimal Theory
• Protoplanet Hypothesis
These newer models better explain not just the formation of planets but also the structure,
composition, and motion of the solar system as observed today.
Conclusion: A Stepping Stone in Cosmic Understanding
Although the Tidal Hypothesis is no longer accepted, it remains a significant milestone in the
history of astronomy. It reflects the creative efforts of early 20th-century scientists to
explain the origin of the Earth using available knowledge. The idea of using gravitational
forces, catastrophic events, and stellar interactions inspired a generation of researchers.
Its ultimate failure wasn’t a loss—it was a necessary step that paved the way for better
theories. Just as science evolves by testing and discarding ideas, the Tidal Hypothesis helped
sharpen humanity’s understanding of planetary origins.
2. Discuss the continental drift theory given by Alfred Wegner.
Ans: 1. Background of the Theory
In the early 20th century, geologists believed that continents were fixed and immovable.
The prevailing idea was that the Earth’s features were formed mostly due to vertical
movements, like the rising or sinking of the land.
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However, in 1912, Alfred Wegener challenged this long-held belief by suggesting that
continents are not stationary but have been drifting over geological time. He presented his
detailed ideas in his book "The Origin of Continents and Oceans" published in 1915.
Wegener’s hypothesis was bold and imaginative, and though it wasn’t accepted in his time,
it laid the foundation for modern plate tectonics.
2. The Core Idea of Continental Drift Theory
Wegener proposed that around 200-250 million years ago, all the continents were once
joined together in a single supercontinent known as Pangaea, meaning “all land.” This
supercontinent was surrounded by a massive ocean called Panthalassa.
Over millions of years, Pangaea broke apart, and the pieces drifted slowly in different
directions to form the continents we see today.
He further divided Pangaea into two main parts:
• Laurasia: The northern part (included North America, Europe, and Asia)
• Gondwanaland: The southern part (included South America, Africa, India, Australia,
and Antarctica)
According to Wegener, the continents drifted across the ocean floor, driven by unknown
forces.
3. Evidence Presented by Wegener
Wegener supported his theory with multiple forms of evidence from various fields. Let’s
look at them one by one:
A. Fit of the Continents
• The most striking evidence was the geometric fit between the eastern coast of South
America and the western coast of Africa.
• Wegener argued that this couldn’t be a coincidence and suggested that these
continents were once joined.
B. Fossil Evidence
Identical fossils of ancient plants and animals were found on continents now separated by
oceans.
• Example: Fossils of the Mesosaurus, a freshwater reptile, were found in both South
America and Africa.
• Fossils of Glossopteris, a seed fern, were found in India, South Africa, Australia, and
Antarctica.
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• This suggested that these continents were once connected, allowing organisms to
spread across them.
C. Geological Evidence
Similar rock formations and mountain ranges were found on different continents.
• Example: The Appalachian Mountains in North America are geologically similar to
mountains in Scotland and Norway.
• Also, ancient glacial deposits and striations (scratches made by glaciers) were found
in places that are now warm, like India and South Africa.
• This implied that these areas were once located closer to the South Pole.
D. Paleoclimatic Evidence
Fossils and rock types suggested that the climate of various regions in the past was very
different.
Example: Evidence of tropical swamps in Greenland.
• Glacial evidence in present-day Africa and India.
• This led to the conclusion that continents had shifted their positions, changing their
climates over time.
4. Criticisms and Limitations
Despite all the evidence, Wegener’s theory was not widely accepted in his lifetime. Why?
Main Reason – Lack of Mechanism
Wegener could not explain how the continents moved. He suggested that they might have
ploughed through the ocean floor, pushed by the Earth’s rotation or tidal forces – but these
ideas were scientifically weak.
• Geologists at the time believed that the solid crust of the Earth could not move over
the more rigid ocean floor.
• Because of this, Wegener's theory remained a hypothesis, without enough physical
evidence or mechanism to back it up.
5. Revival of Wegener’s Ideas – Modern Plate Tectonics
In the 1950s and 1960s, new discoveries in oceanography and seismology began to support
Wegener’s ideas.
Key Discoveries:
Mid-ocean ridges: Underwater mountain ranges where new crust is formed, showing that
the seafloor is spreading.
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• Magnetic Stripes: Rocks on the ocean floor showed patterns of magnetic reversal,
proving that new crust was constantly being created and moved.
• Earthquake and volcano patterns: These followed the boundaries of tectonic plates,
not the continents.
• These led to the development of the Plate Tectonics Theory in the 1960s, which
provided the mechanism Wegener’s theory lacked.
6. What is Plate Tectonics? (Brief Overview)
According to plate tectonics:
The Earth’s lithosphere (outer shell) is divided into several large and small plates.
• These plates float on the semi-fluid asthenosphere below and move due to
convection currents in the mantle.
• This movement explains the drift of continents, formation of mountains,
earthquakes, and volcanoes.
• Hence, Wegener’s idea of moving continents was correct, though he couldn’t explain
the "how" part, which plate tectonics later solved.
7. Legacy of Wegener and Importance of the Continental Drift Theory
• Even though Alfred Wegener did not live to see his theory validated (he died in 1930
during an expedition in Greenland), his contribution to Earth science is monumental.
Today, he is celebrated as a visionary who saw the dynamic nature of Earth’s surface
when most others could not.
Significance of Continental Drift Theory:
• It changed how scientists view the Earth’s surface – not as static, but dynamic and
ever-changing.
• It provided a framework for understanding continental formation, ocean basins, and
major geological events.
• It became the stepping stone for the theory of plate tectonics, which is now central
to geology and earth sciences.
8. Conclusion
Alfred Wegener’s Continental Drift Theory was a daring idea born out of careful
observation, deep curiosity, and scientific passion. Though initially rejected due to the lack
of a convincing mechanism, it ultimately transformed into a cornerstone of modern geology
through the development of plate tectonics.
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Wegener’s story teaches us a valuable lesson: Science progresses through challenging old
ideas, asking bold questions, and persistently searching for truth – even when the answers
are not immediately accepted.
SECTION-B
3. What is Fold? Give a detailed account of different kinds of Folds with the help of
suitable diagrams.
Ans: 1. Anticline and Syncline
These are the most common and easily recognizable folds.
Anticline:
• An upward-arching fold.
• The oldest rock layers are at the center.
• Limbs dip away from the axis.
• Think of it like the shape of an “A”.
Syncline:
• A downward-bending fold.
• The youngest rock layers are in the center.
• Limbs dip towards the axis.
• Looks like a “U” or a trough.
• (Insert a diagram showing Anticline and Syncline next to each other)
2. Monocline
A monocline is a simple fold in which rock layers are bent in only one direction.
• Appears like a stair-step.
• Usually formed when horizontal rock layers are pushed upward or downward due to
a fault beneath.
Example: Colorado Plateau in the USA has many monoclines.
(Insert diagram showing one-sided bend in rock layers – Monocline)
3. Symmetrical and Asymmetrical Folds
Symmetrical Fold:
• Both limbs dip at equal angles.
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• The axial plane is vertical.
• Indicates equal pressure from both sides.
Asymmetrical Fold:
• One limb is steeper than the other.
• The axial plane is inclined.
• Suggests more force was applied from one direction.
• (Insert diagram showing a Symmetrical and an Asymmetrical Fold)
4. Overturned and Recumbent Folds
Overturned Fold:
• One limb is tilted beyond vertical, so both limbs dip in the same direction.
• Seen in intensely compressed regions.
Recumbent Fold:
• The fold is nearly horizontal.
• Looks like the fold is lying down or reclining.
• Common in highly deformed mountain regions.
• (Insert diagram showing Overturned and Recumbent Folds)
5. Isoclinal Fold
• In this fold, both limbs are parallel to each other.
• Created due to intense pressure that squeezes the layers into tight parallel bends.
• Common in metamorphic regions.
(Insert diagram of tightly packed, parallel-limbed fold)
6. Chevron Fold
• Sharp, angular fold with V-shaped hinges.
• Layers are of alternating hardness.
• Often found in sedimentary rocks.
• (Insert diagram showing pointed zigzag-shaped Chevron folds)
7. Dome and Basin
Dome:
• Rocks dip outward from a central point.
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• Oldest rocks at the center.
• Resembles an overturned bowl.
• Example: Black Hills, South Dakota.
Basin:
• Rocks dip inward toward a central point.
• Youngest rocks at the center.
• Appears like a bowl or sink.
Example: Michigan Basin.
(Insert simple circular diagram showing dome and basin)
Importance of Studying Folds
Understanding folds is not just an academic exercise – it has real-world significance:
• Natural Resources: Folds often trap oil, gas, and groundwater. Many oil fields lie in
folded rock structures.
• Mountain Building: Most mountain ranges (e.g., Himalayas, Alps) are results of
large-scale folding.
• Earthquake Studies: Folds and faults together help scientists understand seismic
activity.
• Geological Mapping: Helps in knowing the age of rock layers and geological history
of an area.
• Engineering Projects: Large constructions like dams, tunnels, and highways depend
on knowing the fold structure for safety.
Conclusion: The Earth's Wrinkles Tell a Story
Just like wrinkles on an old tree or folds on a crumpled cloth tell us about their history, the
folds in Earth’s crust reveal a grand tale of millions of years of geological drama. They speak
of powerful forces, moving continents, and building mighty mountain chains. By
understanding folds, we uncover secrets of the Earth’s inner workings, and this knowledge
not only satisfies our curio
fold, each formation is a chapter in the Earth's epic story – sity but also guides practical
decisions in energy, infrastructure, and environmental science.
Whether it's the symmetrical grace of an anticline or the dramatic recline of a recumbent
one we are still learning to read.
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1. What is an Earthquake? Discuss the causes behind the occurrence of Earthquake.
Ans: What Causes an Earthquake? (The Main Reasons)
Earthquakes don't just occur randomly. There are scientific causes behind every tremor we
feel. Let’s explore these in detail:
1. Tectonic Plate Movements (Most Common Cause)
The majority of earthquakes in the world are tectonic in origin, meaning they happen due to
the movement of Earth's tectonic plates.
The Earth's lithosphere (crust + upper mantle) is made up of about 7 major plates and many
smaller ones. These plates are constantly moving — albeit very slowly — due to convection
currents in the mantle. When these plates interact, stress builds up. Once the stress exceeds
the strength of rocks at plate boundaries, it releases energy in the form of seismic waves,
causing an earthquake.
There are three main types of plate interactions that cause earthquakes:
• Convergent Boundaries – Two plates collide. One plate may go under another
(subduction), often causing powerful quakes (e.g., earthquakes in Japan).
• Divergent Boundaries – Two plates move apart, and magma rises to fill the gap (e.g.,
the Mid-Atlantic Ridge).
• Transform Boundaries – Plates slide past each other horizontally (e.g., the San
Andreas Fault in California).
2. Volcanic Activity
Another natural cause of earthquakes is volcanic eruptions. These are called volcanic
earthquakes.
When magma rises through the crust to the Earth's surface, it can cause the surrounding
rocks to crack and fracture, producing small to moderate earthquakes. These often occur in
volcanic regions and may act as precursors to an eruption.
For example, before Mount St. Helens erupted in 1980, there were thousands of small
tremors in the region.
3. Faulting and Crustal Stress
A fault is a crack in the Earth's crust where blocks of land have moved past each other.
When stress builds up along these faults and overcomes friction, the rocks suddenly shift,
causing an earthquake.
There are different types of faults:
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• Normal fault – One block moves down.
• Reverse fault – One block moves up.
• Strike-slip fault – Blocks move horizontally past each other.
These movements cause the release of accumulated stress, generating seismic waves that
we feel as earthquakes.
4. Human-Induced Earthquakes (Man-Made Causes)
Humans have also been responsible for triggering earthquakes, especially in modern times.
Though usually smaller, they can still be dangerous.
Some human activities that cause earthquakes include:
• Mining and Quarrying – Blasting rock underground can sometimes disturb fault
lines.
• Reservoir-Induced Seismicity – Building large dams and reservoirs (like the Koyna
Dam in India) creates huge water pressure, which can seep into rocks and trigger
seismic activity.
• Oil and Gas Extraction – Fracking and deep drilling alter underground pressure and
cause minor quakes.
• Nuclear Tests – Underground nuclear explosions have been known to trigger
earthquakes.
5. Isostatic Rebound and Earthquakes
After heavy glaciers melt, the Earth’s crust begins to rebound or rise back to its original
position. This slow rebound process can also cause faults to reactivate and result in small
earthquakes. This is called isostatic adjustment.
6. Elastic Rebound Theory
This theory explains how tectonic earthquakes occur. Imagine two blocks of rock on either
side of a fault. As tectonic forces push them, they bend and store energy. Eventually, the
stress becomes too much, and they suddenly slip, releasing energy — causing an
earthquake. After the slip, the rocks return to their original shape but in a new position. This
sudden 'rebound' is what we experience during a quake.
Famous Earthquake Zones of the World
Earthquakes can technically occur anywhere, but some regions are more prone to them.
These areas lie along fault lines and tectonic boundaries.
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• The Ring of Fire – Encircles the Pacific Ocean; includes Japan, Indonesia, California,
Chile.
• The Himalayan Belt – Includes Nepal, Northern India, Pakistan.
• The Mid-Atlantic Ridge – A divergent boundary under the Atlantic Ocean.
• East African Rift Valley – A divergent plate boundary in Africa.
How Are Earthquakes Measured?
• Richter Scale – Measures the magnitude (energy released) of an earthquake. Scale
goes from 0 to 10+.
• Below 4.0 – Minor
• 4.0–6.0 – Moderate
• 6.0–7.0 – Strong
• Above 7.0 – Major
Mercalli Scale – Measures intensity, i.e., how the earthquake felt and what damage it
caused.
Seismograph – The instrument that records earthquake waves is called a seismograph. It
draws a graph called a seismogram.
Effects of Earthquakes
• Ground shaking and ruptures
• Damage to buildings, roads, and infrastructure
• Landslides and avalanches
• Tsunamis (in coastal areas)
• Fires (due to gas leaks or electrical failures)
• Economic losses and psychological trauma
Earthquake Preparedness and Safety
• Since we cannot prevent earthquakes, preparedness is key:
• Building earthquake-resistant structures
• Conducting earthquake drills
• Having emergency kits ready
• Staying away from glass windows and tall furniture during tremors
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Conclusion
Earthquakes are one of the most powerful forces of nature. Though they often come
without warning, their causes are deeply rooted in the Earth’s natural processes — primarily
tectonic activity, volcanic movements, and sometimes human interference. As students and
citizens of a vulnerable planet, it is important to understand how and why earthquakes
occur so that we can be better prepared and more respectful of the powerful natural
systems that govern our world.
The next time you feel the ground shake, remember: it's the Earth, telling us its age-old
story — one written in rocks, faults, and tectonic movements beneath our feet.
SECTION-C
5. What is a Rock? Give a detailed account of igneous rocks.
Ans: What are Igneous Rocks?
Let us start the journey from the very beginning — deep inside the Earth.
Underneath the Earth's crust, temperatures and pressures are so high that rocks melt and
form magma, a molten material composed of minerals, gases, and water vapor. When this
hot magma cools and solidifies, it becomes what we call an igneous rock. So, the name
“igneous” is derived from the Latin word “ignis”, meaning fire.
Thus, igneous rocks are formed by the cooling and solidification of molten magma or lava.
If the magma cools inside the Earth’s crust, the rocks formed are called intrusive or plutonic
igneous rocks.
If the magma reaches the Earth’s surface through volcanic activity and cools down there,
the rocks formed are called extrusive or volcanic igneous rocks.
Types of Igneous Rocks
1. Intrusive (Plutonic) Igneous Rocks
These are formed when magma cools slowly beneath the Earth's surface. Because of the
slow cooling, large crystals have time to form, giving the rock a coarse-grained texture.
Examples:
• Granite – Light-colored, contains quartz, feldspar, and mica. Used in buildings and
monuments.
• Diorite – Contains plagioclase feldspar and hornblende.
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• Gabbro – Dark-colored, made of pyroxene and plagioclase.
Characteristics:
• Coarse-grained texture (large crystals)
• Found deep inside the Earth's crust
• Strong and durable
2. Extrusive (Volcanic) Igneous Rocks
These are formed when lava (magma that reaches the surface) cools quickly on the Earth’s
surface. Due to rapid cooling, crystals do not have much time to grow, so the rocks are fine-
grained or even glassy.
Examples:
• Basalt – Dark, fine-grained, and the most common volcanic rock. Ocean floors are
mostly basalt.
• Rhyolite – Light-colored and fine-grained.
• Obsidian – Glassy, black, shiny, formed from lava that cooled extremely quickly.
• Pumice – Frothy appearance, very light and porous, often floats on water.
Characteristics:
• Fine-grained or glassy texture
• Formed on the surface from lava
• Often have air holes (vesicles) due to trapped gases
Textures of Igneous Rocks
The texture of an igneous rock gives us clues about its cooling history:
Texture
Description
Example
Coarse-Grained
Large crystals, slow cooling
Granite, Gabbro
Fine-Grained
Small crystals, quick cooling
Basalt, Rhyolite
Glassy
No crystals, extremely fast cooling
Obsidian
Porphyritic
Large crystals embedded in a fine-grained matrix
Andesite
Vesicular
Contains air holes from gas bubbles
Pumice, Scoria
Distribution of Igneous Rocks
Igneous rocks are found all over the world, especially in regions with volcanic activity and
tectonic movement.
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• Basalt is the most abundant rock on Earth’s surface, particularly found in ocean
floors and volcanic islands like Hawaii.
• Granite forms the core of many continental masses, especially in mountain ranges.
Mineral Composition of Igneous Rocks
Igneous rocks can be classified based on their mineral content:
1. Felsic Rocks
• Rich in silica, light-colored
• Main minerals: quartz, feldspar
• Example: Granite, Rhyolite
2. Mafic Rocks
• Low in silica, rich in magnesium and iron, dark-colored
• Main minerals: pyroxene, olivine
Example: Basalt, Gabbro
3. Intermediate Rocks
Between felsic and mafic in composition
Example: Diorite, Andesite
Significance of Igneous Rocks
Igneous rocks play a critical role in geology and human life:
1. Foundation of Continents
They form the base of the continental crust. Many mountain chains are made of igneous
rocks.
2. Economic Importance
Granite is used in construction and monuments.
Pumice is used in polishes, toothpaste, and scrubs.
Obsidian was used in ancient times for making sharp tools.
Valuable minerals like gold, silver, copper, and diamonds are found in igneous rocks.
3. Soil Formation
When igneous rocks weather and break down, they form mineral-rich soils, which are good
for agriculture, especially basalt-derived black soil.
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4. Clues About Earth’s Interior
Since these rocks originate from magma, they give geologists valuable information about
the composition of Earth’s interior, tectonic activity, and volcanic processes.
Conclusion: Why Study Igneous Rocks?
In the grand story of Earth’s history, igneous rocks are the storytellers of fire. They speak of
ancient volcanoes, the movement of continents, and the creation of landscapes. Whether
lying deep in the Earth or scattered across a field, these rocks are witnesses to powerful
natural processes.
For university students, understanding igneous rocks is more than memorizing names — it’s
about developing the skill to read the planet’s history, to recognize where resources come
from, and to appreciate the powerful forces that shaped our world. In geology, this is a
foundational step — just as granite forms the foundation of mountains, so too does
knowledge of igneous rocks form the base for deeper geological learning.
6. Define a Plateau. Discuss the different types of plateaus with help of suitable examples.
Ans: What is a Plateau?
A plateau is a broad, flat-topped region that stands elevated from the surrounding area. It
can be thought of as a "tableland" — flat like a table but raised above the ground.
Definition:
A plateau is an area of highland, usually consisting of relatively flat terrain that is elevated
significantly above the surrounding area on at least one side.
Plateaus can be found on every continent and take up almost one-third of the Earth's land
surface.
How Do Plateaus Form?
The formation of a plateau is often a result of geological forces such as:
Tectonic uplift (when sections of the Earth’s crust are pushed upward),
Volcanic activity (lava flows creating layers),
Or even erosion (where surrounding areas are worn down, leaving a higher flat surface).
These geological processes take thousands or even millions of years, shaping the Earth
slowly and steadily.
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Characteristics of a Plateau:
• Elevated landform: Higher than the surrounding areas.
• Flat or gently rolling surface: Unlike the rugged peaks of mountains.
• Steep sides or escarpments: Often have abrupt slopes.
• Different climates and vegetation: Depending on location and height.
Types of Plateaus:
Plateaus can be broadly classified into five main types based on how they were formed:
1. Intermontane Plateau:
Let’s begin with a type that lives between mountains.
Definition:
An intermontane plateau is a plateau that is located between two or more mountain ranges.
These are some of the highest and largest plateaus in the world.
Example:
Tibetan Plateau — Called the “Roof of the World”, it lies between the Himalayas in the
south and the Kunlun Mountains in the north.
It is the world’s highest and largest plateau, averaging 4,500 meters above sea level.
Formed due to the collision of the Indian and Eurasian tectonic plates.
Features:
• High elevation
• Surrounded by high mountains
• Cold and dry climate
• Sparse vegetation and population
2. Volcanic Plateau:
Now imagine volcanoes not just exploding, but spreading lava that cools and hardens over
time, forming layers.
Definition:
A volcanic plateau is formed when lava from volcanic eruptions flows over large areas and
solidifies, forming a flat, elevated surface.
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Examples:
• Deccan Plateau in India:
• Covers most of South India.
• Formed millions of years ago due to volcanic eruptions.
• Rich in black soil, ideal for cotton farming.
Columbia Plateau in the USA:
Formed by massive lava flows in Washington, Oregon, and Idaho.
Features:
• Layers of solidified lava
• Fertile soil (due to minerals from lava)
• Flat or gently rolling terrain
3. Tectonic Plateau:
• Let’s revisit the deep movements of the Earth again.
Definition:
• A tectonic plateau is formed when Earth’s crust is uplifted due to internal forces or
movements of tectonic plates.
• Unlike volcanic plateaus, these are not formed by lava but by earth movements.
Examples:
• Tibetan Plateau (also fits here due to tectonic collision)
Colorado Plateau in the USA:
• Uplifted during tectonic activities.
• Home to the Grand Canyon, which was later carved by the Colorado River.
Features:
• High elevation
• May contain mountains or deep valleys (if rivers cut through)
• May experience earthquakes
4. Erosional Plateau:
Sometimes nature carves away the surroundings, leaving behind highlands.
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Definition:
An erosional plateau is formed by the erosion of surrounding land, leaving a flat-topped
highland.
Example:
• Ozark Plateau in the USA.
• Chotanagpur Plateau in India (partly erosional).
• Located in Jharkhand and adjoining states.
• Formed by weathering and erosion over time.
Features:
• Rich in minerals (especially in India)
• Older landforms
• Less rugged, more worn-down
5. Dissected Plateau:
Think of a flat land being cut by rivers over centuries. It still remains elevated but becomes
rugged and uneven.
Definition:
A dissected plateau is one where rivers and streams have eroded the land surface, creating
valleys and hills but retaining the plateau’s elevated status.
Examples:
• Chotanagpur Plateau (again, fits here too).
• Appalachian Plateau in the USA.
Features:
• Deep valleys, gorges, and hills
• Good river systems
Important for agriculture and mining
Importance of Plateaus:
• Rich in Minerals: Many plateaus are mineral-rich and serve as mining hubs (e.g.,
Chotanagpur Plateau in India is rich in coal, iron, mica).
• Agriculture: Volcanic plateaus have fertile soils (e.g., Deccan Plateau).
• Water Resources: Rivers originating from plateaus are used for irrigation and
hydroelectricity.
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• Forests and Wildlife: Many plateaus are covered with forests and are home to
diverse fauna and flora.
• Human Settlements: Due to moderate climate and flat terrain, plateaus support
settlements.
Conclusion:
Plateaus are not just landforms; they are natural wonders that reveal Earth's history — from
fiery volcanic eruptions to the slow dance of tectonic plates, and from the carving hand of
erosion to the silence of high-altitude plains. Each plateau, whether it's the lofty Tibetan
Plateau or the culturally rich Deccan Plateau, has its unique origin story, ecological value,
and economic importance.
For university students, understanding plateaus is like reading a chapter from Earth’s own
diary. These elevated tablelands have influenced civilizations, weather patterns, and
resource distribution across continents. The next time you walk on a plateau or read about
one, remember — you're standing on a platform shaped by the forces of deep time and
mighty geology.
SECTION-D
7. Discuss the work of wind as an agent of Denudation.
Ans: Wind as an Agent of Denudation
Wind works like a sculptor in deserts, constantly blowing sand and dust, carving and shaping
the landforms. It acts through the following three main processes:
1. Erosion by Wind
Erosion by wind happens mainly in dry and loose soil areas. There are two main methods by
which wind erodes land:
(a) Deflation
Deflation is the process of lifting and removing loose particles such as fine sand and dust
from the land surface. Think of it like a vacuum cleaner sucking up tiny particles.
• Over time, continuous deflation can lead to the formation of deflation hollows –
shallow depressions created by the removal of finer material.
• If this process continues, these hollows may join and form larger basins.
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Example: Many parts of the Sahara Desert have deflation hollows that were once flat but
are now shallow basins.
(b) Abrasion
Abrasion is the sandblasting effect of wind. It occurs when wind-blown sand particles hit
against rock surfaces. Just like sandpaper, the wind grinds and polishes the surfaces, slowly
wearing them down.
• It mainly affects rocks at lower levels (closer to the ground).
• Windblown sand can carve out unique shapes in rocks.
Example: The mushroom-shaped rocks found in deserts are a result of wind abrasion — the
lower part of the rock gets eroded more than the upper part due to direct impact by flying
sand.
Landforms Created by Wind Erosion
As wind erodes the surface, it creates several unique and fascinating landforms. Let’s
explore them:
1. Deflation Hollows and Basins
As already explained, when wind removes fine particles from a region over time, it can
create a shallow depression. These are common in deserts.
2. Yardangs
These are streamlined ridges of rock, carved by wind erosion. They are aligned in the
direction of the wind flow.
• Softer rock erodes faster, leaving behind ridges of harder rock.
• They look like boat hulls turned upside down.
Example: Yardangs are commonly found in the deserts of Egypt and Central Asia.
3. Mushroom Rocks (Pedestal Rocks)
• These are rock formations with a narrow base and wider top, resembling a
mushroom.
• The lower portion gets more erosion due to closer contact with blowing sand.
• The top remains relatively untouched.
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4. Zeugen
Zeugen are long, tabular ridges formed when wind erodes alternating layers of hard and soft
rock. Over time, the softer layers get removed, leaving the hard rock standing like a table.
Transportation by Wind
Once the wind has eroded and picked up loose particles, it carries them across distances.
The process of transportation depends on the size of the particles and the speed of the
wind.
Wind transports materials in three main ways:
• Suspension – Fine dust and clay particles are lifted and carried in the air for long
distances.
• Saltation – Medium-sized particles like sand bounce or hop along the surface.
• Surface Creep – Larger particles roll along the ground due to wind pressure.
These transported particles eventually settle down when the wind loses its energy — this
leads to deposition.
Landforms Created by Wind Deposition
Wind not only erodes and transports materials but also drops them when its speed
decreases. This forms several deposition-based landforms:
1. Sand Dunes
These are mounds or hills of sand formed when wind deposits sand in one place.
• Dunes can take many shapes like barchans (crescent-shaped), seif dunes (long
ridges), and star dunes.
• They are common in deserts like the Thar Desert, Sahara, and Rub' al Khali.
2. Loess Deposits
Loess refers to fine silt and clay particles deposited by wind over large areas.
• These are fertile and good for agriculture.
• Major loess regions include China, parts of Europe, and North America.
Why is Wind More Active in Deserts?
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Wind becomes a dominant agent of denudation in deserts due to several factors:
• Lack of Vegetation: No plants to hold the soil in place.
• Loose, Dry Soil: Easy for wind to pick up and carry.
• High Temperature: Causes rapid weathering and drying of surfaces.
• Open Terrain: Fewer obstacles allow wind to blow freely.
Positive and Negative Effects of Wind Erosion
Like every force of nature, wind erosion has both good and bad sides:
Positive Effects:
• Formation of fertile loess plains.
• Creation of unique desert landforms that are tourist attractions.
Negative Effects:
• Desertification – Spread of desert-like conditions into fertile areas.
• Loss of topsoil – Harms agriculture.
• Dust storms – Dangerous for health and environment.
Conclusion
Wind may seem soft and gentle, but over time, it acts as a powerful force shaping the
Earth’s surface — especially in dry, barren lands. Through the processes of deflation,
abrasion, transportation, and deposition, wind contributes greatly to denudation.
Its sculpting hands have carved mushroom rocks, swept away sands to form dunes, and
even created vast stretches of fertile loess plains. Understanding the work of wind not only
reveals nature’s artistic genius but also teaches us the importance of managing land and
vegetation to prevent soil loss.
So, next time you feel a strong breeze brushing against your face, remember — that same
force has shaped deserts, created landscapes, and changed the Earth for millions of years!
8. Discuss the application of Geomorphology in the human activities.
Ans: 1. Urban Planning and Construction
Imagine building a city on a steep hill that is prone to landslides. That would be a disaster waiting to
happen. This is where geomorphology helps urban planners and engineers. Before any infrastructure
— roads, buildings, dams, or bridges — is developed, the geomorphological nature of the land must
be understood.
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Applications:
• Identifying stable land for construction
• Avoiding flood-prone or landslide-prone areas
• Planning drainage systems based on the slope and soil structure
• Earthquake-prone areas are mapped through tectonic geomorphology
Example: In cities like Shimla or Gangtok in India, special attention is given to slope stability before
any construction due to the risk of landslides.
2. Agriculture and Soil Use
The fertility of land, water availability, and the slope of the terrain determine what kind of crops can
be grown. Geomorphology helps farmers and agricultural planners to identify:
• Best locations for farming
• Soil types and erosion patterns
• Terrace farming suitability in hilly regions
• Water retention capacity of soil
Example: The Indo-Gangetic plain is highly fertile due to alluvial deposits. This has been recognized
through geomorphological studies and supports one of the largest agricultural belts in the world.
3. Water Resource Management
Water is life — and geomorphology plays a key role in managing and conserving water resources.
Rivers, lakes, groundwater levels, and drainage basins are studied through geomorphology.
Applications:
• Identifying sites for dam construction
• Floodplain mapping to prevent disasters
• Understanding river meandering to protect infrastructure
• Assessing groundwater recharge zones
Example: The Ganga-Brahmaputra delta, which faces seasonal floods, is studied extensively using
geomorphological tools to plan embankments and flood control systems.
4. Transportation and Infrastructure Development
Transportation routes like roads, highways, and railway lines need flat, stable, and cost-effective
paths. Geomorphological analysis helps identify:
• The best routes avoiding high-risk zones (e.g., landslides, marshlands)
• Locations for bridges, tunnels, and cuttings
• Risk zones for erosion or land subsidence
Example: In the Western Ghats, railway tracks and roads are laid with the help of geomorphologists
to avoid monsoon-related soil erosion and landslides.
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5. Mining and Natural Resource Exploration
Minerals, fossil fuels, and construction materials like limestone or gravel are buried in the Earth.
Geomorphology helps locate and extract these without damaging the environment.
Applications:
• Mapping mineral-rich areas
• Understanding landform evolution for oil exploration
• Site suitability for open-pit vs underground mining
Example: Plateau regions like the Deccan Plateau have rich mineral resources. Geomorphologists
help locate coal seams and iron deposits in Jharkhand and Odisha.
6. Disaster Management and Mitigation
Natural disasters like earthquakes, floods, landslides, and tsunamis have geomorphological origins.
By studying landforms, geomorphologists can help reduce the impact of such disasters.
Applications:
• Earthquake zoning maps
• Landslide risk assessments
• Flood forecasting and floodplain zoning
• Tsunami-prone coastline mapping
Example: The Himalayan region is earthquake-prone. Construction codes and disaster preparedness
plans in states like Uttarakhand and Himachal Pradesh are based on geomorphological risk zones.
7. Tourism and Recreation
Many tourist attractions are based on natural landforms — mountains, waterfalls, valleys,
beaches. Understanding geomorphology allows for:
• Sustainable development of tourism spots
• Managing footfall to avoid erosion and degradation
• Conservation of natural heritage
Example: The backwaters of Kerala, the sand dunes of Rajasthan, and the glacial valleys in Kashmir
are all studied and preserved through geomorphological planning.
8. Archaeological and Historical Studies
Geomorphology also helps in understanding ancient human settlements. Civilizations often
developed along rivers, fertile plains, or natural shelters. Geomorphologists work with
archaeologists to study:
• Changes in river courses (like the lost Saraswati river)
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• Ancient flood patterns and climate change
• Site selection and preservation of heritage monuments
Example: The Harappan civilization developed on the banks of ancient rivers. Geomorphological
mapping helped locate buried towns like Dholavira and Kalibangan.
9. Environmental Conservation and Climate Change
As the Earth warms and climate changes, landforms are also changing — glaciers are melting, coasts
are eroding, deserts are expanding. Geomorphologists help:
• Monitor coastal erosion and retreat
• Predict glacier melting impacts on river systems
• Rehabilitate degraded land
Example: In Ladakh, geomorphologists study glacier retreat to understand water shortages in
villages that depend on glacial melt.
Conclusion: Why Geomorphology Matters to Us
So, the next time you travel through mountains, cross a river, or walk along a beach — remember,
you are not just seeing beauty but living on a landscape shaped by thousands of years of geological
processes. Geomorphology is the silent guide helping humans adapt, plan, and survive on this
dynamic planet.
Whether it's farming, building, conserving, or exploring — geomorphology touches almost every
aspect of human life. Its applications go beyond textbooks and classrooms — it is truly the science of
living with the land.
For University Students: Key Takeaways
• Geomorphology is not just theoretical – it has real-life applications.
• It helps in planning cities, managing disasters, building roads, farming, and more.
• Understanding the land helps us avoid future risks and make sustainable choices.
• Fields like civil engineering, urban planning, agriculture, disaster management, and tourism
all use geomorphological insights.
“This paper has been carefully prepared for educational purposes. If you notice any mistakes or
have suggestions, feel free to share your feedback.”
