Shaping of the Earth’s Surface Class 9 Worksheet with Answers SST Chapter 2

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Shaping of the Earth’s Surface Worksheet Class 9

Class 9 Shaping of the Earth’s Surface Worksheet

Worksheet On Shaping of the Earth’s Surface Class 9

Multiple Choice Questions

Question 1.
The theory of Plate Tectonics, which explains the slow movement of the Earth’s crustal plates over the mantle, was formulated by which of the following scientists?
(a) Alfred Wegener
(b) W.J. Morgan
(c) Harry Hess
(d) Arthur Holmes
Answer:
(b) W.J. Morgan

Question 2.
Consider the following case and choose the correct option.
A student claims that tectonic plates are fixed and do not move, and that the Earth’s surface remains unchanged over time. Based on the concept of lithosphere and asthenosphere, what is the correct understanding?
(a) Yes, because the lithosphere is completely rigid and does not allow any movement.
(b) No, because tectonic plates are massive slabs of rock that move slowly over the semi-molten asthenosphere,
(c) Yes, because only the mantle moves, not the crust or plates.
(d) No, because the asthenosphere is solid and prevents plate movement.
Answer:
(b) No, because tectonic plates are massive slabs of rock that move slowly over the semi-molten asthenosphere,

Question 3.
Which one of the following pairs is correctly matched?
(a) Continental crust – 5-7 km thick
(b) Oceanic crust – 30-40 km thick
(c) Oceanic crust – 5-7 km thick
(d) Continental crust – 100 km thick
Answer:
(c) Oceanic crust – 5-7 km thick

Question 4.
Find the odd one out from the following.
(a) Inner Core
(b) Asthenosphere
(c) Outer Core
(d) Lithosphere
Answer:
(b) Asthenosphere

Question 5.
Identify the term with the help of the following information.
• It is the rigid outer layer of the Earth.
• It consists of the crust and the uppermost mantle.
• It is broken into tectonic plates.

(a) Asthenosphere
(b) Lithosphere
(c) Mantle
(d) Outer Core
Answer:
(b) Lithosphere

Question 6.
Which of the following plate boundaries is characterised by plates sliding horizontally past each other without creating or destroying the crust, such as along the San Andreas Fault?
(a) Convergent Boundary
(b) Divergent Boundary
(c) Transform Boundary
(d) Subduction Zone
Answer:
(c) Transform Boundary

Question 7.
The primary engine driving the continuous lateral movement of massive tectonic plates across the globe is Competency.
(a) The gravitational pull of the moon acting on tectonic boundaries
(b) Convection currents in the mantle powered by interior radioactive and thermal energy!
(c) Frictional heating generated by the spinning of the inner metal core
(d) Centrifugal force generated by the Earth’s diurnal rotation
Answer:
(b) Convection currents in the mantle powered by interior radioactive and thermal energy!

Question 8.
The mud volcano at Baratang Island in the Andaman and Nicobar Islands is a unique natural feature where mud, instead of lava, erupts due to underground gases and pressure. Over time, nearby rocks are broken down into smaller pieces by changes in temperature, water, and other natural processes without being transported from their original place.

Which of the following processes is taking place in the rocks?
(a) Weathering, because the rocks are broken into smaller pieces without being moved.
(b) Erosion, because the broken rocks remain at the same place.
(c) Deposition, because sediments are being laid down at the same location.
(d) Volcanism, because all rock breaking is caused by volcanic eruptions.
Answer:
(a) Weathering, because the rocks are broken into smaller pieces without being moved.

Question 9.
Arrange the following stages in the correct sequence and choose the correct option.
I. Transportation of sediments
II. Weathering of rocks
III. Deposition of sediments
IV. Erosion by natural agents

Options
(a) II, IV, I, III
(b) IV, II, I, III
(C) II, I, IV, III
(d) III, II, IV, I
Answer:
(a) II, IV, I, III

Question 10.
Identify the appropriate option to fill in the empty boxes.

Types of Erosion

Water Erosion	?	?
Caused by rivers, rain, or ocean waves.	Common in dry and sandy areas.	Where moving ice scrapes and carries rocks.

(a) Wind erosion, Glacial erosion
(b) Glacial erosion, Wind erosion
(c) Weathering, Wind erosion
(d) Deposition, Glacial erosion
Answer:
(a) Wind erosion, Glacial erosion

Question 11.
Consider the following statements regarding weathering and choose the correct option.
(i) Weathering breaks down rocks on the Earth’s surface into smaller fragments.
(ii) Weathering requires the physical transportation of broken materials to distant locations by wind or water.
(a) Only (i) is correct.
(b) Only (ii) is correct.
(c) Both (i) and (ii) are correct.
(d) Neither (i) nor (ii) is correct.
Answer:
(a) Only (i) is correct.

Question 12.
Earthen embankments built along contour lines of a hillside to slow surface run-off, reduce soil erosion, and increase water infiltration are called.
(a) Contours
(b) Bunds
(c) Terraces
(d) Deltas
Answer:
(b) Bunds

Question 13.
The ancient irrigation dam called Grand Anicut (Kallanai) in Tamil Nadu represents a historic human adaptation to which type of running water feature?
(a) Glacial Moraine
(b) Coastal Wave Cliff
(c) River Meander
(d) Limestone Sinkhole
Answer:
(c) River Meander

Question 14.
Choose the correct option to fill in the blank.

Options
(a) Delta
(b) Coastal Erosion
(c) Glacier
(d) Sand dune
Answer:
(b) Coastal Erosion

Question 15.
Read the given infographic carefully and choose the correct option that identifies the landform described.

Options
(a) Plateau II
(b) Beach
(c) Valley
(d) Gorge
Answer:
(b) Beach

Question 16.
If two distinct glaciers merge in a high-altitude mountain valley, which deposit is most likely to form down the central axis of the combined glacial flow?
(a) Lateral Moraine
(b) Medial (Mid) Moraine
(c) Terminal Moraine
(d) Yardang Ridge
Answer:
(b) Medial (Mid) Moraine

Question 17.
An agricultural community in a dry, sandy desert observes that the wind is systematically eroding fine sand grains, leaving behind a hard, flat surface consisting solely of interlocking gravels and pebbles. This newly exposed geologic feature is known as a
(a) Deflation Hollow
(b) Yardang
(c) Desert Pavement
(d) Star Dune
Answer:
(c) Desert Pavement

Question 18.
In a limestone region experiencing high rainfall, water mixes with carbon dioxide to form a weak acid. This acidic water leaks down joint cracks, dissolving the rock over thousands of years. If a large underground cavern is formed, and its roof suddenly collapses due to gravity, which land form is created directly at the surface?
(a) Stalagmite
(b) Sinkhole (Doline)
(c) Wave-cut Platform
(d) Oxbow Lake
Answer:
(b) Sinkhole (Doline)

Assertion-Reason Questions

Directions (Question Nos. 19-25)In the following questions, a statement of Assertion (A) is followed by a statement of Reason (R), Choose the correct option from the choices given below.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.

Question 1.
Assertion (A) Fold mountains like the Himalayas are formed at convergent plate boundaries.
Reason (R) When two continental plates collide, the immense compressive force buckles and folds the rock layers upwards.
Answer:
(a) Both A and R are true and R is the correct explanation of A.

Question 2.
Assertion (A) The region surrounding the Pacific Ocean is highly vulnerable to devastating volcanic eruptions and earthquakes.
Reason (R) The “Ring of Fire” corresponds to active subduction zones and tectonic plate boundaries along the Pacific Plate margins.
Answer:
(a) Both A and R are true and R is the correct explanation of A.

Question 3.
Assertion (A) In his ancient treatise Brihatsamhita, the scholar Varahamihira dedicated an entire section to predicting earthquakes (bhukampa).
Reason (R) Varahamihira possessed modern seismographs and GPS equipment to track active fault slip lines across India.
Answer:
(c) A is true, but R is false.

Question 4.
Assertion (A) River deltas are typically densely populated and serve as thriving economic and agricultural hubs.
Reason (R) The continuous deposition of nutrient-rich alluvial soils at the river mouth makes deltas exceptionally fertile and highly productive for crops like rice and jute.
Answer:
(a) Both A and R are true and R is the correct explanation of A.

Question 5.
Assertion (A) Sea stacks are isolated vertical pillars of rock standing in the ocean near steep coastlines.
Reason (R) They are formed when sea waves systematically deposit layers of wind-blown desert sand along wave-cut platforms.
Answer:
(a) Both A and R are true and R is the correct explanation of A.

Question 6.
Assertion (A) Deforestation significantly increases the hazard of massive landslides on steep mountain slopes during heavy rainstorms. Reason (R) Tree roots act as natural binders that physically anchor the soil and stabilise slope structures against gravity.
Answer:
(a) Both A and R are true and R is the correct explanation of A.

Question 7.
Assertion (A) Glacial Lake Outburst Floods (GLOFs) present a major hazard to hydropower projects and human settlements located downstream.
Reason (R) Rising global temperatures accelerate glacial melting, increasing the water volume in lakes dammed by fragile, loose moraines until the dams burst.
Answer:
(a) Both A and R are true and R is the correct explanation of A.

Match the Columns

Question 1.
Match Column 1 with Column II.

Column I (Tectonic Process)	Column II (Geological Feature / Example)
A. Convergent Boundary Collision	1. Mid-Atlantic Ridge
B. Divergent Boundary Seafloor Spreading	2. San Andreas Fault
C. Transform Slip	3. The Himalaya
D. Plate Boundaries	4. Edges where tectonic plates meet

Options
(a) A – 3, B – 2, C – 1, D – 4
(b) A – 2, B – 3, C – 4, D – 1
(c) A – 1, B – 4, C – 2, D – 3
(d) A – 3, B – 1, C – 2, D – 4
Answer:

Column I (Tectonic Process)	Column II (Geological Feature / Example)
A. Convergent Boundary Collision	3. The Himalaya
B. Divergent Boundary Seafloor Spreading	1. Mid-Atlantic Ridge
C. Transform Slip	2. San Andreas Fault
D. Plate Boundaries	4. Edges where tectonic plates meet

Question 2.
Match Column I with Column II.

Column I (System)	Column II (Description of Technique)
A. Zabo System	1. Digging trenches along equal elevation lines to slow rainwater infiltration
B. Contour Trenching	2. Integrated hill farming in Nagaland using earthen bunds and check dams
C. Bunding	3. Earthen embankments built along contour lines to reduce soil erosion

Options
(a) A – 2, B – 1, C – 3
(b) A – 3, B – 2, C – 1
(c) A – 1, B – 3, C – 2
(d) A – 1, B – 2, C – 3
Answer:

Column I (System)	Column II (Description of Technique)
A. Zabo System	2. Integrated hill farming in Nagaland using earthen bunds and check dams
B. Contour Trenching	1. Digging trenches along equal elevation lines to slow rainwater infiltration
C. Bunding	3. Earthen embankments built along contour lines to reduce soil erosion

Question 3.
Match Column I with Column II.

Column I (Course of the River)	Column II (Primary Characteristic Landforms)
A. Upper Course	1. Meanders, Oxbow Lakes, Floodplains
B. Middle Course	2. Fan-shaped Alluvial Deltas, Levees
C. Lower Course	3. Steep V-shaped Valleys, Waterfalls, Rapids
D. River Mouth	4. Deposition of sediments into a sea or lake

Options
(a) A – 3, B – 1, C – 2, D – 4
(b) A – 2, B – 3, C – 4, D – 1
(c) A – 1, B – 2, C – 3, D – 4
(d) A – 4, B – 1, C – 2, D – 3
Answer:

Column I (Course of the River)	Column II (Primary Characteristic Landforms)
A. Upper Course	3. Steep V-shaped Valleys, Waterfalls, Rapids
B. Middle Course	1. Meanders, Oxbow Lakes, Floodplains
C. Lower Course	2. Fan-shaped Alluvial Deltas, Levees
D. River Mouth	4. Deposition of sediments into a sea or lake

Question 4
Match Column I with Column II.

Column I (Coastal Feature)	Column II (Erosional or Depositional Origin)
A. Sea Stack	1. Erosional hollow formed at the base of a sea cliff by wave action
B. Beach	2. Opening formed when waves erode through a headland
C. Sea Cave	3. Depositional feature consisting of sand or pebbles along the shoreline
D. Sea Arch	4. Erosional feature formed when a sea arch collapses

Options
(a) A – 4, B – 3, C – 1, D – 2
(b) A – 2, B -1, C – 4, D – 3
(c) A – 1, B – 2, C – 3, D – 4
(d) A – 3, B – 4, C – 2, D -1
Answer:

Column I (Coastal Feature)	Column II (Erosional or Depositional Origin)
A. Sea Stack	4. Erosional feature formed when a sea arch collapses
B. Beach	3. Depositional feature consisting of sand or pebbles along the shoreline
C. Sea Cave	1. Erosional hollow formed at the base of a sea cliff by wave action
D. Sea Arch	2. Opening formed when waves erode through a headland

Question 5.
Match Column I with Column II.

Column I (Desert Feature)	Column II (Formative Process/Shape)
A. Barchan Dune	1. Depression formed by wind deflation that reaches the water table
B. Yardang	2. Crescent-shaped sand mound pointing in the direction of wind flow
C. Oasis	3. Streamlined, narrow rock ridge carved by wind erosion
D. Desert Pavement	4. Surface covered with pebbles and gravels left after fine particles are removed by wind

Options
(a) A – 2, B – 3, C – 1, D – 4
(b) A – 3, B – 4, C – 2, D – 1
(c) A – 1, B – 2, C – 4, D – 3
(d) A – 4, B – 1, C – 3, D – 2
Answer:

Column I (Desert Feature)	Column II (Formative Process/Shape)
A. Barchan Dune	2. Crescent-shaped sand mound pointing in the direction of wind flow
B. Yardang	3. Streamlined, narrow rock ridge carved by wind erosion
C. Oasis	1. Depression formed by wind deflation that reaches the water table
D. Desert Pavement	4. Surface covered with pebbles and gravels left after fine particles are removed by wind

Picture-Based Questions

Question 1.
Based on the schematic diagram of the Earth’s interior, what is the approximate combined thickness of the lithosphere and the asthenosphere, and which of these layers contains the crust?

(a) 300 km; the asthenosphere contains the crust.
(b) 300 km; the lithosphere contains the crust.
(c) 2100 km; the lithosphere contains the crust.
(d) 100 km; both layers contain the crust.
Answer:
(b) 300 km; the lithosphere contains the crust.

Question 2.
Refer to the heat transport mechanism inside the Earth’s layers in the given figure. Which layer accounts for the highest individual percentage of total interior heat flow, and what is its primary heat transport mechanism shown by the circular arrows?

(a) Crust (24%); Conduction
(b) Core (22%); Radiation
(c) Upper Mantle (22%); Advection
(d) Lower Mantle (32%); Convection
Answer:
(d) Lower Mantle (32%); Convection

Question 3.
Study the given figure carefully and answer the following questions.

(a) Name the landform formed at the base of a waterfall.
Answer:
The landform formed at the base of a waterfall is a Plunge Pool.

(b) Explain how this landform is formed.
Answer:
It is formed due to the continuous erosion caused by the falling water at the base of the waterfall.

Very Short Answer Questions

Question 1.
Have you ever seen pictures of mountains or volcanoes? Can you think of how the slow movement of tectonic plates helps in their formation?
Answer:
The slow movement of tectonic plates causes them to collide, separate or slide past one another. These movements lead to the formation of mountains when plates collide and volcanoes when magma rises through cracks in the Earth’s crust.

Question 2.
“The lithosphere is broken into tectonic plates that move continuously.” Explain how the asthenosphere helps in the movement of these plates and why this movement is important for shaping the Earth’s surface.
Answer:
The asthenosphere is a hot, mobile layer of partially molten rock beneath the lithosphere. It allows tectonic plates to move slowly. Their movement forms mountains, volcanoes and earthquakes, continuously reshaping the Earth’s surface over long periods.

Question 3.
Name two major tectonic plates of the world that meet along active plate boundaries and briefly explain them.
Answer:
Two major tectonic plates that meet along active plate boundaries are the Pacific Plate and the Eurasian Plate. The Pacific Plate is the largest oceanic plate, while the Eurasian Plate covers Europe and much of Asia. Their interaction along active boundaries causes earthquakes, volcanic eruptions and the formation of mountains.

Question 4.
What physical phenomenon is observed when two continental plates collide along a convergent boundary?
Answer:
When two continental plates collide at a convergent boundary, the Earth’s crust folds and rises to form fold mountains. This process creates high mountain ranges, such as the Himalayas, through continuous plate movement.

Question 5.
Observe a nearby riverbank, roadside, hill slope or open ground. Can you identify whether weathering or erosion is taking place? Give a reason for your answer.
Answer:
If I observe that soil and small stones have been washed away from a riverbank after heavy rainfall, it is an example of erosion because the weathered materials are carried from one place to another by flowing water.

Question 6.
Distinguish between physical weathering and chemical weathering.
Answer:
The differences between physical weathering and chemical weathering are

Physical Weathering	Chemical Weathering
Breaks rocks into smaller pieces without changing their chemical composition.	Changes the chemical composition of rocks by forming new substances.
Caused by temperature changes, frost or wind.	Caused by reactions with water, air or acids.

Question 7.
A farmer builds small earthen embankments around his field to prevent rainwater from washing away the fertile soil. Name this soil conservation practice and explain how it helps conserve soil.
Answer:
The soil conservation practice is called bunding. It involves constructing earthen embankments along contour lines to slow down the flow of rainwater, reduce surface run-off, and prevent soil erosion. It also helps increase water infiltration and retains soil moisture, thereby conserving fertile topsoil.

Question 8.
Relate the different stages of a river (upper and lower course) with the landforms formed in each stage.
Answer:
The different stages of a river are
• Upper course Forms V-shaped valleys, waterfalls and rapids due to steep slopes and strong erosion.
• Lower course Forms deltas, levees and alluvial fans due to heavy deposition of sediments near the river’s mouth.

Question 9.
What is a sea stack, and how is it related to a sea arch?
Answer:
A sea stack is an isolated vertical pillar of rock formed along the coast by wave erosion. It is directly related to a sea arch because when a sea arch is continuously eroded and collapses due to wave action, the remaining separated rock mass stands as a sea stack.

Question 10.
Define Karst Topography. What rock type is necessary for its formation?
Answer:
Karst topography is a landscape formed by the dissolution of soluble rocks through groundwater action. It is characterised by features such as caves and sinkholes. Limestone is the essential rock type required for its formation.

Short Answer Questions

Question 1.
Discuss how convection currents in the mantle act as the main mechanism for plate tectonic movements.
Answer:
Convection currents in the mantle are produced by heat from the Earth’s core. Hot, semi-molten material rises, while cooler material sinks back into the mantle. This continuous circular movement creates convection currents that push and pull the tectonic plates resting on the lithosphere.

As a result, the plates move slowly in different directions. Their movement leads to the formation of mountains, volcanoes, earthquakes and ocean basins, making convection currents the main driving force behind plate tectonics.

Question 2.
Explain the physical process of subduction that occurs when an oceanic plate collides with a continental plate.
Answer:
Subduction is the process in which a denser oceanic plate sinks beneath a continental plate when the two plates collide at a convergent boundary. Since the oceanic plate is heavier, it is forced downward into the mantle beneath the continental plate.

As it descends, the intense heat and pressure cause part of the plate to melt and form magma. This magma may rise to the Earth’s surface and create volcanoes.

The collision also forms deep ocean trenches and generates earthquakes. Thus, subduction is an important geological process that continuously reshapes the Earth’s surface by forming new landforms and releasing internal energy.

Question 3.
Contrast the main differences between weathering and erosion. Use a table to present your comparison.
Answer:
The main differences between weathering and erosion are as follows

Basis of Comparison	Weathering	Erosion
Meaning	The process of breaking rocks into smaller pieces.	The process of removing and transporting weathered materials.
Movement of Material	Rocks break down but remain at the same place.	Rock fragments are carried away to another place.
Agents Involved	Physical, chemical, and biological processes.	Running water, wind, glaciers, sea waves and groundwater.

Question 4.
Describe the “Zabo System” of water and soil conservation practiced in Nagaland, highlighting its relevance to modern ecological sustainability.
Answer:
The Zabo System is a traditional method of water and soil conservation practiced in Nagaland that makes efficient use of natural resources. In this system, rainwater flowing from forested hill slopes is collected and stored in ponds before being used for irrigation, livestock and household purposes. It also reduces soil erosion, improves soil fertility and helps recharge groundwater. The Zabo System promotes sustainable agriculture by conserving water and protecting the environment.

It remains highly relevant today because it supports ecological sustainability through the wise and eco-friendly management of natural resources.

Question 5.
“Landforms have played a major role in shaping the history of human civilisations.” Substantiate this statement with examples of how rivers and mountains influenced Indian history.
Answer:
Landforms have played a major role in shaping the history of human civilisations by influencing settlement, agriculture, trade and defence. Fertile plains of the Indus and Ganga rivers supported agriculture and led to the growth of early civilisations and towns. Rivers also provided water, transport, and trade routes. The Flimalayas acted as a natural barrier, protecting India from many invasions and influencing its climate. At the same time, mountain passes such as the Khyber Pass allowed trade and cultural exchanges with neighbouring regions. Thus, rivers and mountains significantly shaped India’s history, economy and culture.

Question 6.
Explain the formation of a waterfall, detailing how hard and soft rock layers facilitate its vertical drop.
Answer:
A waterfall is formed when a river flows over alternating layers of hard and soft rocks. The softer rock is eroded more quickly by the flowing water, while the harder rock resists erosion. As the softer rock is worn away, it creates a steep vertical drop, leaving the hard rock projecting over the edge. Eventually, the unsupported hard rock collapses, and the waterfall gradually retreats upstream. This continuous process of erosion and collapse shapes the waterfall and the surrounding landscape over time.

Question 7.
Choose any two agents of erosion (running water, sea waves, glaciers, wind or groundwater) and find out the following.
(i) Which landforms are created by each agent?
(ii) Are the landforms formed mainly by erosion, deposition, or both?
(iii) How are these landforms useful to people (such as for tourism, agriculture, transport or fishing)?
Answer:
Two agents of erosion: running water and sea waves

Agent of Erosion	Landforms Created	Main Process	Usefulness to People
Running water	V-shaped valleys, waterfalls, floodplains, deltas	Both erosion and deposition	Floodplains and deltas support agriculture and settlements.
Sea waves	Cliffs, sea caves, sea arches, sea stacks, wave-cut platforms	Mainly erosion	Coastal landforms attract tourists and some coasts support fishing and harbours.

Question 8.
Explain how moraines are formed. Mention any two types of moraines with their positions relative to a glacier.
Answer:
Moraines are formed when a glacier melts and deposits the rocks, soil and other debris (till) it has carried. These deposited materials accumulate to form different types of moraines.
Two types of moraines with their positions relative to a glacier are
(i) Lateral moraine Forms along the sides of a glacier.
(ii) Terminal moraine Forms at the front (snout/end) of a glacier, marking its farthest advance.

Question 9.
Explain the development and physical structure of a Yardang. How does it differ from a Dune?
Answer:
A yardang is a long, narrow ridge formed by the continuous erosion of soft rocks by strong winds in desert regions. Strong winds erode the softer rocks more rapidly than the harder rocks through abrasion and deflation, leaving behind long, streamlined ridges called yardangs.

These ridges are aligned parallel to the prevailing wind direction and have steep sides. In contrast, a dune is formed by the deposition of sand carried by the wind. Thus, a yardang is an erosional landform made of rock, whereas a dune is a depositional landform made of loose sand.

Question 10.
While exploring a limestone cave, a tourist observed pointed formations hanging from the roof and others rising from the floor. Explain how these formations are created by the action of underground water.
Answer:
The pointed formations hanging from the roof and rising from the floor of a limestone cave are formed by the depositional action of underground water. Rainwater absorbs carbon dioxide and forms a weak carbonic acid, which dissolves limestone as it passes through cracks in the rocks. When the water enters the cave and drips from the roof, it loses carbon dioxide and deposits calcium carbonate, forming stalactites. The dripping water continues to deposit calcium carbonate on the cave floor, forming stalagmites. Over time, these formations may join together to form a pillar or column.

Long Answer Questions

Question 1..
Describe the physical layered structure of the Earth’s interior. Explain the thickness, state of matter (solid/liquid), chemical composition and unique geological functions.
Answer:
The Earth’s interior is divided into four main layers: the crust, mantle, outer core and inner core, each have the following distinct characteristics and functions.

Layer	Thickness	State of Matter	Chemical Composition	Geological Function
Crust	30-40 km under continents; 5-7 km under oceans	Solid	Silicate rocks	Forms the Earths outer surface and supports continents and oceans.
Mantle	About 2,900 km	Mostly solid with semi-molten upper part	Silicate rocks rich in magnesium and iron	Convection currents in the mantle drive the movement of tectonic plates.
Outer Core	About 2,200 km	Liquid	Iron and nickel	Generates the Earths magnetic field through the movement of molten metals.
Inner Core	About 1,250 km	Solid	Iron and nickel	The hottest and densest layer that provides heat to the Earths interior and helps maintain the magnetic field.

Question 2.
Provide a detailed, comparative analysis of the three primary types of tectonic plate boundaries (Convergent, Divergent and Transform). For each boundary, explain the relative direction of plate movement, the crustal consequences (whether crust is created, destroyed or conserved), and at least one prominent geographic feature associated with it.
Answer:
The differences between three primary types of tectonic plate boundaries are convergent, divergent and transform boundaries are

Plate Boundary	Direction of Plate Movement	Crustal Consequence	Major Geographic Feature
Convergent Boundary	Two plates move towards each other.	Crust is destroyed when one plate subducts beneath another or is folded to form mountains.	Himalayas, Deep Ocean Trenches
Divergent Boundary	Two plates move away from each other.	New crust is created as magma rises and solidifies.	Mid-Atlantic Ridge
Transform Boundary	Two plates slide past each other horizontally.	Crust is neither created nor destroyed.	San Andreas Fault

Question 3.
“Traditional Indian water and soil conservation systems showcase a deep ecological understanding of the local landscape.” Elaborate on this statement by analysing the techniques used during the Sindhu-Sarasvati civilisation and the guidelines found in Kautilya’s Arthashastra.
Answer:
The techniques used during the Sindhu-Sarasvati civilisation and the guidelines found in Kautilya’s Arthashastra are

1. The Sindhu-Sarasvati Civilisation used techniques such as contouring, bunding, terracing, dams and canals to conserve water and prevent soil erosion.
2. These methods stored rainwater, improved irrigation and supported agriculture.
3. Kautilya’s Arthashastra provided guidelines for assessing land and classifying it according to its fertility and productivity.
4. It also emphasised proper land management and the efficient use of water resources.
5. These traditional practices conserved natural resources, protected the environment and promoted sustainable agriculture.

Question 4.
If you are planning a trek in a snow-covered mountain region, what precautions should you take to reduce the risk of avalanches?
Answer:
If I were planning a trek in a snow-covered mountain region, I would take the following precautions to reduce the risk of avalanches.

1. Check weather forecasts and avalanche warnings before starting the trek and avoid travelling during or after heavy snowfall.
2. Stay on marked trails and avoid walking on steep snow-covered slopes where avalanches are more likely to occur.
3. Follow the instructions of local authorities and experienced guides and never ignore warning signs.
4. Carry essential safety equipment, such as an avalanche beacon, shovel, probe, first-aid kit and communication device, for emergencies.
5. Avoid activities that may disturb unstable snow, such as trekking in restricted areas or making loud vibrations and always trek in a group so that help is available in case of an emergency.

Case-Based Questions

Question 1.
Read the case given below and answer the following questions.

The Ring of Fire and the 2001 Gujarat Earthquake
Plate tectonics plays a major role in shaping the Earth’s surface. The movement of plates leads to the formation of mountains, valleys, ocean basins, volcanoes and earthquakes. It also explains the distribution of continents and oceans across the Earth. Most earthquakes and volcanoes occur along plate boundaries, especially around the Pacific Ocean, an area known as the Ring of Fire.

The theory of plate tectonics helps us understand how the Earth’s surface is constantly changing. It explains the origin of many landforms and natural disasters. This theory is very important for identification of earthquake and volcano prone regions and managing disasters arising from them. India has experienced some major earthquakes in the past, resulting in thousands of deaths. A large earthquake in a densely populated country like India can cause severe damage to life and environment.

(i) Why is the theory of plate tectonics useful for disaster management?
Answer:
The theory of plate tectonics is useful for disaster management because it helps identify earthquake- and
volcano-prone regions, enabling better planning and preparedness.

(ii) Why are regions around the Pacific Ocean more vulnerable to earthquakes and volcanoes?
Answer:
Regions around the Pacific Ocean are more vulnerable to earthquakes and volcanoes because they are located along active plate boundaries where tectonic plates frequently interact.

(iii) Explain any two ways in which the theory of plate tectonics helps us understand the Earth’s surface,
Answer:
The theory of plate tectonics helps us understand the Earth’s surface in the following ways

• It explains the formation of major landforms such as mountains, valleys, ocean basins, and volcanoes.
• It helps identify regions that are more likely to experience earthquakes and volcanic eruptions, supporting disaster preparedness and risk reduction.

Question 2.
Read the case given below and answer the following questions.
Traditional Indian Water and Soil Conservation Systems
The Sindhu-Sarasvati civilisation employed sophisticated techniques, including contouring, bunding, terracing, dams and canals for water management, Multiple Sanskrit texts document these practices, including the Vedas, Krishi-Parasara, Kautilya’s Arthashastra and specialised treatises like Vrkshayurveda. The Arthashastra contains detailed guidelines on land assessment and categorisation based on fertility and productivity.

The Zabo system in Nagaland represents an integrated farming approach using earthen bunds on hillslopes for soil and water conservation, Check dams were constructed across small streams to reduce water velocity, prevent soil erosion and allow sediment deposition. These structures were designed to slow down water flow and enhance groundwater recharge.

(i) Why did the Sindhu-Sarasvati civilisation use techniques such as contouring, bunding and terracing?
Answer:
The Sindhu-Sarasvati civilisation used techniques such as contouring, bunding and terracing to conserve water,
reduce soil erosion, and improve agricultural productivity.

(ii) How do check dams in the Zabo system help conserve water?
Answer:
Check dams in the Zabo system help conserve water by slowing down the flow of water, reducing soil erosion and increasing groundwater recharge.

(iii) Explain any two ways in which traditional Indian water and soil conservation systems promote sustainable use of natural resources.
Answer:
Traditional Indian water and soil conservation systems promote the sustainable use of natural resources in the following ways

• They conserve water by storing rainwater and reducing surface run-off.
• They prevent soil erosion and improve soil fertility, supporting sustainable agriculture and environmental conservation.

Map-Based Questions

Question 1.
On the outline map of world, locate and label the following.

(i) Himalayas
(ii) Baratang Island (Mud Volcano)
(iii) Sundarbans Delta
(iv) Nagaland
Answer:

Question 2.
On the outline map of the world, identify and shade the following.

(i) Pacific Ring of Fire
(ii) Pacific Ocean
(iii) Mid-Atlantic Ridge
(iv) San Andreas Fault
Answer:

Think and Answer

Question 1.
Two regions receive the same amount of rainfall. One has thick vegetation, while the other is almost barren. Which region is likely to experience more soil erosion? Give two reasons for your answer.
Answer:
The almost barren region is likely to experience more soil erosion because
• There are no plant roots to hold the soil together.
• Rainwater flows rapidly over the exposed land and carries away the topsoil.

Question 2.
An agricultural land developer plans to clear all natural forest cover on a series of steep hillsides to plant commercial crops, As an environmental consultant, draft an objection report explaining the geomorphic risks of this plan, including weathering, rain run-off, mass wasting and sedimentation in local rivers.
Answer:
Objection Report
I strongly oppose the removal of natural forest cover from the steep hillsides.

Reasons

1. Without trees, the soil becomes loose and is more easily broken down by weathering.
2. Heavy rain will increase surface run-off, washing away fertile topsoil.
3. The unstable slopes will become more prone to landslides and other forms of mass wasting.
4. The eroded soil will be deposited in nearby rivers, causing sedimentation, reducing river depth and increasing the risk of floods.

Question 3.
Document a case of a glacier or glacial lake outburst flood (GLOF) that occurred in India or any other country. Highlight its causes and effects on people, settlements and the environment.
Answer:
Chamoli Glacial Lake Outburst Flood (Uttarakhand, India), 2021

1. In February 2021, a massive rock and ice avalanche in the Chamoli district of Uttarakhand triggered a sudden flood in the Rishiganga and Dhauliganga rivers. The disaster is believed to have been caused by the collapse of a large mass of rock and glacier ice, leading to a surge of water and debris downstream.

Effects on people, settlements and the environment

1. Many people lost their lives, and several others went missing.
2. Houses, roads and bridges were washed away, disrupting transport and communication.
3. Hydroelectric power projects suffered severe damage.
4. River ecosystems were disturbed due to large amounts of debris and sediment.
5. Local communities faced loss of livelihoods and displacement.

This event highlighted the importance of glacier monitoring, early warning systems and disaster preparedness in Himalayan regions.

Question 4.
Imagine you are a geologist examining a rocky coastline. You observe a series of sea caves, a fully intact sea arch, and an isolated sea stack nearby. Reconstruct the step-by-step geological timeline of this coastline, explaining how wave erosion will continue to alter these features over the next 1000 years.
Answer:
The wave erosion will continue to alter these features over the next 1000 years in the following ways

1. Waves first erode cracks in the sea cliff to form sea caves.
2. Continued erosion enlarges the caves until they meet, forming a sea arch.
3. Over time, the roof of the arch collapses due to continuous wave action, leaving behind a sea stack.
4. In the future, waves will keep eroding the sea stack until it is reduced to a stump or disappears below sea level.

Question 5.
Form groups of 4-6 students. Identify and compare any two natural hazards (such as dust storms, avalanches, landslides, earthquakes or floods) using credible sources such as government websites, newspapers or disaster management reports. Present your findings in a chart or poster using bullet points, symbols, diagrams or colour coding.

Parameter	Natural Hazard 1	Natural Hazard 2	Source
Causes
Regions where it commonly occurs
Effects on people and the environment
Precautionary measures
Government/community response

Answer:

Parameter	Dust Storm	Avalanche	Source
Causes	Strong winds lift loose, dry soil and sand into the air due to drought, low rainfall and sparse vegetation.	Heavy snowfall, unstable snow layers, rising temperatures, earthquakes or human activities trigger the sudden movement of snow.	NCERT; India Meteorological Department (IMD); National Disaster Management Authority (NDMA)
Regions where it commonly occurs	Desert and semi-arid regions such as the Thar Desert in Rajasthan, Gujarat and parts of Haryana.	Himalayan regions such as Jammu & Kashmir, Himachal Pradesh, Uttarakhand and Sikkim.	NCERT; IMD; NDMA
Effects on people and the environment	Reduces visibility, damages crops, affects transport and causes breathing problems.	Causes loss of life, damages roads, buildings and forests, and blocks transport routes.	NCERT; NDMA
Precautionary measures	Stay indoors, wear masks and protective eyewear, and avoid travelling during severe dust storms.	Follow avalanche warnings, avoid steep snow-covered slopes, carry safety equipment and follow trained guides.	NDMA; IMD
Government/community response	Early weather warnings, afforestation, soil conservation and public awareness programmes.	Avalanche forecasting, rescue teams, early warning systems and disaster preparedness programmes.	NDMA; IMD

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