2: Shaping of the Earth's Surface
Section A: Multiple Choice
Questions (70)
1. Who proposed the theory
of plate tectonics?
(a) Alfred Wegener (b) W.J. Morgan (c) Charles Darwin (d) James Hutton
Answer: (b)
W.J. Morgan
2. The outermost layer of
the Earth on which we live is called the:
(a) Mantle (b) Core
(c) Crust (d) Asthenosphere
Answer: (c)
Crust
3. Which layer of the
Earth is extremely hot, heavy and forms the innermost part?
(a) Crust (b) Mantle (c) Core
(d) Lithosphere
Answer: (c)
Core
4. The lithosphere is
composed of:
(a) Only the crust (b) Crust and upper mantle (c) Only the mantle (d) Core and mantle
Answer: (b)
Crust and upper mantle
5. Which layer lies
beneath the lithosphere and allows plates to move?
(a) Asthenosphere (b) Outer core (c) Inner core (d) Crust
Answer: (a)
Asthenosphere
6. Oceanic crust is
approximately how thick?
(a) 30–40 km (b) 5–7 km (c) 100 km (d) 200 km
Answer: (b)
5–7 km
7. Continental crust
thickness varies from:
(a) 5–7 km (b) 100–150 km (c) 30–40 km (d) 200–250 km
Answer: (c)
30–40 km
8. Tectonic plates that
carry only ocean floors are called:
(a) Continental
plates (b) Oceanic plates (c) Mixed plates (d) Transform plates
Answer: (b)
Oceanic plates
9. Which of the following
is NOT a major tectonic plate?
(a) Pacific Plate (b) Eurasian Plate (c) Indo-Australian Plate (d) Himalayan Plate
Answer: (d)
Himalayan Plate
10. The movement of
tectonic plates is mainly caused by:
(a) Gravity (b) Convection currents in the mantle (c) Wind pressure (d) Ocean currents
Answer: (b)
Convection currents in the mantle
11. The edges where
tectonic plates meet are called:
(a) Plate margins (b) Plate boundaries (c) Fault lines (d) Fold zones
Answer: (b)
Plate boundaries
12. At a convergent
boundary, plates:
(a) Move away from each
other (b) Move towards each other (c) Slide past each other (d) Remain stationary
Answer: (b)
Move towards each other
13. Fold mountains like
the Himalaya are formed when:
(a) Oceanic plates
diverge (b) Two continental plates
collide (c) Plates slide past each
other (d) Oceanic plates diverge from
continental plates
Answer: (b)
Two continental plates collide
14. When an oceanic plate
collides with a continental plate, the oceanic plate:
(a) Rises above the
continental plate (b) Sinks beneath
the continental plate (c) Remains
unchanged (d) Splits into two
Answer: (b)
Sinks beneath the continental plate
15. At a divergent
boundary, magma rises to form:
(a) Fold mountains (b) New crust / mid-ocean ridges (c) Deep trenches (d) Fault lines only
Answer: (b)
New crust / mid-ocean ridges
16. Which of the following
is an example of a divergent boundary?
(a) San Andreas Fault (b) Himalaya (c) Mid-Atlantic Ridge (d) Andes
Answer: (c)
Mid-Atlantic Ridge
17. At a transform
boundary, plates:
(a) Collide head-on (b) Move apart (c) Slide past each other (d) Sink into the mantle
Answer: (c)
Slide past each other
18. The San Andreas Fault
in the USA is an example of a:
(a) Convergent
boundary (b) Divergent boundary (c) Transform boundary (d) Subduction zone
Answer: (c)
Transform boundary
19. The zone around the
Pacific Ocean known for frequent earthquakes and volcanoes is called:
(a) Ring of Ice (b) Ring of Fire (c) Pacific Belt (d) Volcanic Arc
Answer: (b)
Ring of Fire
20. Which ancient Indian
text contains a section dedicated to earthquakes?
(a) Arthashastra (b) Brihatsamhita (c) Vrikshayurveda (d) Rigveda
Answer: (b)
Brihatsamhita
21. Earthquakes were
traditionally known in India as:
(a) Prithvi kampa (b) Bhukampa (c) Vayu kampa (d) Agni kampa
Answer: (b)
Bhukampa
22. Varahamihira
attributed earthquakes to how many elemental forces?
(a) Two (b) Three
(c) Four (d) Five
Answer: (c)
Four
23. India's only mud
volcano is located at:
(a) Andaman and Nicobar
Islands (b) Lakshadweep (c) Gujarat (d) Sikkim
Answer: (a)
Andaman and Nicobar Islands
24. The process by which
rocks break down without movement of material is called:
(a) Erosion (b) Weathering (c) Deposition (d) Transportation
Answer: (b)
Weathering
25. Rocks breaking due to
temperature changes, frost, or wind is an example of:
(a) Chemical
weathering (b) Physical
weathering (c) Biological
weathering (d) Coastal erosion
Answer: (b)
Physical weathering
26. Weathering caused by
plant roots growing into cracks of rocks is:
(a) Physical
weathering (b) Chemical
weathering (c) Biological
weathering (d) Glacial weathering
Answer: (c)
Biological weathering
27. Which type of
weathering involves reactions of minerals with water, air, or acids?
(a) Physical
weathering (b) Chemical
weathering (c) Biological
weathering (d) Wind weathering
Answer: (b)
Chemical weathering
28. Erosion differs from
weathering because erosion involves:
(a) Breaking of rocks
only (b) Movement of broken material (c) Formation of new minerals (d) No change in landscape
Answer: (b)
Movement of broken material
29. Erosion caused by
moving ice is called:
(a) Water erosion (b) Wind erosion (c) Glacial erosion (d) Coastal erosion
Answer: (c)
Glacial erosion
30. Which type of erosion
is common in dry and sandy areas?
(a) Water erosion (b) Wind erosion (c) Glacial erosion (d) Coastal erosion
Answer: (b)
Wind erosion
31. A continuous contour
trench (CCT) is primarily used for:
(a) Deforestation (b)
Water conservation (c) Mining (d) Sand mining
Answer: (b)
Water conservation
32. Earthen embankments
built along contour lines to reduce soil erosion are called:
(a) Terracing (b) Bunding (c) Contouring (d) Moraines
Answer: (b)
Bunding
33. The Zabo system of
integrated farming for soil and water conservation is practised in:
(a) Rajasthan (b) Nagaland (c) Kerala (d) Punjab
Answer: (b)
Nagaland
34. Which of the following
is NOT an agent of gradation?
(a) Running water (b) Glaciers (c) Wind
(d) Gravity alone
Answer: (d)
Gravity alone
35. Groundwater dissolving
limestone creates:
(a) Sand dunes (b) Caves and sinkholes (c) Deltas (d) Moraines
Answer: (b)
Caves and sinkholes
36. In the upper course of
a river, common landforms include:
(a) Deltas and levees (b) V-shaped valleys and waterfalls (c) Oxbow lakes (d) Floodplains
Answer: (b)
V-shaped valleys and waterfalls
37. Oxbow lakes and
floodplains are typically formed in the:
(a) Upper course of a
river (b) Middle course of a
river (c) Lower course of a river (d) Mouth of a river
Answer: (b)
Middle course of a river
38. Deltas, levees, and
alluvial fans are formed in the:
(a) Upper course (b) Middle course (c) Lower course (d) Source of a river
Answer: (c)
Lower course
39. A waterfall forms
when:
(a) Soft rocks resist
erosion better than hard rocks (b)
Hard rocks resist erosion while softer rocks below wear away (c) A river meanders repeatedly (d) Sediments accumulate at the river mouth
Answer: (b)
Hard rocks resist erosion while softer rocks below wear away
40. A winding curve or
bend in a river's course, formed by lateral erosion and deposition, is called
a:
(a) Delta (b) Meander (c) Moraine (d) Fjord
Answer: (b)
Meander
41. The Grand Anicut
(Kallanai) in Tamil Nadu is an example of use of rivers for:
(a) Flood control
only (b) Irrigation (c) Fishing only (d) Hydroelectricity
Answer: (b)
Irrigation
42. A delta is formed at:
(a) The source of a
river (b) The upper course of a
river (c) The mouth of a river (d) A glacial valley
Answer: (c)
The mouth of a river
43. Deltas are highly
fertile because of:
(a) Sandy soil (b) Rich alluvial soil (c) Rocky terrain (d) Saline soil
Answer: (b)
Rich alluvial soil
44. The Sundarbans is a
famous example of a:
(a) Glacier (b) Delta
(c) Fjord (d) Desert
Answer: (b)
Delta
45. A landform made up of
sand, pebbles, or rocks along a shoreline is called a:
(a) Beach (b) Delta
(c) Moraine (d) Dune
Answer: (a)
Beach
46. Steep rock faces
formed as waves undercut the base of the coast are called:
(a) Sea stacks (b) Cliffs (c) Sea arches (d) Wave-cut platforms
Answer: (b)
Cliffs
47. Isolated pillars of
rock left standing after arches collapse are known as:
(a) Sea stacks (b) Sea caves (c) Headlands (d) Sand bars
Answer: (a)
Sea stacks
48. Flat areas left behind
as cliffs retreat are called:
(a) Sea caves (b) Wave-cut platforms (c) Arches (d) Stacks
Answer: (b)
Wave-cut platforms
49. U-shaped valleys are
formed by the erosional action of:
(a) Rivers (b) Wind
(c) Glaciers (d) Waves
Answer: (c)
Glaciers
50. Bowl-shaped depressions
at the head of a glacier are called:
(a) Aretes (b) Cirques (c) Fjords (d) Moraines
Answer: (b)
Cirques
51. Deep, narrow inlets
created when the sea floods glacial valleys are called:
(a) Fjords (b) Cirques (c) Aretes (d) Hanging valleys
Answer: (a)
Fjords
52. Sharp ridges between
two glacial valleys are called:
(a) Cirques (b) Aretes (c) Fjords (d) Moraines
Answer: (b)
Aretes
53. Moraines are formed by
the deposition of material called:
(a) Loess (b) Till
(c) Alluvium (d) Silt
Answer: (b)
Till
54. Moraines found at the
end of glaciers, marking their furthest advance, are called:
(a) Lateral moraines (b) Terminal moraines (c) Medial moraines (d) Ground moraines
Answer: (b)
Terminal moraines
55. Medial moraines are
formed when:
(a) A single glacier
melts (b) Two glaciers meet and their
lateral moraines join (c) A glacier
reaches the sea (d) Wind deposits sand
Answer: (b)
Two glaciers meet and their lateral moraines join
56. Streamlined rock
ridges carved by wind are called:
(a) Yardangs (b) Ventifacts (c) Dunes
(d) Deflation hollows
Answer: (a)
Yardangs
57. Rocks polished and
shaped by sandblasting due to wind are called:
(a) Yardangs (b) Ventifacts (c) Barchans (d) Sinkholes
Answer: (b)
Ventifacts
58. Shallow depressions
formed where loose material is removed by wind are called:
(a) Desert pavements (b) Deflation hollows / blowouts (c) Yardangs (d) Dunes
Answer: (b)
Deflation hollows / blowouts
59. Crescent-shaped sand
dunes formed with limited sand and a single wind direction are called:
(a) Longitudinal
dunes (b) Barchan dunes (c) Star dunes (d) Parabolic dunes
Answer: (b)
Barchan dunes
60. Dunes with multiple
arms formed where winds come from different directions are called:
(a) Barchan dunes (b) Star dunes (c) Longitudinal dunes (d) Parabolic dunes
Answer: (b)
Star dunes
61. Landforms created by
underground water dissolving limestone are collectively known as:
(a) Glacial
topography (b) Karst topography (c) Desert topography (d) Coastal topography
Answer: (b)
Karst topography
62. Icicle-shaped
formations hanging from the ceiling of caves are called:
(a) Stalagmites (b) Stalactites (c) Sinkholes (d) Dolines
Answer: (b)
Stalactites
63. Formations rising from
the floor of caves are called:
(a) Stalactites (b) Stalagmites (c) Ventifacts (d) Yardangs
Answer: (b)
Stalagmites
64. Depressions formed
when the ground collapses into an underground cavity are called:
(a) Cirques (b) Sinkholes / dolines (c) Moraines (d) Deltas
Answer: (b)
Sinkholes / dolines
65. Landslides are most
commonly triggered by:
(a) Clear sky and dry
weather (b) Heavy and continuous
rainfall (c) Low tide (d) Calm winds
Answer: (b)
Heavy and continuous rainfall
66. Which human activity
increases the risk of landslides?
(a) Afforestation (b) Deforestation and unplanned
construction (c) Terracing (d) Contour bunding
Answer: (b)
Deforestation and unplanned construction
67. Avalanches occur
mainly on:
(a) Flat plains (b) Steep mountain slopes covered with
snow (c) River deltas (d) Sandy deserts
Answer: (b)
Steep mountain slopes covered with snow
68. GLOF stands for:
(a) Glacial Lake Outburst
Flood (b) Global Lake Overflow
Force (c) Glacial Land Ocean Flow (d) Great Lake Outburst Flood
Answer: (a)
Glacial Lake Outburst Flood
69. GLOFs occur mainly due
to:
(a) Excess rainfall in
deserts (b) Sudden collapse of natural
dams holding glacial lake water (c)
Ocean tides (d) Wind erosion
Answer: (b)
Sudden collapse of natural dams holding glacial lake water
70. Dust storms are most
common in:
(a) Coastal and humid
regions (b) Desert and semi-arid
regions (c) Glacial regions (d) Deltaic regions
Answer: (b)
Desert and semi-arid regions
Section B:
Short Answer Questions (30)
That's a very large set (30 short
answers + 30 long answers), which is far too much to fit in a single response.
I can definitely provide all the answers, but I'll need to split them into
parts.
Part
1: Section B (Short Answer Questions 1–30)
1. Define plate tectonics.
Plate tectonics is the theory that the Earth's lithosphere is divided into
large and small plates that move slowly over the semi-molten asthenosphere.
Their movement causes earthquakes, volcanoes, and mountain formation.
2. Name the three main layers of the
Earth.
The three main layers of the Earth are:
·
Crust
·
Mantle
·
Core
3. What is the lithosphere?
The lithosphere is the Earth's rigid outer layer made up of the crust and the
uppermost mantle. It is broken into tectonic plates that move over the
asthenosphere.
4. What is the asthenosphere and why
is it significant?
The asthenosphere is a soft, semi-molten layer beneath the lithosphere. It
allows tectonic plates to move, making it important for earthquakes, volcanic
activity, and continental drift.
5. Name the three main types of
tectonic plates.
The three main types are:
·
Continental
plates
·
Oceanic
plates
·
Mixed
(continental-oceanic) plates
6. What causes the movement of
tectonic plates?
Plate movement is caused mainly by convection currents in the mantle, along
with ridge push and slab pull forces.
7. Define plate boundary and name
its three types.
A plate boundary is the region where two tectonic plates meet. The three types
are:
·
Divergent
boundary
·
Convergent
boundary
·
Transform
boundary
8. How are fold mountains like the
Himalaya formed?
Fold mountains form when two continental plates collide. The rocks are
compressed, folded, and uplifted. The Himalaya formed due to the collision of
the Indian Plate and the Eurasian Plate.
9. What happens when an oceanic
plate meets a continental plate?
The denser oceanic plate sinks beneath the continental plate in a process
called subduction. This creates deep ocean trenches, volcanoes, and
earthquakes.
10. What is the Ring of Fire?
The Ring of Fire is a belt around the Pacific Ocean where many earthquakes and
volcanoes occur because of active tectonic plate boundaries.
11. What is a landform? Give two
examples.
A landform is a natural feature of the Earth's surface. Examples include
mountains and plains.
12. Differentiate between weathering
and erosion.
|
Weathering |
Erosion |
|
Breakdown of rocks at
the same place. |
Removal and transport of
weathered material. |
|
No movement involved. |
Involves movement by
water, wind, ice, etc. |
13. Name the three types of
weathering with one example each.
·
Physical
weathering – Frost action.
·
Chemical
weathering – Rusting (oxidation).
·
Biological
weathering – Tree roots breaking rocks.
14. What are agents of gradation?
Name any three.
Agents of gradation are natural forces that wear away and deposit materials on
the Earth's surface. Examples include rivers, glaciers, and wind.
15. Define a waterfall and explain
how it forms.
A waterfall is a vertical drop in a river's course. It forms when soft rocks
erode faster than hard rocks, creating a steep edge over which water falls.
16. What is a meander? Why is it
important for humans?
A meander is a winding bend in a river. It creates fertile floodplains useful
for agriculture and supports human settlements.
17. Define a delta and mention two
of its uses.
A delta is a triangular landform formed by the deposition of sediments at a
river's mouth. It provides fertile land for farming and supports fishing.
18. What is a beach? How is it
formed?
A beach is a sandy or pebbly shore along a sea or lake. It forms due to the
deposition of sediments by waves and currents.
19. Explain the formation of a sea
arch.
Sea waves first form caves by eroding weak rock. Continued erosion enlarges the
caves until they meet, forming a sea arch.
20. What are moraines? Name any two
types.
Moraines are deposits of rocks and soil left behind by glaciers. Types include:
·
Lateral
moraine
·
Terminal
moraine
21. What is a cirque? Where is it
formed?
A cirque is a bowl-shaped hollow formed by glacial erosion at the head of a
mountain valley.
22. What is a fjord?
A fjord is a deep, narrow sea inlet formed when seawater fills a glacial valley
after the glacier melts.
23. Define yardangs and ventifacts.
·
Yardangs: Long ridges carved by wind erosion
in deserts.
·
Ventifacts: Rocks polished and shaped by
wind-blown sand.
24. What are sand dunes? Name two
types.
Sand dunes are hills of sand formed by wind deposition. Two types are:
·
Barchan
dunes
·
Longitudinal
dunes
25. What is karst topography?
Karst topography is a landscape formed by the dissolution of limestone,
featuring caves, sinkholes, stalactites, and stalagmites.
26. Differentiate between
stalactites and stalagmites.
|
Stalactites |
Stalagmites |
|
Hang from cave roofs. |
Rise from cave floors. |
|
Form from dripping
mineral-rich water. |
Form from mineral
deposits on the ground. |
27. What causes landslides? (State
any three factors.)
·
Heavy
rainfall
·
Earthquakes
·
Deforestation
28. What is an avalanche?
An avalanche is the sudden downward movement of a large mass of snow, ice, and
rocks down a mountain slope.
29. Explain the term GLOF.
A Glacial Lake Outburst Flood (GLOF) is a sudden flood caused when a glacial
lake bursts due to failure of its natural dam.
30. What causes dust storms?
Dust storms occur due to strong winds lifting loose, dry soil in arid and
semi-arid regions. Drought, lack of vegetation, and dry weather increase their
occurrence.
Section C:
Long Answer Questions (30)
1. Explain the
theory of plate tectonics and its significance in understanding the Earth's
surface.
The theory of plate tectonics states
that the Earth's lithosphere is divided into several large and small tectonic
plates. These plates float on the semi-molten asthenosphere and move slowly due
to convection currents in the mantle. Plate movements may be convergent (moving
together), divergent (moving apart), or transform (sliding past each other).
These movements create mountains, earthquakes, volcanoes, and ocean basins. For
example, the collision of the Indian Plate with the Eurasian Plate formed the
Himalayas. Plate tectonics also explains continental drift, the distribution of
earthquakes and volcanoes, and the formation of new ocean floors. It is one of
the most important theories in geology because it helps scientists understand
how the Earth's surface changes over time.
2. Describe the internal
structure of the Earth with the help of a labelled diagram.
The Earth has three main layers: the
crust, mantle, and core. The crust
is the thin outermost layer where humans live. It is divided into continental
and oceanic crust. Beneath it lies the mantle,
which extends about 2,900 km deep. The upper mantle contains the asthenosphere,
where convection currents occur and move tectonic plates. The core is divided into
the outer core and inner core. The outer core is liquid and made mainly of iron
and nickel, while the inner core is solid due to immense pressure. The core is
the hottest part of the Earth.
Diagram:
Earth ___________ / \ | Crust | |------------| | Mantle | |------------| | Outer Core | |------------| | Inner Core | \___________/3. Explain the
three types of plate boundaries with examples of landforms formed at each.
Plate boundaries are places where
tectonic plates meet.
Convergent boundaries occur when two plates move towards
each other. They form fold mountains, trenches, and volcanoes. Example:
Himalayas.
Divergent boundaries occur when plates move apart. Magma
rises to fill the gap, forming mid-ocean ridges and rift valleys. Example:
Mid-Atlantic Ridge.
Transform boundaries occur when two plates slide past
each other. They do not create or destroy crust but often cause earthquakes.
Example: San Andreas Fault.
Each type of plate boundary plays an
important role in shaping the Earth's surface and is responsible for many
geological events.
4. “Plate movements
are responsible for the distribution of earthquakes and volcanoes.” Explain
this statement.
Earthquakes and volcanoes occur
mainly along tectonic plate boundaries because these are zones of intense
geological activity. At convergent boundaries, one plate may sink beneath
another, producing earthquakes and volcanic eruptions. At divergent boundaries,
magma rises through cracks to create volcanoes and new crust. At transform
boundaries, plates slide past each other, causing earthquakes due to friction.
Most earthquakes and volcanoes occur around the Pacific Ring of Fire because
several active plates meet there. The movement of tectonic plates releases enormous
amounts of energy, making plate tectonics the main reason for the uneven
distribution of earthquakes and volcanoes across the world.
5. Explain the
causes and effects of earthquakes, referring to India's vulnerability.
Earthquakes are caused by sudden
movements of tectonic plates, volcanic activity, and faulting. They release
energy in the form of seismic waves. Their effects include loss of life,
destruction of buildings, landslides, tsunamis, and damage to roads and bridges.
India is highly vulnerable because it lies near the active boundary between the
Indian Plate and the Eurasian Plate. The Himalayan region, northeastern states,
Gujarat, and the Andaman and Nicobar Islands fall under high-risk seismic
zones. Major earthquakes like the 2001 Gujarat earthquake have caused heavy
destruction. Earthquake-resistant buildings, early warning systems, and public
awareness can reduce the impact.
6. Describe the
three types of weathering with suitable examples.
Weathering is the breakdown of rocks
at or near the Earth's surface.
Physical weathering breaks rocks into smaller pieces
without changing their chemical composition. Example: Frost action in
mountains.
Chemical weathering changes the mineral composition of
rocks through chemical reactions such as oxidation, hydration, and carbonation.
Example: Limestone dissolving in rainwater.
Biological weathering is caused by living organisms. Tree
roots grow into rock cracks and widen them, while animals and microorganisms
also contribute to rock breakdown.
Together, these processes help form
soil and prepare rock material for erosion by rivers, glaciers, and wind.
7. Explain the
difference between weathering and erosion with examples.
Weathering is the process of
breaking rocks into smaller pieces at the place where they are found. It does
not involve movement. For example, rocks crack due to repeated freezing and
thawing.
Erosion is the removal and
transportation of weathered materials by agents such as rivers, glaciers, wind,
and sea waves. For example, a river carries sand and gravel downstream.
Weathering prepares rocks for erosion,
while erosion transports the broken material and deposits it elsewhere. Both
processes work together to shape landforms such as valleys, plains, and
beaches.
8. Discuss the
various agents of gradation and how each shapes the Earth's surface.
Gradation is the process of wearing
down high areas and filling low areas through erosion and deposition. The main
agents are rivers, glaciers, wind, sea waves, and underground water.
Rivers form valleys, waterfalls,
floodplains, and deltas.
Glaciers create U-shaped valleys, cirques,
moraines, and fjords.
Wind shapes deserts by forming sand
dunes, yardangs, and ventifacts.
Sea waves produce cliffs, beaches, caves,
arches, and stacks.
Underground water dissolves limestone to create
caves, sinkholes, stalactites, and stalagmites.
These agents continuously modify the
Earth's surface over millions of years.
9. Explain how
erosion affects human occupations such as farming, fishing, and construction.
Erosion has both positive and
negative effects on human occupations. River erosion and deposition create
fertile floodplains, which support agriculture. However, excessive erosion
removes fertile topsoil and reduces crop production. Coastal erosion damages
fishing villages, harbours, and beaches, affecting fishing activities and
tourism. In construction, erosion weakens the foundations of buildings, roads,
and bridges, increasing maintenance costs and the risk of collapse. Soil
conservation methods such as afforestation, terracing, contour farming, and
proper drainage help reduce erosion and protect livelihoods.
10. Describe the
traditional Indian water conservation techniques of contouring, bunding, and
terracing.
Traditional Indian farming uses
several methods to conserve soil and water.
Contouring involves ploughing and planting
along contour lines of hills. This slows the flow of rainwater and reduces soil
erosion.
Bunding involves building small earthen
embankments across fields to hold rainwater and prevent soil from being washed
away.
Terracing converts steep slopes into flat
steps. It reduces runoff, conserves water, and allows farming on hillsides.
These methods improve groundwater
recharge, increase agricultural productivity, prevent erosion, and promote
sustainable farming, especially in hilly and semi-arid regions.
11. Explain the
process of river erosion and describe the landforms formed in the upper,
middle, and lower courses.
River erosion is the wearing away of
rocks and soil by the flowing water of a river. The river erodes, transports,
and deposits sediments as it flows from its source to its mouth. In the upper course, the
river flows rapidly and forms V-shaped valleys, gorges, rapids, and waterfalls.
In the middle course,
the river flows more slowly and forms meanders, floodplains, and oxbow lakes.
In the lower course,
the river has a gentle slope and deposits sediments, forming wide floodplains,
natural levees, and deltas. These landforms support agriculture,
transportation, fishing, and human settlements.
12. Describe the
formation and importance of waterfalls with a labelled diagram.
A waterfall is a steep vertical drop
in the course of a river. It usually forms where a layer of hard rock lies
above a softer rock. The softer rock is eroded more quickly than the hard rock,
creating a sudden drop. As erosion continues, the waterfall retreats upstream,
leaving behind a gorge. Waterfalls are important because they generate
hydroelectric power, attract tourists, provide scenic beauty, and support
biodiversity. Famous examples include the Jog Falls in India and Niagara Falls
in North America.
Labelled Diagram:
River Flow----------------------------> Hard Rock Layer____________________________ | | Waterfall↓
Soft Rock~~~~~~~~~~~~~~~~~~~~~~~~ Plunge Pool13. Explain how
meanders form and their significance for human settlements and agriculture.
A meander is a winding bend in a
river. It forms mainly in the middle and lower courses where the river flows
more slowly. The river erodes the outer bank due to faster flow and deposits
sediments on the inner bank where the flow is slower. This continuous erosion
and deposition create large bends called meanders. Meanders are important
because they form fertile floodplains that are ideal for agriculture. They also
provide water for irrigation, support fishing, and encourage the development of
towns and villages along riverbanks. Their scenic beauty also promotes tourism.
14. Describe the
formation of deltas and explain their economic importance.
A delta is formed when a river
enters a sea or lake and slows down, causing it to deposit sediments carried
from upstream. Over time, these sediments accumulate and form a triangular or
fan-shaped landform called a delta. The river often divides into several
smaller channels called distributaries. Deltas are economically important
because they have fertile soil suitable for farming crops like rice. They
support fishing, provide freshwater, encourage trade through waterways, and
contain rich biodiversity. The Sundarbans Delta, formed by the Ganga,
Brahmaputra, and Meghna rivers, is the world's largest delta.
15. Explain the
various landforms created by wave and current action along coastlines.
Sea waves and ocean currents
continuously erode, transport, and deposit materials along coastlines. Erosional landforms
include sea cliffs, wave-cut platforms, sea caves, sea arches, and sea stacks. Depositional landforms
include beaches, spits, bars, lagoons, and sandbars. Waves erode rocky coasts
by hydraulic action and abrasion, while currents transport sand and pebbles
before depositing them in calmer areas. These coastal landforms protect the
shoreline, support tourism, provide habitats for marine life, and create
suitable locations for ports and fishing activities.
16. Describe the
process of coastal erosion and the landforms it creates (cliffs, caves, arches,
stacks).
Coastal erosion is caused by
powerful sea waves striking rocky shores. Hydraulic action, abrasion, and
solution gradually wear away the rocks. Initially, cracks in cliffs enlarge
into sea caves. Continuous erosion deepens the caves, and when caves on
opposite sides meet, they form a sea arch. As erosion weakens the roof of the
arch, it collapses, leaving behind an isolated pillar called a sea stack. The
steep rocky edge is called a sea cliff. These landforms demonstrate the
continuous action of waves and are popular tourist attractions.
17. Explain the
landforms created by glacial erosion, with examples.
Glaciers are large masses of moving
ice that erode rocks through plucking and abrasion. They create several
distinctive landforms. A cirque
is a bowl-shaped hollow formed at the head of a glacier. U-shaped valleys
develop as glaciers widen and deepen river valleys. Hanging valleys are
smaller valleys left above the main valley after glaciers melt. Arêtes are sharp
ridges formed between cirques. Fjords
are deep, narrow sea inlets formed when seawater floods glacial valleys. These
landforms are common in Norway, Switzerland, Canada, and the Himalayas.
18. Describe
moraines, their types, and their importance to human life.
Moraines are heaps of rocks, soil,
and other debris deposited by glaciers. They are formed when glaciers melt and
leave behind the materials they carried. The main types are lateral moraines
(along glacier sides), medial
moraines (middle of joined glaciers), terminal moraines (at
the glacier's end), and ground
moraines (beneath glaciers). Moraines enrich soil with
minerals, store groundwater, create natural lakes, and provide valuable
information about past glacial movements. They also influence agriculture and
tourism in mountainous regions.
19. Explain the
landforms created by wind erosion and deposition in desert regions.
Wind is an important agent of
erosion and deposition in deserts. Through erosion, wind forms yardangs, which are
long ridges carved from soft rocks, and ventifacts,
which are smooth, polished rocks shaped by sand-blasting. Deflation creates
shallow depressions called deflation hollows. During deposition, wind forms sand dunes, loess deposits, and
sand sheets. These landforms shape desert landscapes, influence settlement
patterns, and affect transportation. Some dunes also help protect desert
ecosystems and act as natural barriers against strong winds.
20. Describe the
different types of sand dunes and their formation.
Sand dunes are hills or ridges of
sand formed by wind deposition in deserts and coastal areas. Barchan dunes are
crescent-shaped and form where wind blows mainly from one direction and sand
supply is limited. Longitudinal
dunes are long, parallel ridges formed by winds blowing in two
directions. Transverse
dunes form at right angles to the prevailing wind where sand is
abundant. Parabolic
dunes are U-shaped and commonly found in coastal regions with
vegetation anchoring their ends. Sand dunes help reduce wind erosion, protect
coastal areas, and provide habitats for desert plants and animals.
21. Explain karst
topography and describe the landforms associated with underground water.
Karst topography is a landscape
formed by the chemical weathering of soluble rocks such as limestone, dolomite,
and gypsum by slightly acidic rainwater. As water dissolves these rocks, it
creates both surface and underground landforms. Surface features include sinkholes (dolines)
and disappearing streams. Underground features include caves, caverns, stalactites (hanging
from cave roofs), stalagmites
(rising from cave floors), and pillars
formed when stalactites and stalagmites join together. Karst regions are
important sources of groundwater and attract many tourists because of their
unique caves and rock formations.
22. Discuss the
causes of landslides and suggest mitigation measures.
Landslides are the sudden downward
movement of rocks, soil, and debris on a slope under the force of gravity.
Causes:
·
Heavy
rainfall
·
Earthquakes
·
Deforestation
·
Mining
and quarrying
·
Road
construction on steep slopes
Mitigation Measures:
·
Afforestation
to strengthen soil with tree roots.
·
Construct
retaining walls and proper drainage systems.
·
Avoid
construction on unstable slopes.
·
Monitor
landslide-prone areas using warning systems.
·
Spread
awareness and prepare evacuation plans.
These measures help reduce the
damage caused by landslides and protect lives and property.
23. Explain the
causes of avalanches and precautions to reduce their impact.
An avalanche is the rapid movement
of snow, ice, and rocks down a mountain slope.
Causes:
·
Heavy
snowfall
·
Sudden
rise in temperature
·
Earthquakes
·
Strong
winds
·
Human
activities such as skiing or blasting
Precautions:
·
Monitor
weather forecasts and avalanche warnings.
·
Avoid
travelling on steep snowy slopes during risky conditions.
·
Plant
vegetation where possible to stabilize slopes.
·
Construct
avalanche barriers and snow fences.
·
Train
rescue teams and educate local communities.
These precautions reduce the loss of
life and property in mountainous regions.
24. Describe
Glacial Lake Outburst Floods (GLOFs)—causes, effects, and mitigation.
A Glacial Lake Outburst Flood (GLOF)
occurs when a glacial lake suddenly bursts due to the failure of its natural
dam made of ice or moraines.
Causes:
·
Rapid
melting of glaciers due to climate change.
·
Heavy
rainfall.
·
Earthquakes.
·
Collapse
of moraine dams.
Effects:
·
Severe
flooding downstream.
·
Destruction
of villages, roads, and bridges.
·
Loss
of life and livestock.
·
Damage
to agriculture and hydropower projects.
Mitigation:
·
Regular
monitoring of glacial lakes.
·
Installation
of early warning systems.
·
Controlled
drainage of dangerous lakes.
·
Better
land-use planning and disaster preparedness.
25. Explain the
causes and impacts of dust storms, along with mitigation strategies.
Dust storms occur when strong winds
lift loose, dry soil and sand into the air.
Causes:
·
Drought
·
Strong
winds
·
Sparse
vegetation
·
Overgrazing
·
Deforestation
Impacts:
·
Reduced
visibility causing accidents.
·
Respiratory
diseases.
·
Damage
to crops.
·
Soil
erosion.
·
Disruption
of transport.
Mitigation:
·
Plant
shelterbelts and trees.
·
Prevent
overgrazing.
·
Use
soil conservation methods.
·
Promote
sustainable farming.
·
Issue
weather warnings before storms.
26. “Landforms have
played a major role in shaping the history of human civilisations.” Discuss
with examples.
Landforms have greatly influenced
where people live, farm, trade, and build cities. River valleys such as the Indus, Nile, and Tigris-Euphrates
supported early civilizations because they provided fertile soil and water.
Mountains offered natural protection from invasions and influenced climate.
Coastal plains encouraged fishing and trade through ports. Plateaus are rich in
minerals and support mining. Plains are suitable for agriculture and urban
development. Thus, landforms have shaped human settlement, economic activities,
transportation, culture, and the growth of civilizations throughout history.
27. Explain how
deforestation and erosion are related to each other.
Deforestation is the removal of
forests, while erosion is the wearing away of soil by natural agents. Trees
hold the soil together with their roots and reduce the force of rainfall. When
forests are cut down, the soil becomes loose and is easily washed away by rain
or blown away by wind. This increases soil erosion, landslides, floods, and
loss of fertile land. Erosion also reduces agricultural productivity and
damages ecosystems. Afforestation, controlled logging, and sustainable land
management are essential to reduce erosion and protect the environment.
28. Discuss the
internal and external forces responsible for shaping the Earth's surface.
The Earth's surface is shaped by internal (endogenic)
and external
(exogenic) forces.
Internal forces originate inside the Earth and
include plate tectonics, volcanic eruptions, earthquakes, folding, and
faulting. They build major landforms such as mountains and plateaus.
External forces act on the Earth's surface and
include weathering, erosion, transportation, and deposition by rivers,
glaciers, wind, sea waves, and underground water. They wear down highlands and
fill lowlands, creating valleys, plains, deltas, beaches, and sand dunes.
Together, these forces continuously
change and reshape the Earth's surface over millions of years.
29. Draw and
explain a labelled diagram of a meander and a delta.
Meander
River Flow→
Outer Bank (Erosion) ) )~~~~~~~) ( ( ( Inner Bank (Deposition)A meander is a winding bend in a river
formed due to erosion on the outer bank and deposition on the inner bank. It
creates fertile floodplains suitable for agriculture and settlements.
Delta
River | | \ | / \ | / \ | /----------------------- Sea/OceanA delta is a triangular landform formed
by the deposition of sediments at the mouth of a river. It is fertile, supports
farming and fishing, and is rich in biodiversity.
30. Describe the
major tectonic plates of the world and their role in shaping continents and
oceans.
The Earth has seven major tectonic
plates: the Pacific
Plate, North American Plate, South American Plate, Eurasian Plate, African
Plate, Antarctic Plate, and Indo-Australian Plate. These plates
move slowly over the asthenosphere due to convection currents in the mantle.
Their movements create mountains, volcanoes, earthquakes, ocean trenches, and
mid-ocean ridges. For example, the collision of the Indo-Australian Plate
with the Eurasian
Plate formed the Himalayas. Divergent movement forms new ocean
floors, while transform movement causes earthquakes. Plate tectonics explains
the present arrangement of continents and oceans and the continuous reshaping
of the Earth's surface.
Section D:
Assertion–Reason Questions (20)
Directions:
Each question below consists of an Assertion (A) and a Reason (R). Choose the
correct option:
(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.
Q1.
Assertion (A): The
Himalaya were formed due to the collision of two continental plates.
Reason (R): When
continental plates collide, they form fold mountains.
Answer: (a)
Both A and R are true, and R is the correct explanation of A.
Q2.
Assertion (A): The
Mid-Atlantic Ridge is an example of a convergent boundary.
Reason (R): At convergent
boundaries, plates move towards each other.
Answer: (d)
A is false, but R is true.
Q3.
Assertion (A): Erosion
differs from weathering because erosion involves movement of material.
Reason (R): Weathering
only breaks down rocks without moving them.
Answer: (a)
Both A and R are true, and R is the correct explanation of A.
Q4.
Assertion (A): Oceanic
crust is thicker than continental crust.
Reason (R): Continental
crust ranges from 30–40 km while oceanic crust is only 5–7 km thick.
Answer: (d)
A is false, but R is true.
Q5.
Assertion (A): The San
Andreas Fault causes frequent volcanic eruptions.
Reason (R): Transform
boundaries mainly cause earthquakes, not volcanic activity.
Answer: (d) A
is false, but R is true.
Q6.
Assertion (A): The Ring of
Fire is located around the Pacific Ocean.
Reason (R): Most
earthquakes and volcanoes occur along plate boundaries.
Answer: (b)
Both A and R are true, but R is not the correct explanation of A.
Q7.
Assertion (A): Deltas are
highly fertile regions.
Reason (R): Deltas are
formed by deposition of rich alluvial soil at the mouth of rivers.
Answer: (a)
Both A and R are true, and R is the correct explanation of A.
Q8.
Assertion (A): Waterfalls
form only in the lower course of rivers.
Reason (R): Waterfalls
occur where hard rocks resist erosion while softer rocks below are worn away.
Answer: (d)
A is false, but R is true.
Q9.
Assertion (A): Meanders
are formed due to lateral erosion and deposition of sediments.
Reason (R): Meanders help
support agriculture and settlement due to fertile soil deposits.
Answer: (b)
Both A and R are true, but R is not the correct explanation of A.
Q10.
Assertion (A): Glacial
erosion forms U-shaped valleys.
Reason (R): Rivers erode
land to form V-shaped valleys.
Answer: (b)
Both A and R are true, but R is not the correct explanation of A.
Q11.
Assertion (A): Terminal
moraines mark the furthest advance of a glacier.
Reason (R): Moraines are
deposits of till carried and left behind by glaciers.
Answer: (a)
Both A and R are true, and R is the correct explanation of A.
Q12.
Assertion (A): Fjords are
formed when the sea floods glacial valleys.
Reason (R): Fjords are
deep, narrow inlets found in glaciated coastal regions.
Answer: (a)
Both A and R are true, and R is the correct explanation of A.
Q13.
Assertion (A): Barchan
dunes are crescent-shaped.
Reason (R): Barchan dunes
form in areas with abundant sand and multiple wind directions.
Answer: (c)
A is true, but R is false.
Q14.
Assertion (A): Karst
topography develops in areas of limestone or soluble rocks.
Reason (R): Chemical
weathering and erosion dissolve limestone to create caves and sinkholes.
Answer: (a)
Both A and R are true, and R is the correct explanation of A.
Q15.
Assertion (A): Stalactites
are icicle-shaped formations hanging from the ceiling of caves.
Reason (R): Stalagmites
are formations rising from the floor of caves.
Answer: (b)
Both A and R are true, but R is not the correct explanation of A.
Q16.
Assertion (A): Landslides
are caused only by natural factors.
Reason (R): Human
activities such as deforestation and mining also increase landslide risk.
Answer: (d)
A is false, but R is true.
Q17.
Assertion (A): Avalanches
occur due to sudden instability of snow on steep slopes.
Reason (R): A rise in
temperature can cause partial melting of snow, reducing friction and triggering
avalanches.
Answer: (a)
Both A and R are true, and R is the correct explanation of A.
Q18.
Assertion (A): GLOFs are
caused by the sudden collapse of natural dams holding glacial lake water.
Reason (R): Rising
temperatures cause glaciers to melt rapidly, increasing pressure on glacial
lake dams.
Answer: (a)
Both A and R are true, and R is the correct explanation of A.
Q19.
Assertion (A): Dust storms
mainly occur in coastal, humid regions.
Reason (R): Dust storms
are caused by strong winds lifting loose, dry soil and sand.
Answer: (d)
A is false, but R is true.
Q20.
Assertion (A): Weathering
and erosion together help shape landforms such as caves, cliffs, and deltas.
Reason (R): Weathering
breaks down rocks while erosion transports the broken material to new
locations.
Answer: (a)
Both A and R are true, and R is the correct explanation of A.
***********