Chapter 2 Shaping of Earth’s Surface
(NCERT)
Questions
& Answers
1. What is a
landform?
Answer: A
landform is a natural feature on the Earth's surface formed by weathering,
erosion, deposition, and movement of the Earth's crust.
2. What is the
difference between weathering and erosion?
Answer: Weathering
breaks rocks into smaller pieces without moving them. Erosion carries the
broken material from one place to another.
3. What are the
sources of energy that are required to cause movements associated with the
internal forces of the Earth?
Answer: Heat from
the Earth's interior. This is the primary source. It causes convection currents
in the mantle, which move tectonic plates and lead to earthquakes, volcanic
eruptions, and mountain building.
4. Who proposed the
theory of plate tectonics?
Answer: W.J.
Morgan proposed the theory of plate tectonics.
5. Which ancient text
contains a dedicated section on earthquakes, and who wrote it?
Answer: The Bṛihatsaṁhitā
contains a dedicated section on earthquakes, written by Varāhamihira.
6. What are the three
types of weathering?
Answer: Physical
weathering Chemical weathering biological weathering
7. What are the three
main layers of the Earth?
Answer: The
crust, mantle, and core.
8. According to
Varāhamihira, what signs could indicate an impending earthquake?
Answer: Changes
in wind, rain, clouds, animal behaviour, and planetary alignments could signal
them.
9. How does erosion
affect farmers?
Answer: Erosion
removes fertile topsoil, which can reduce crop production.
10. What is the
lithosphere?
Answer: The rigid
outer layer consisting of the crust and upper mantle.
11. What are the four
elemental forces to which Varāhamihira attributed earthquakes?
Answer: The four
elemental forces are Vāyu (wind), Agni (fire), Indra (heaven/thunder), and Varuṇa
(water).
12. What is
contouring?
Answer: Contouring
involves digging trenches along the contour lines of a hillside to slow and
hold rainwater and reduce soil erosion.
13. What is the
asthenosphere?
Answer: A
semi-molten layer beneath the lithosphere that allows tectonic plates to move.
14. How did
Varāhamihira categorize four elemental forces in relation to earthquakes?
Answer: He linked
each elemental force to specific constellations and regions.
15. What is
terracing?
Answer: Terracing
creates a series of level or gently sloping steps on a hillside to prevent soil
erosion.
16. Name the three
types of tectonic plates.
Answer: Continental,
oceanic, and mixed plates.
17. What does this
ancient approach to understanding earthquakes reflect about early Indian
science?
Answer: It
reflects an early attempt to blend observations with cosmological reasoning and
physical phenomena in India.
18. Name the main
agents of gradation.
Answer: Running
water, glaciers, wind, waves and groundwater.
19. What causes
tectonic plates to move?
Answer: Convection
currents in the mantle caused by heat from the Earth's core.
20. How are meanders
formed?
Answer: Rivers
erode their outer banks and deposit sediments on their inner banks, gradually
forming winding curves.
21. What are the
three types of plate boundaries?
Answer: Convergent,
divergent, and transform boundaries.
22. Why are deltas
important?
Answer: Deltas
have fertile soil and support agriculture, fishing, settlements and trade.
23. What shapes the
Earth’s surface? What is plate tectonics?
Answer: Earth’s
surface is shaped by internal forces such as plate tectonics, earthquakes and
volcanoes, and external forces such as weathering, erosion and deposition.
Plate tectonics is the theory that Earth’s lithosphere is divided into moving
plates that interact to form mountains, oceans, earthquakes and volcanoes.
24. What forms when
two continental plates collide?
Answer: Fold
mountains such as the Himalaya.
25. What are the
effects of plate movement?
Answer: Plate
movement causes earthquakes, volcanic eruptions, mountain building, formation
of ocean trenches and mid-ocean ridges, and the creation and breakup of
continents.
26. What is
weathering?
Answer: Weathering
is the breaking down of rocks into smaller pieces. Does weathering involve
movement?
27. Name the three
types of weathering.
Answer: Physical,
chemical and biological weathering.
28. What is erosion?
Answer: Erosion
is the wearing away and movement of soil and rocks.
29. Name two agents
of erosion.
Answer: Water and
wind.
30. What is a
meander?
Answer: A meander
is a winding curve or bend in a river.
31. What is a delta?
Answer: A delta
is a landform formed by deposition of sediments at a river's mouth.
32. What is a
waterfall?
Answer: It is a
river flowing over a steep drop or cliff.
33. What is a
moraine?
Answer: A moraine
is material deposited by a glacier.
34. What is a GLOF?
Answer: GLOF
means Glacial Lake Outburst Flood.
35. What are dunes?
Answer: Dunes are
hills or ridges of sand formed by wind.
36. What is a
landslide?
Answer: It is the
sudden movement of soil and rocks down a slope.
37. Name two coastal
landforms.
Answer: Beaches
and sea cliffs.
38. What is a
sinkhole?
Answer: It is a
depression formed when the ground collapses into an underground cavity.
39. Name two agents
of gradation.
Answer: Running
water and glacier
40. How do glaciers
shape the land?
Answer: Glaciers
scrape, erode and carry materials, forming landforms such as U-shaped valleys,
cirques and fjords.
41. What is the Ring
of Fire?
Answer: An area
around the Pacific Ocean where most earthquakes and volcanoes occur.
42. How are landforms
formed and how are they classified?
Answer: Landforms
are formed by tectonic activity and by weathering, erosion and deposition. They
are commonly classified as mountains, plateaus, plains, valleys, hills,
deserts, coastal landforms and river landforms.
43. What causes dust
storms?
Answer: Strong
winds lift loose, dry soil and sand. Drought, low rainfall and sparse
vegetation make dust storms more likely.
44. Name India’s only
mud volcano?
Answer: India’s
only mud volcano is in Baratang in the Andaman and Nicobar Islands.
Long
Questions & Answers
1. What were
earthquakes known as in early times, and what does the term mean?
Answer: In early
times, earthquakes were known as ‘bhūkampa’, which means the shaking of the
Earth.
2. Which ancient text
contains a dedicated section on earthquakes, and who wrote it?
Answer: The Bṛihatsaṁhitā
contains a dedicated section on earthquakes, written by Varāhamihira.
3. According to
Varāhamihira, what signs could indicate an impending earthquake?
Answer: Changes
in wind, rain, clouds, animal behaviour, and planetary alignments could signal
them.
4. How are humans and
other living beings connected to these landforms?
Answer: Humans,
plants and animals depend on landforms for food, water, shelter, farming,
transport and natural resources. Different landforms support different
ecosystems, occupations and settlements.
5. What were
earthquakes known as in early times, and what does the term mean?
Answer: In early
times, earthquakes were known as ‘bhūkampa’, which means the shaking of the
Earth.
6. How do disasters
associated with different landforms impact human lives?
Answer: Disasters
such as earthquakes, volcanic eruptions, landslides, floods and tsunamis can
damage homes, infrastructure and farmland, cause injuries and loss of life,
disrupt livelihoods and affect the environment.
7. Explain the
different types of weathering.
Answer: Weathering
is the process of breaking down rocks on the Earth's surface. It does not
involve the movement of broken material. There are three main types: Physical
weathering: Rocks break into smaller pieces due to temperature changes, frost
or wind. Chemical weathering: Minerals in rocks change through reactions with
water, air or acids. Biological weathering: Plants, animals and microorganisms
break down rocks. For example, plant roots can grow into cracks and split
rocks. Weathering helps shape the Earth's surface and contributes to soil
formation.
8. Explain the causes
of tectonic plate movement.
Answer: The
movement of tectonic plates is caused by convection currents in the Earth's
mantle. Heat from the Earth's core causes molten rock in the mantle to rise,
while cooler material sinks. This continuous circulation creates convection
currents that push and pull the tectonic plates in different directions. As the
plates move, they interact at their boundaries, resulting in the formation of
mountains, volcanoes, earthquakes, and other landforms.
9. How are
deforestation and erosion associated with each other?
Answer: Deforestation
removes trees and other vegetation that help hold soil together. Without
vegetation, soil becomes loose and exposed to wind and water. This increases
soil erosion. The chapter also notes that sparse vegetation caused by
deforestation can leave land exposed and contribute to dust storms.
10. What
precautionary measures will you take if you are staying in an earthquake-prone
region?
Answer: Drop,
cover, and hold on: “Drop down to the ground so the earthquake doesn't knock
you down.” under a sturdy desk or table. Stay indoors: Avoid running outside or
standing near glass windows and heavy objects. Protect in bed: Stay in bed and
cover your head with a pillow if you are sleeping
11. Explain how
landforms and natural processes affect human life.
Answer: Landforms
influence human settlements, agriculture, trade, transport and culture. Rivers
and fertile plains supported early agricultural societies and cities. Mountains
acted as barriers and protectors, while mountain passes encouraged cultural
exchange. Coasts and harbours supported trade and travel. Landforms also
provide resources and tourism opportunities. At the same time, some landforms
and processes can cause disasters such as landslides, avalanches, GLOFs and
floods.
12. What are
landforms? Explain how they are formed.
Answer: Landforms
are natural features found on the Earth's surface. They are formed through
processes such as weathering, erosion, deposition, and the movement of the
Earth's crust. Examples include mountains, valleys, plateaus, plains, deserts,
and coastal features. The movement of tectonic plates also plays an important
role in creating many of these landforms through mountain building, volcanic
eruptions, and earthquakes
13. Describe the
three types of plate boundaries and the landforms they create.
Answer: There are
three main types of plate boundaries: Convergent Boundary: Two plates move
toward each other. Continental collisions form fold mountains like the
Himalaya, while oceanic-continental collisions cause volcanic activity and
earthquakes. Divergent Boundary: Two plates move apart, allowing magma to
rise and create new crust. This forms mid-ocean ridges, such as the
Mid-Atlantic Ridge. Transform Boundary: Two plates slide past one another
without creating or destroying crust. This movement mainly causes earthquakes,
such as along the San Andreas Fault. Each type of boundary contributes to the
continuous reshaping of the Earth's surface.
14. Explain the
importance of plate tectonics in shaping the Earth's surface.
Answer: Plate
tectonics is one of the most important geological processes because it
constantly reshapes the Earth's surface. The movement of tectonic plates forms
mountains, valleys, volcanoes, ocean basins, and other landforms. It also
explains the distribution of continents and oceans. Most earthquakes and
volcanoes occur along plate boundaries, especially around the Pacific Ocean,
known as the Ring of Fire. Thus, plate tectonics helps us understand many
natural processes occurring on Earth.
15. Explain the
difference between the lithosphere and the asthenosphere.
Answer: The
lithosphere is the rigid outer layer of the Earth made up of the crust and the
uppermost part of the mantle. It is broken into tectonic plates. The
asthenosphere lies beneath the lithosphere and is a hot, semi-molten layer of
partially melted rock. Its soft and mobile nature allows the tectonic plates
above it to move slowly. This movement is responsible for many geological
activities on Earth.
16. Why do
earthquakes and volcanoes occur mainly along plate boundaries?
Answer: Earthquakes
and volcanoes occur mainly along plate boundaries because this is where
tectonic plates interact. At convergent boundaries, plates collide, creating
intense pressure, earthquakes, and volcanic eruptions. At divergent boundaries,
magma rises through gaps to form new crust and volcanoes. At transform
boundaries, plates slide past one another, causing earthquakes due to friction.
Therefore, plate boundaries are the most active geological zones on Earth.
17. Explain how
rivers form different landforms.
Answer: Rivers
shape land through erosion, transportation and deposition. In the upper course,
rivers form V-shaped valleys, waterfalls and rapids. In the middle course,
rivers form meanders, oxbow lakes and floodplains. In the lower course, rivers
deposit sediments and form deltas, levees and alluvial fans. These landforms
are important for agriculture, settlements and ecosystems.
18. Explain the
different landforms formed by coastal erosion.
Answer: Waves,
tides and currents wear away coastal land. This process is called coastal
erosion. It forms: Cliffs – steep rock faces formed when waves wear away the
coast. Wave-cut platforms – flat areas left as cliffs retreat. Caves – formed
when waves erode weak parts of rocks. Arches – formed when caves meet through a
headland. Stacks – isolated rock pillars left after arches collapse. These
landforms also influence tourism and the need for coastal protection.
19. Why and where do
earthquakes occur frequently? Is it possible to predict earthquakes?
Answer: Ring of
Fire and Boundaries: Most quakes happen along active edges where these plates
meet, such as the Pacific Ring of Fire or major fault systems like the San
Andreas Fault and Alpine-Himalayan belt According to the Survey, scientists
cannot predict the exact time, date, and magnitude of any single upcoming.
Instead of prediction, modern networks offer brief early warning alerts lasting
from seconds to minutes after a quake starts to help people take cover
20. What are tectonic
plates? Describe their types with examples.
Answer: Tectonic
plates are huge slabs of solid rock that make up the Earth's lithosphere. They
move slowly, usually a few centimetres each year. There are three types of
tectonic plates: Continental plates, which carry continents. Oceanic plates,
which carry ocean floors. Mixed plates, which contain both continental and
oceanic crust. Some major tectonic plates include the Pacific Plate, Eurasian
Plate, African Plate, North American Plate, South American Plate,
Indo-Australian Plate, and Antarctic Plate. Their movement shapes the Earth's
surface and causes many geological events.
21. Explain the
causes of landslides.
Answer: Landslides
occur when slopes become unstable. Heavy rainfall increases the weight of soil
and reduces friction. Earthquakes and volcanic eruptions can also trigger
landslides. Steep slopes and loose rocks increase the risk. Human activities
such as deforestation, mining, road construction and unplanned construction can
also make slopes unstable. Poor drainage and improper land use may further
increase the risk.
22. Write a detailed
note on the significance of studying plate tectonics and landforms.
Answer: Studying
plate tectonics and landforms helps us understand how the Earth's surface
changes over time. Plate tectonics explains the movement of tectonic plates and
the formation of mountains, volcanoes, valleys, and ocean basins. It also helps
explain natural events such as earthquakes and volcanic eruptions. Landforms,
created by weathering, erosion, deposition, and crustal movement, reveal the
dynamic nature of the Earth. This knowledge is valuable for understanding
natural hazards, Earth's history, and the development of continents and oceans.
23. Describe the
structure of the Earth.
Answer: The Earth
has three main layers: the crust, mantle, and core. The crust is the thin
outermost layer where humans live. Below it lies the mantle, which is thick and
hot. The upper part of the mantle and the crust together form the lithosphere,
which is divided into tectonic plates. Beneath the lithosphere is the
semi-molten asthenosphere that allows these plates to move. The core consists
of two parts: the outer core, which is a liquid layer mainly made of iron and
nickel, and the inner core, which is a solid, extremely hot, and dense metal
ball.
24. Relate various
physiographic divisions of India with various endogenic forces responsible for
their origin.
Answer: India's
major physiographic divisions—the Himalayas, the Peninsular Plateau, and the
Northern Plains—are directly linked to internal or endogenic forces like plate
collision, volcanic activity, and tectonic subsidence.
Himalayan Mountains:
Convergent Plate
Movement: Formed by the collision of the Indian Plate and the Eurasian Plate.
Folding and Uplift: “When these two continental plates collided, the land was
pushed upward, forming these young fold mountains,”
Peninsular Plateau:
Developed through ancient volcanic activity and stable block faulting. Ancient
Landmass: “Plateaus, like the Deccan Plateau, developed through volcanic
activity,” explaining its hard igneous rock base
Northern Plains: Subsidence and Faulting: Formed over a
large structural depression or basin created in front of the advancing
Himalayas. Tectonic Sinking: “The base was created by the sinking (subsidence)
of the land due to faulting,” which was later filled by river sediments
