.

Test is part of Rau’s IAS Test series for Preliminary Exam 202 3

Test ID
GENERAL STUDIES (PAPER–I)
1023

WORLD GEOGRAPHY-1
Time Allowed: 1 Hour Maximum Marks: 100

INSTRUCTIONS

1. IMMEDIATELY AFTER THE COMMENCEMENT OF THE EXAMINATION, YOU SHOULD CHECK

THAT THIS TEST BOOKLET DOES NOT HAVE ANY UNPRINTED OR TORN or MISSING PAGES OR
ITEMS, ETC. IF SO, GET IT REPLACED BY A COMPLETE TEST BOOKLET.

2. This Test Booklet contains 50 items (questions). Each item is printed in English Only. Each item
comprises four responses (answers). You will select the response which you want to mark on the
Answer Sheet. In case you feel that there is more than one correct response, mark the response
which you consider the best. In any case, choose ONLY ONE response for each item.

3. You have to mark all your responses ONLY on the separate Answer Sheet (OMR sheet) provided.
Read the directions in the Answer Sheet.

4. All items carry equal marks.

5. Before you proceed to mark in the Answer Sheet the response to various items in the Test booklet,
you have to fill in some particulars in the Answer Sheet as per instructions contained therein.

6. After you have completed filling in all your responses on the Answer Sheet and the examination has
concluded, you should hand over to the Invigilator only the Answer Sheet. You are permitted to
take away with you the Test Booklet.

7. Penalty for wrong answers:

THERE WILL BE PENALTY FOR WRONG ANSWERS MARKED BY A CANDIDATE IN THE

OBJECTIVE TYPE QUESTION PAPERS.

(i) There are four alternatives for the answer to every question. For each question for which a
wrong answer has been given by the candidate, one-third of the marks assigned to that
question will be deducted as penalty.

(ii) If a candidate gives more than one answer, it will be treated as a wrong answer even if one of
the given answers happens to be correct and there will be same penalty as above to that
question.

(iii) If a question is left blank, i.e., no answer is given by the candidate, there will be no penalty for
that question.

This test is part of Rau’s IAS Test series for Preliminary Exam 202 3
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1. Which of the following could be the possible 2. The size of a planet increases as the
reasons for the formation of the planets in distance from the Sun increases.
the Solar System? 3. All gaseous planets are called Jovian
1. Approaching star. planets.
2. Pre-existing rock structures. 4. The first four planets from the Sun have
3. Rotating disc of the clouds. terrestrial structure, due to the
4. Solar Nebula of hydrogen and helium. presence of the solar winds.
Select the correct answer using the code Which of the statements given above are
given below: correct?
(a) 1, 3 and 4 only (a) 1, 3 and 4 only
(b) 1, 2 and 4 only (b) 2 and 4 only
(c) 2, 3 and 4 only (c) 3 and 4 only
(d) 1 and 4 only (d) 1 and 4 only

2. With reference to the Big Bang Theory, 5. The Moon is the only natural satellite of
consider the following statements: planet Earth. In this reference, consider the
1. Universal galaxies are moving away following statements:
from each other, but not increasing in 1. The origin of the Moon is believed to be
their size. from the Earth itself.
2. The entire Universe was born out of a 2. The Moon is larger than the known
single atom of infinite energy, density dwarf planets in our Solar System.
and temperature.
3. The Moon is responsible for the
Which of the statements given above is/are geological developments on the Earth.
correct?
Which of the statements given above is/are
(a) 1 only correct?
(b) 2 only (a) 1 and 3 only
(c) Both 1 and 2
(b) 2 and 3 only
(d) Neither 1 nor 2
(c) 3 only
(d) 1, 2 and 3
3. Which of the following would be the
contributing factors for the formation of a
6. In terms of the radius of the planets in our
star?
Solar System, which of the following
1. Pre-existing nebula cloud.
planets have size smaller than the Earth?
2. High gravitational force.
1. Uranus
3. Fusion reaction.
2. Venus
Select the correct answer using the code
3. Mars
given below:
4. Mercury
(a) 1 and 2 only
(b) 2 and 3 only 5. Neptune

(c) 1 and 3 only Select the correct answer using the code
given below:
(d) 1, 2 and 3
(a) 1, 2 and 3 only
(b) 2, 3, 4 and 5 only
4. With reference to our Solar System,
consider the following statements: (c) 1, 3, 4 and 5 only
1. All planets have natural satellite, (d) 2, 3 and 4 only
however in different numbers.

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7. Consider the following pairs: 10. With reference to the earthquake waves,
Geological Time Life/Major Events consider the following statements:
Scale 1. The first set of waves to generate after
an earthquake is the surface waves on
Archean Presence of algae.
the upper surface of the lithosphere.
Carboniferous Rise of the first
2. Within the body waves, the secondary
reptile.
waves cannot travel through the liquid
Palaeocene Rise of the small state of matter.
mammals. 3. The primary waves are the last to be
Holocene Rise of the modern observed after the earthquake.
man. Which of the statements given above is/are
How many pairs given above is/are correct?
correctly matched? (a) 1 and 2 only
(a) Only one pair (b) 2 only
(b) Only two pairs (c) 3 only
(c) Only three pairs (d) 1, 2 and 3
(d) All four pairs
11. With reference to the propagation of the
8. In terms of sources, which of the following earthquake waves (P-waves and S-waves),
are the indirect sources to know about the consider the following statements:
interior of the Earth? 1. The P-waves vibrate parallel to the
1. Mining/drilling of the minerals direction of the waves.
2. The Earth-reaching meteors 2. The S-waves vibrate perpendicular to
the wave direction in the vertical plane.
3. Gravitational Force
3. Both waves create density differences in
4. Magnetic field
the material leading to stretching and
5. Seismic activity
squeezing of the material.
Select the correct answer using the code
Which of the statements given above is/are
given below:
incorrect?
(a) 1, 2, 3 and 4 only
(a) 1 only
(b) 2, 3, 4 and 5 only
(b) 2 only
(c) 1, 3 and 5 only
(c) 3 only
(d) 2, 4 and 5 only
(d) 1 and 3 only

9. Consider the following statements about

12. Which of the following defines the concept
earthquakes:
of “shadow zone of earthquake”?
1. The point where the energy is released
(a) It is an area where the earthquake
is called the epicentre of an earthquake.
waves are not reported.
2. The point on the surface, nearest to the
(b) It is an area where the secondary waves
epicentre, is called the hypocentre.
are not reported.
Which of the statements given above is/are
(c) It is an area where the primary waves
correct?
are not reported.
(a) 1 only
(d) It is an area where the surface waves
(b) 2 only are not reported.
(c) Both 1 and 2
(d) Neither 1 nor 2

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13. With respect to the “Mass Movements”, 16. Consider the following statements:
consider the following statements: 1. A gorge is a deep valley with very steep
1. Weathering is a pre-requisite for mass to straight sides.
movement. 2. Canyon is almost equal in width at its
2. The mass movements are aided by top, as well as its bottom.
gravity and no geomorphic agents, like 3. Canyons commonly form in horizontal
running water and glaciers. bedded sedimentary rocks and gorges
Which of the statements given above is/are form in hard rocks.
correct? Which of the statements given above are
correct?
(a) 1 only
(a) 1 and 2 only
(b) 2 only
(b) 2 and 3 only
(c) Both 1 and 2
(c) 1 and 3 only
(d) Neither 1 nor 2
(d) 1, 2 and 3

14. With respect to “Landslides”, consider the

17. Consider the followings statements:
following statements:
1. Meandering courses over floodplains
1. They are relatively rapid and perceptible
and delta-plains, where stream
movements.
gradients are very gentle, are called
2. The materials involved are relatively ‘Entrenched Meanders’.
wet. 2. River terraces are the result due to
3. The size and shape of the detached vertical erosion by the stream into its
mass depend on the nature of own depositional floodplain.
discontinuities in the rock. Which of the statements given above is/are
Which of the statements given above is/are correct?
correct? (a) 1 only
(a) 1 only (b) 2 only
(b) 1 and 2 only (c) Both 1 and 2
(c) 2 and 3 only (d) Neither 1 nor 2
(d) 1 and 3 only
18. Consider the following statements:
15. Consider the following statements: 1. The floodplain above a river’s bank is an
1. Fluvial erosional landforms are frequent active floodplain.
with low residual hills, known as the 2. Natural levees are low, linear and
monadnocks. parallel ridges of coarse deposits along
the banks of the rivers.
2. A peneplain is a low-relief plain which is
formed as a result of stream deposition. 3. Point bars are found on the concave
side of the meanders of large rivers.
Which of the statements given above is/are
Which of the statements given above are
correct?
correct?
(a) 1 only
(a) 1 and 2 only
(b) 2 only
(b) 2 and 3 only
(c) Both 1 and 2
(c) 1 and 3 only
(d) Neither 1 nor 2
(d) 1, 2 and 3

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19. With respect to “Meanders”, consider the 22. With respect to the “Glacier Landforms”,
following statements: consider the following statements:
1. It is a loop-like channel pattern 1. Cirques are the most common
developed over flood and delta plains.
depositional landforms in glaciated
2. The outer bend of the meanders has a mountains.
concave slope.
2. Cirque is deep, long and wide trough or
3. The inner side of the meanders is
characterized by intensive erosion. basin with very steep concave to
vertically dropping high walls at its
Which of the statements given above is/are
head, as well as sides.
correct?
(a) 1 only 3. If three or more radiating glaciers cut
(b) 1 and 2 only headward until their cirques meet, high,
(c) 2 and 3 only sharp pointed and steep-sided peaks,
(d) 1, 2 and 3 called horns, form.

Which of the statements given above are

20. Which of the following are the features of correct?
the Limestone Topography? (a) 1 and 2 only
1. Swallow holes
(b) 2 and 3 only
2. Sinkholes
3. Lapies (c) 1 and 3 only
4. Uvala (d) 1, 2 and 3
Select the correct answer using the code
given below:
(a) 2 and 3 only 23. Which of the following statements are
(b) 1, 2 and 3 only correct regarding the plate tectonic
boundaries?
(c) 1, 3 and 4 only
(d) 1, 2, 3 and 4 1. Divergent boundary is the one where
two plates move away from each other,
21. Consider the following statements: resulting in the destruction of the crust.

1. Stalactite is an upward-growing 2. Where the crust is destroyed, as one

mound of mineral deposits that have plate dived under another is known as
precipitated from water dripping onto Convergent boundary.
the floor of a cave.
3. Transform boundary is the one where
2. Stalagmite is an icicle-shaped formation
the crust is neither produced nor
that hangs from the ceiling of a cave.
destroyed, as here the plates slide
3. The stalagmite and stalactites
horizontally past each other.
eventually fuse to give rise to columns
and pillars of different diameters. Select the correct answer using the code
Which of the statements given above is/are given below:
correct? (a) 1 and 2 only
(a) 3 only
(b) 2 and 3 only
(b) 1 and 2 only
(c) 2 and 3 only (c) 1 and 3 only

(d) 1, 2 and 3 (d) 1, 2 and 3

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24. Which of the following statements is/are Select the correct answer using the code
correct regarding the movement of the given below:
Indian Plate? (a) 1 and 2 only
1. During the movement of the Indian (b) 1 only
Plate towards the Eurasian Plate, (c) 1 and 3 only
Deccan Traps got formed due to (d) 1, 2 and 3
outpouring of lava.
2. India collided with Asia about 40-50 27. Which of the following statements are
million years ago, causing rapid uplift of correct with respect to metamorphism and
metamorphic rocks?
the Himalayas.
1. Metamorphism is a process by which
Select the correct answer using the code
already consolidated rocks undergo re-
given below: crystallisation and reorganisation of
(a) 1 only materials within the original rocks.
(b) 2 only 2. In dynamic metamorphism, mechanical
(c) Both 1 and 2 disruption and reorganisation of the
original minerals take place with
(d) Neither 1 nor 2
appreciable chemical changes and
recrystallization.
25. Which of the following statements is/are 3. These rocks form under the action of
correct regarding petrology? pressure, volume and temperature
1. Petrology is the branch of geology that (PVT) changes.
studies rocks and the conditions under 4. When rocks grains or minerals get
arranged in layers or lines, such an
which they form.
arrangement of minerals or grains in
2. It is concerned with all three major metamorphic rocks is called foliation or
types of rocks – igneous, metamorphic lineation.
and sedimentary. Select the correct answer using the code
Select the correct answer using the code given below:
given below: (a) 1, 2 and 3 only
(a) 1 only (b) 1, 3 and 4 only
(b) 2 only (c) 2, 3 and 4 only
(c) Both 1 and 2 (d) 1, 2, 3 and 4

(d) Neither 1 nor 2

28. Consider the following pairs with respect to
sedimentary rocks:
26. Which of the following statements is/are
S.N. Sedimentary rock Example
correct regarding the igneous rocks? group
1. When magma, in its upward movement,
1. Mechanically formed Sandstone
cools and turns into solid form, it is
2. Chemically formed Coal
called igneous rock.
3. Organically formed Chert
2. While formation of the igneous rocks, if
molten material is cooled slowly at great Which of the pairs given above is/are
depths, mineral grains may be small correctly matched?
and smooth. (a) 1 only
3. While formation of the igneous rocks, (b) 2 only
sudden cooling (at the surface) results (c) 2 and 3 only
in very large mineral grains. (d) None of the above.

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29. Which of the following statements are 32. Consider the following statements:
correct with respect to rock cycle? 1. The oceanic crust is thinner as
1. Igneous rocks can lead to the formation compared to the continental crust.
of sedimentary, as well as metamorphic 2. The continental crust is thinner in the
rocks. areas of major mountain systems.

2. Metamorphic rocks can be formed only Which of the statements given above is/are
correct?
from igneous rocks.
(a) 1 only
3. Sedimentary rocks can be formed from
(b) 2 only
igneous, as well as metamorphic rocks
(c) Both 1 and 2
Select the correct answer using the code
(d) Neither 1 nor 2
given below:
(a) 1 and 2 only
33. With reference to ‘mantle’, consider the
(b) 2 and 3 only
following statements:
(c) 1 and 3 only 1. The lower portion of the mantle is called
(d) 1, 2 and 3 asthenosphere.
2. It is the main source of magma that
30. Which of the following processes are parts comes to the surface during volcanic
of diastrophism? eruptions.
3. The crust and the upper-most part of
1. Orogenic processes
the mantle together are called
2. Epeirogenic processes
lithosphere.
3. Minor earthquakes Which of the statements given above are
4. Plate tectonics correct?
Select the correct answer using the code (a) 1 and 2 only
given below: (b) 2 and 3 only
(a) 1, 2 and 3 only (c) 1 and 3 only
(b) 2, 3 and 4 only (d) 1, 2 and 3
(c) 1, 3 and 4 only
(d) 1, 2, 3 and 4 34. Consider the following statements:
1. The Moho’s Discontinuity forms the
boundary between the mantle and the
31. Which of the following statements is/are
core.
correct regarding weathering?
2. The outer core is in liquid state, while
1. Climate directly affects the type, as well the inner core is in solid state.
as the depth of weathering. 3. The core is made up of very heavy
2. Solution, carbonation and hydration are material, mostly constituted by silicon
part of chemical weathering. and copper.
Select the correct answer using the code Which of the statements given above are
given below: incorrect?
(a) 1 only (a) 1 and 2 only

(b) 2 only (b) 2 and 3 only

(c) 1 and 3 only
(c) Both 1 and 2
(d) 1, 2 and 3
(d) Neither 1 nor 2

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35. Consider the following statements: 38. With reference to the concept of
1. Shield volcanoes are very steep due to Continental Drift, consider the following
the presence of viscous lava. statements:
2. Composite volcanoes often result in 1. Alfred Wegener propounded the
explosive eruptions. Continental Drift Theory.
3. Calderas are the most explosive 2. Initially, super continent Pangaea broke
volcanoes of the Earth. into two parts, in which Laurasia made
Which of the statements given above are the southern component.
correct? Which of the statements given above is/are
(a) 1 and 2 only correct?
(b) 2 and 3 only (a) 1 only
(c) 1 and 3 only (b) 2 only
(d) 1, 2 and 3 (c) Both 1 and 2
(d) Neither 1 nor 2
36. With reference to the intrusive volcanic
landforms, consider the following
39. Consider the following statements:
statements:
1. The foci of the earthquake in the areas
1. Dykes are the landforms that solidify
of mid-oceanic ridges are at deeper
parallel to the ground and form a
depths.
concave saucer shape.
2. The near horizontal bodies of the 2. The ‘Rim of the Pacific’ is due to the
intrusive igneous rocks are called sills existence of active volcanoes.
or sheets. Which of the statements given above is/are
3. Lacoliths are large dome-shaped correct?
intrusive bodies with a level base and (a) 1 only
connected by a pipe-like conduit from (b) 2 only
below. (c) Both 1 and 2
Which of the statements given above are
(d) Neither 1 nor 2
correct?
(a) 1 and 2 only
40. Which of the following facts supported the
(b) 2 and 3 only
‘Concept of Sea Floor Spreading’?
(c) 1 and 3 only
1. Rocks closer to the mid-oceanic ridges
(d) 1, 2 and 3
have reverse polarity and are the oldest.
2. The ocean crust rocks are much
37. Consider the following statements:
younger than the continental rocks.
1. Plutonic rocks are igneous rocks that
3. The sediments on the ocean floor are
develop due to the cooling of lava inside
unexpectedly very thick.
the crust.
4. All along the mid-oceanic ridges,
2. Batholiths appear on the surface only
volcanic eruptions are common.
after the denudational processes
remove the overlying materials. Select the correct answer using the code
Which of the statements given above is/are given below:
correct? (a) 1, 2 and 3 only
(a) 1 only (b) 2 and 4 only
(b) 2 only (c) 3 and 4 only
(c) Both 1 and 2 (d) 1 and 3 only
(d) Neither 1 nor 2

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41. With reference to the lithospheric plates, Select the correct answer using the code
consider the following pairs: given below:
S.N. Name Type of Plate (a) 1 only

1. Nazca Major (b) 2 only

(c) Both 1 and 2
2. Cocos Minor
(d) Neither 1 nor 2
3. Pacific Major
4. Arabian Minor
44. Which among the following reservoirs has
Which of the pairs given above are correctly the highest volume of water on the Earth’s
matched? surface?
(a) 1 and 2 only (a) Lakes
(b) 1 and 3 only (b) Groundwater
(c) 2 and 3 only (c) Atmosphere
(d) 2, 3 and 4 only (d) Streams and Rivers

42. Which of the following facts serve as 45. Consider the following statements about
‘evidence in support of the Continental Continental Shelf:
Drift’? 1. It is the shallowest part of the ocean
1. The shorelines of Australia and Asia, showing an average gradient of 1° or
facing each other, have a remarkable even less.
and unmistakable match. 2. The average width of continental
2. The Gondwana system of sediments shelves is about 200 km.
from India is known to have its 3. The shelves are almost very narrow
counterparts in six different along the coasts of Chile.
landmasses.
Which of the statements given above is/are
3. The occurrence of rich placer deposits correct?
of gold in the Ghana Coast and the
(a) 1 and 3 only
absolute absence of source rock in the
(b) 2 and 3 only
region.
(c) 1 and 2 only
4. The belt of ancient rocks from the Brazil
Coast matches with those from western (d) 1, 2 and 3
Africa.
Select the correct answer using the code 46. Consider the following statements about
given below: Continental slope:
(a) 1, 2 and 3 only 1. The continental slope connects the
(b) 2, 3 and 4 only continental shelf and the ocean basins.
(c) 3 and 4 only 2. Canyons and trenches are observed in
(d) 1, 2, 3 and 4 this region.
3. The depths vary between 3,000 and
6,000m.
43. Which of the following statements is/are
correct? Which of the statements given above are
1. Exfoliation domes are created due to correct?
successive removal of crust on account (a) 1 and 2 only
of reduced pressure. (b) 2 and 3 only
2. Exfoliation tors are created due to (c) 1 and 3 only
thermal expansion. (d) 1, 2 and 3

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47. Consider the following statements: 49. Consider the following statements:
1. Seamounts are volcanic in origin. 1. Atolls are low islands found in the
2. The Emperor seamount is located in the tropical oceans consisting of coral reefs
Atlantic Ocean. surrounding a central depression.
3. Guyots show evidences of gradual 2. Atoll may be a part of the sea lagoon.
subsidence through stages to become 3. Iceland is a part of the mid- Atlantic
flat topped submerged mountains. Ridge.
Which of the statements given above are Which of the statements given above are
correct? correct?
(a) 1 and 2 only (a) 1 and 2 only
(b) 2 and 3 only (b) 2 and 3 only
(c) 1 and 3 only (c) 1 and 3 only
(d) 1, 2 and 3 (d) 1, 2 and 3

48. Consider the following statements: 50. Consider the following statements:
1. Labrador current raises the 1. The temperature decreases with the
temperature near the eastern coast of increasing depth.
North America and the West Coast of 2. The salinity of water in the surface layer
Europe. of oceans depend mainly on evaporation
2. Gulf Stream lowers the temperature and precipitation.
near the north-east coast of North Which of the statements given above is/are
America. correct?
Which of the statements given above is/are (a) 1 only
correct? (b) 2 only
(a) 1 only (c) Both 1 and 2
(b) 2 only (d) Neither 1 nor 2
(c) Both 1 and 2
(d) Neither 1 nor 2

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Answers &
Explanations
of

TEST ID: 1023

GENERAL STUDIES (PAPER–I)

World Geography-1

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ANSWERS & EXPLANATIONS OF
World Geography-1
GS Paper-I: (1023)

1. Answer: (a) 2. Answer: (c)

Explanation: Explanation:
A large number of hypotheses were put The most popular argument regarding the
forth by different philosophers and origin of the Universe is the Big Bang
scientists regarding the origin of the Earth. Theory. It is also called the ‘Expanding
One of the earlier and popular arguments Universe Hypothesis’. Edwin Hubble, in
was by the German philosopher Immanuel 1920, provided evidence that the Universe
Kant. Mathematician Laplace revised it in is expanding. As the time passes, the
1796. It is known as the Nebular galaxies move further and further apart.
Hypothesis. The hypothesis considered The scientists believe that though the space
that the planets were formed out of a between the galaxies is increasing, the
cloud of material, associated with a observations do not support the expansion
youthful Sun, which was slowly rotating. of the galaxies. So, the balloon example is
Later in 1900, Chamberlin and Moulton only partially correct.
considered that a wandering star The Big Bang Theory considers the
approached the Sun. As a result, a cigar- following stages in the development of
shaped extension of material was the Universe:
separated from the solar surface. As the (i) In the beginning, all matters forming
passing star moved away, the material, the Universe existed in one place in the
separated from the solar surface, form of a “tiny ball” (singular atom),
continued to revolve around the Sun and with an unimaginably small volume,
it slowly condensed into planets. Sir infinite temperature and infinite
James Jeans and later, Sir Harold Jeffreys density.
supported this argument.
(ii) At the Big Bang, the “tiny ball” exploded
At a later date, the arguments considered violently. This led to a huge expansion.
of a companion to the Sun to have been co- It is now generally accepted that the
existing. These arguments are called the event of Big Bang took place 13.7 billion
Binary Theories. In 1950, Otto Schmidt in years before the present. The expansion
Russia and Carl Weizascar in Germany continues even to the present day. As it
somewhat revised the ‘Nebular Hypothesis’, grew, some energy was converted into
though differing in details. They considered matter. There was particularly rapid
that the Sun was surrounded by the Solar expansion within fractions of a second
Nebula, containing mostly the hydrogen after the Bang. Thereafter, the
and helium, along with what may be expansion has slowed down. Within the
termed as dust. The friction and collision first three minutes from the Big Bang
of the particles led to the formation of a event, the first atom began to form.
disk-shaped cloud and the planets were
(iii) Within 3,00,000 years from the Big
formed through the process of accretion.
Bang, the temperature dropped to
However, the scientists in the later period 4,500K (Kelvin) and gave rise to the
took up the problems of the origin of the atomic matter.
Universe, rather than that of just the Earth
or the planets.

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3. Answer: (d) the first four are called ‘Terrestrial’,
Explanation: meaning Earth-like, as they are made up of
Star formation is the process by which rocks and metals, and have relatively high
dense regions within the molecular clouds densities. The rest all four are called
in the interstellar space, sometimes ‘Jovian’ or ‘Gas Giant’ planets. Jovian
referred to as "stellar nurseries" or "star- means Jupiter-like. Most of them are much
forming regions", collapse and form stars. larger than the Terrestrial planets and have
A spiral galaxy, like the Milky Way, thick atmosphere, mostly of helium and
contains stars, stellar remnants and a hydrogen. All the planets were formed in
diffuse interstellar medium (ISM) of gas and the same period, sometime about 4.6
dust. The interstellar medium consists of billion years ago.
10−4 to 106 particles per cm3 and is The difference between the Terrestrial
typically composed of roughly 70% and the Jovian planets can be attributed
hydrogen by mass, with most of the to the following conditions:
remaining gas consisting of helium. This
(i) The Terrestrial planets were formed in
medium has been chemically enriched
the close vicinity of the parent star,
by trace amounts of heavier elements
where it was too warm for the gases to
that were produced and ejected from the
condense to solid particles. The Jovian
stars via the fusion of helium, as they
planets were formed at quite a distant
passed beyond the end of their main
sequence lifetime. Higher density location.
regions of the interstellar medium form (ii) The solar wind was most intense nearer
clouds, or diffuse nebulae, where star the Sun; so, it blew off lots of gas and
formation takes place. dust from the Terrestrial planets. The
In contrast to spirals, an elliptical galaxy solar winds were not all that intense to
loses the cold component of its interstellar cause similar removal of gases from the
medium within roughly a billion years, Jovian planets.
which hinders the galaxy from forming (iii) The Terrestrial planets are smaller and
diffuse nebulae, except through mergers their lower gravity could not hold the
with other galaxies. escaping gases.
In the dense nebulae, where the stars The size of the planets is the largest in
are produced, much of the hydrogen is the middle section (Jupitar and Saturn).
in the molecular (H2) form. So, these
Mercury and Venus do not have any
nebulae are called ‘molecular clouds’.
natural satellites.
Dense molecular filaments, which are
central to the star formation process,
will fragment into gravitationally bound 5. Answer: (d)
cores, most of which will evolve into Explanation:
stars. The Moon is the Earth's only natural
satellite. Together with the Earth, it forms
4. Answer: (c) the Earth–Moon satellite system. It is about
Explanation: one-quarter of the Earth in diameter
Out of the eight planets, Mercury, Venus, (comparable to the width of Australia). In
Earth and Mars are called the ‘inner the Solar System, it is the fifth largest
planets’, as they lie between the Sun and satellite, larger than any of the known
the belt of asteroids. The other four planets dwarf planets and the largest (and most
are called the ‘outer planets’. Alternatively, massive) satellite of a planet, relative to the
planet.

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The Moon is a planetary-mass object that present the depression occupied by the
formed a differentiated rocky body, making Pacific Ocean.
it a satellite planet under the geophysical However, the present scientists do not
definitions of the term. It lacks any accept either of the explanations. It is now
significant atmosphere, hydrosphere or generally believed that the formation of the
magnetic field. Its surface gravity is about Moon, as a satellite of the Earth, is an
one-sixth of the Earth's (0.1654 g). outcome of ‘the giant impact’ or what is
In 1838, Sir George Darwin suggested that described as “the big splat”.
initially the Earth and the Moon formed a The presence of the Moon, as a natural
single rapidly rotating body. The whole satellite, impacts the tidal waves on the
mass became a dumb-bell-shaped body Earth. These tidal waves are responsible for
and eventually it broke. It was also the presence of different geological features
suggested that the material forming the on the coastal regions.
Moon was separated from what we have at

6. Answer: (d)
Explanation:
The Solar System
Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune
Distance* 0.387 0.723 1.000 1.524 5.203 9.539 19.182 30.058
Density@ 5.44 5.245 5.517 3.945 1.33 0.70 1.17 1.66
Radius# 0.383 0.949 1.000 0.533 11.19 9.460 4.11 3.88
Satellites 0 0 1 2 about 53 about 53 about 27 13
* Distance from the sun in astronomical unit i.e. average mean distance of the earth is
149,598,000 km = 1 @ Density in gm/cm3
# Radius: Equatorial radius 6378.137 km = 1
Source: http://ptanetarynames.wr.usgs.gov/page/planets

7. Answer: (d)
Explanation:
Geological Time Scale
Eons Era Period Epoch Age/Years Life/Major Events
Before Present
Quaternary Holocene 0 - 10.000 Modern Man Homo
Pleistocene 10.000-2 Sapiens
million
Cainozoic Tertiary Pliocene 2-5 million Early Human
(From 65 Miocene 5-24 million Ancestor
million Oligocene 24-37 million Ape: Flowering
years to Eocene Plants and Trees
37-58 Million
the present Anthropoid Ape
Palaeocene 57-65 Million
times) Rabbits and Hare
Small Mammals:
Rats - Mice
Mesozoic Cretaceous 65-144 Million Extinction of
65-245 Jurassic 144-208 Million Dinosaurs Age of
Million Triassic 208-245 Million Dinosaurs Frogs
Mammals and turtles

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Palaeozoic Permian 245-286 Million Reptile dominate-
245-570 Carboniferous 286-360 Million replace amphibians
Million Devonian 360-408 Million First Reptiles:
Silurian 408-438 Million Vertebrates: Coal
beds Amphibians
Ordovician 438-505 Million
Cambrian 505-570 Million First trace of life on
land:
Plants
First Fish
No terrestrial Life :
Marine Invertebrate
Proterozoic Pre- 570-2.500 Soft-bodied
Archean Cambrian Million arthropods Blue
Hadean 570 Million 2.500-3.800 green Algae:
- 4.800 Million Unicellular bacteria
Million 3.800-4.800 Oceans and
Million Continents form -
Ocean and
Atmosphere are
rich in Carbon
dioxide
Origin of 5.000- 5,000 Million Origin of the sun
Stars 13.700 12,000 Million Origin of the
Supernova Million 13,700 Million universe
Big Bang

8. Answer: (b) of the Earth. These are solid bodies

Explanation: developed out of the materials same as, or
The analysis of the properties of the matter similar to, our planet. Hence, this becomes
indirectly provides information about the yet another source of information about the
interior. It is known through the mining interior of the Earth.
activity that the temperature and the The other indirect sources include
pressure increase with the increasing gravitation, magnetic field and seismic
distance from the surface towards the activity.
interior in deeper depths. The gravitation force (g) is not the same at
Moreover, it is also known that the density different latitudes on the surface. It is
of the material also increases with depth. It greater near the Poles and less at the
is possible to find the rate of change of Equator. This is because of the distance
these characteristics. Knowing the total
from the centre at the Equator being
thickness of the Earth, the scientists have
greater than that at the Poles. The gravity
estimated the values of temperature,
values also differ according to the mass of
pressure and the density of materials at
material. The uneven distribution of the
different depths.
mass of the material within the Earth
Another source of information is the
influences this value. The reading of the
meteors, which, at times, reach the Earth.
gravity at different places is influenced by
However, it may be noted that the material,
many other factors.
that becomes available for analysis from
These readings differ from the expected
the meteors, is not from the interior of the
values. Such a difference is called ‘gravity
Earth. The material and the structure
anomaly’.
observed in the meteors are similar to those

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Gravity anomalies give us information changes as they travel through the
about the distribution of the mass of the materials with different densities. The
material in the crust of the Earth. Magnetic denser the material, the higher is the
surveys also provide information about the velocity. Their direction also changes as
distribution of the magnetic materials in they reflect or refract when coming across
the crustal portion and thus, provide the materials with different densities.
information about the distribution of the The P-waves move faster and are the
materials in this part. Seismic activity is first to arrive at the surface. These are
one of the most important sources of also called the ‘primary waves’. The P-
information about the interior of the Earth. waves are similar to the sound waves. They
travel through gaseous, liquid and solid
9. Answer: (d) materials.
Explanation: The S-waves arrive at the surface with
The release of energy occurs during an some time lag. These are also called the
earthquake along a fault. A fault is a sharp ‘secondary waves’. An important fact
break in the crustal rocks. The rocks along about the S-waves is that they can travel
a fault tend to move in opposite directions. only through solid materials.
As the overlying rock strata press them, the
friction locks them together. 11. Answer: (c)
However, their tendency to move apart at Explanation:
some point of time overcomes the friction. Propagation of the Earthquake Waves:
As a result, the blocks get deformed and Different types of earthquake waves travel
eventually, they slide past one another in different manners. As they move or
abruptly. This causes a release of energy propagate, they cause vibrations in the
and the energy waves travel in all body of the rocks through which they pass.
directions. The point where the energy is The P-waves vibrate parallel to the
released is called the focus of an direction of the wave. This exerts
earthquake, alternatively, it is called the pressure on the material in the direction
hypocentre. The energy waves travelling in of propagation. As a result, it creates
different directions reach the surface. The density differences in the material
point on the surface, nearest to the leading to stretching and squeezing of
focus, is called the epicentre. It is the the material. Other three waves vibrate
first one to experience the waves. It is a perpendicular to the direction of
point directly above the focus. propagation. The direction of vibrations of
the S-waves is perpendicular to the wave
10. Answer: (b) direction in the vertical plane.
Explanation: Hence, they create troughs and crests in
Earthquake waves are basically of two the material through which they pass. The
types – body waves and surface waves. surface waves are considered to be the
Body waves are generated due to the most damaging waves.
release of energy at the focus and move in
all directions travelling through the body of 12. Answer: (a)
the Earth. Hence, the name body waves. Explanation:
The body waves interact with the surface Emergence of the Shadow Zone: The
rocks and generate a new set of waves, earthquake waves get recorded in the
called the surface waves. These waves move seismographs located at far off locations.
along the surface. The velocity of the waves However, there exist some specific areas

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where the waves are not reported. Such
a zone is called the ‘shadow zone’. The
study of different events reveals that for
each earthquake, there exists an altogether
different shadow zone.
The figures given below (a) and (b) show the
shadow zones of P and S-waves. It was
observed that the seismographs located at
any distance within 105° from the
epicentre, recorded the arrival of both P-
and S-waves.
However, the seismographs located beyond
145° from the epicentre record the arrival
of the P-waves, but not that of the S-waves.
Thus, a zone between 105° and 145° from
the epicentre was identified as the shadow
zone for both the types of waves. The entire 13. Answer: (b)
zone beyond 105° does not receive the S- Explanation:
waves. The shadow zone of the S-waves is
Mass movements transfer the mass of rock
much larger than that of the P-waves. The
debris down the slopes under the direct
shadow zone of the P-waves appears as a
influence of gravity. That means, air, water
band around the Earth between 105° and
or ice do not carry debris with them from
145° away from the epicentre. The shadow
place to place, but on the other hand, the
zone of the S-waves is not only larger in
debris may carry with it air, water or ice.
extent, but it is also a little over 40% of the
The movements of mass may range from
Earth’s surface.
slow to rapid, affecting shallow to deep
columns of materials and include creep,
flow, slide and fall. Gravity exerts its force
on all matters, both bedrock and the
products of weathering. So, weathering is
not a pre-requisite for mass movement,
though it aids mass movements.
Mass movements are very active over
weathered slopes, rather than over un-
weathered materials. Mass movements are
aided by gravity and no geomorphic agents,
like running water, glaciers, wind, waves
and currents participate in the process of
mass movements.
Several activating causes precede mass
movements. These are: (i) removal of
support from below to the materials above
through natural or artificial means; (ii)
increase in gradient and height of the
slopes; (iii) overloading through addition of
materials naturally or by artificial filling;
(iv) overloading due to heavy rainfall,

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saturation and lubrication of slope 15. Answer: (a)
materials; (v) removal of material or load Explanation:
from over the original slope surfaces; (vi) In humid regions, which receive heavy
occurrence of earthquakes, explosions or rainfall, running water is considered the
machinery; (vii) excessive natural seepage; most important of the geomorphic agents in
(viii) heavy drawdown of water from lakes, bringing about the degradation of the land
reservoirs and rivers, leading to slow surface. There are two components of
outflow of water from under the slopes or running water. One is overland flow on
river banks; and (ix) indiscriminate removal general land surface as a sheet. Another is
of natural vegetation. linear flow as streams and rivers in the
‘Heave’ (heaving up of soils due to frost valleys.
growth and other causes); ‘Flow’; and ‘Slide’ Most of the erosional landforms made by
are the three forms of movements. running water are associated with vigorous
and youthful rivers flowing over steep
gradients. There may be depositional forms
14. Answer: (d)
associated with the streams flowing over
Explanation: steep slopes.
Landslides are relatively rapid and In the early stages, down-cutting dominates
perceptible movements. The materials during which irregularities, such as
involved are relatively dry. The size and waterfalls and cascades, will be removed. In
shape of the detached mass depend on the the middle stages, streams cut their beds
nature of discontinuities in the rock, the slower and lateral erosion of valley sides
degree of weathering and the steepness of becomes severe.
the slope. Gradually, the valley sides are reduced to
Depending upon the type of movement of lower and lower slopes. The divides
the materials, several types are identified in between the drainage basins are likewise
this category. Slump is slipping of one or lowered until they are almost completely
several units of rock debris with a flattened, leaving finally, a lowland of faint
backward rotation with respect to the slope relief with some low resistant remnants,
over which the movement takes place. called the ‘monadnocks’, standing out here
and there. This type of plain, forming as
Rapid rolling or sliding of the Earth debris,
a result of stream erosion, is called a
without backward rotation of mass, is
‘peneplain’ (an almost plain).
known as debris slide. Debris fall is nearly
a free fall of the Earth debris from a vertical
16. Answer: (c)
or overhanging face. Sliding of individual
rock masses down bedding, joint or fault Explanation:
surfaces is rockslide. Valleys start as small and narrow rills; the
rills will gradually develop into long and
Over steep slopes, rock sliding is very fast
wide gullies; the gullies will further deepen,
and destructive. Slides occur as planar
widen and lengthen to give rise to the
failures along discontinuities, like bedding
valleys. Depending upon dimensions and
planes that dip steeply. Rock fall is free
shape, many types of valleys, like V-shaped
falling of rock blocks over any steep slope,
valley, gorge, canyon, etc., can be
keeping itself away from the slope. Rock
recognised. A gorge is a deep valley with
falls occur from the superficial layers of the
very steep to straight sides and a canyon is
rock face, an occurrence that distinguishes characterised by steep step-like side slopes
it from rockslide, which affects the and may be as deep as a gorge. A gorge is
materials upto a substantial depth. almost equal in width at its top, as well

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as its bottom. In contrast, a canyon is sized materials, like sand, silt and clay, are
wider at its top than at its bottom. In carried by relatively slow moving waters in
fact, a canyon is a variant of gorge. Valley gentler channels, usually found in the
types depend upon the type and structure plains and deposited over the bed and
of the rocks in which they form. For when the waters spill over the banks
example, canyons commonly form in during flooding above the bed. A river bed
horizontal bedded sedimentary rocks and made of river deposits is the active
gorges form in hard rocks. floodplain. The floodplain above the
bank is inactive floodplain. Inactive
17. Answer: (c) floodplain above the banks basically
contain two types of deposits — flood
Explanation:
deposits and channel deposits.
In streams that flow rapidly over steep
Natural levees and point bars are some of
gradients, normally erosion is concentrated
the important landforms found associated
on the bottom of the stream channel. Also,
with floodplains. Natural levees are found
in the case of steep gradient streams,
along the banks of large rivers. They are
lateral erosion on the sides of the valleys is
low, linear and parallel ridges of coarse
not much when compared to the streams
deposits along the banks of the rivers, quite
flowing on low and gentle slopes. Because
often cut into individual mounds. Point
of active lateral erosion, streams flowing
bars are also known as meander bars. They
over gentle slopes develop sinuous or
are found on the concave side of the
meandering courses. It is common to find
meanders of large rivers and are sediments
meandering courses over floodplains and
deposited in a linear fashion by flowing
delta-plains, where stream gradients are
waters along the bank. They are almost
very gentle. But, very deep and wide
uniform in profile and in width, and
meanders can also be found cut in hard
contain mixed sizes of sediments.
rocks. Such meanders are called ‘Incised’
or ‘Entrenched’ meanders.
River Terraces: River terraces are surfaces 19. Answer: (a)
marking old valley floor or floodplain levels. Explanation:
They may be bedrock surfaces without any In large flood and delta plains, rivers rarely
alluvial cover or alluvial terraces consisting flow in straight courses. Loop-like channel
of stream deposits. River terraces are patterns, called meanders, develop over
basically the products of erosion, as they flood and delta plains.
result due to vertical erosion by the stream Meander is not a landform, but is only a
into its own depositional flood-plain. There type of channel pattern. This is because of
can be a number of such terraces at (i) propensity of water flowing over very
different heights indicating former river bed gentle gradients to work laterally on the
levels. The river terraces may occur at the banks; (ii) unconsolidated nature of alluvial
same elevation on either side of the rivers deposits making up the banks with many
in which case they are called paired irregularities, which can be used by water
terraces. exerting pressure laterally; and (iii) Coriolis
force acting on the fluid water, deflecting it
18. Answer: (b) like it deflects the wind.
Explanation: When the gradient of the channel becomes
Floodplain is a major landform of river extremely low, water flows leisurely and
deposition. Large-sized materials are starts working laterally. Slight irregularities
deposited first when stream channel breaks along the banks slowly get transformed into
into a gentle slope. Thus, normally, fine- a small curvature in the banks; the

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curvature deepens due to deposition on the along parallel to sub-parallel joints. The
inside of the curve and erosion along the lapie field may eventually turn into
bank on the outside. If there is no somewhat smooth limestone pavements.
deposition and no erosion or undercutting,
the tendency to meander is reduced. 21. Answer: (a)
Normally, in the meanders of large Explanation:
rivers, there is active deposition along Stalactites hang as icicles of different
the concave bank and undercutting diameters. Normally they are broad at their
along the convex bank. The concave bank bases and taper towards the free ends,
is known as the ‘cut-off bank’, which shows showing up in a variety of forms.
up as a steep scarp and the convex bank Stalagmites rise up from the floor of the
presents a long, gentle profile. As meanders caves. In fact, stalagmites form due to
grow into deep loops, the same may get dripping water from the surface or
cut-off due to erosion at the inflection through the thin pipe of the stalactite
points and are left as ox-bow lakes. immediately below it. Stalagmites may
take the shape of a column, a disc, with
either a smooth, rounded bulging end or a
20. Answer: (d)
miniature crater like depression. The
Explanation:
stalagmite and stalactites eventually fuse to
Small to medium sized, round to sub- give rise to columns and pillars of different
rounded shallow depressions, called diameters.
swallow holes, form on the surface of
limestone through solution.
22. Answer: (b)
Sinkholes are very common in Explanation:
limestone/karst areas. A sinkhole is an
Cirques are the most common of
opening more or less circular at the top and
erosional landforms in glaciated
funnel-shapped towards the bottom, with mountains. The cirques quite often are
sizes varying in area from a few sq. m to a found at the heads of the glacial valleys.
hectare and with depth from a less than The accumulated ice cuts these cirques,
half a metre to thirty metres or more. while moving down the mountain tops.
The term doline is sometimes used to refer They are deep, long and wide troughs or
the collapse sinks. Solution sinks are more basins with very steep concave to vertically
common than collapse sinks. dropping high walls at its head, as well as
Quite often the surface runoff simply goes sides. A lake of water can be seen quite
down swallow and sink hole, and flows as often within the cirques after the glacier
underground streams and re-emerges at a disappears. Such lakes are called cirques
or tarn lakes. There can be two or more
distance downstream through a cave
cirques, one leading into another down
opening. When the sink holes and the
below in a stepped sequence.
dolines join together because of the
slumping of the materials along their Horns form through headward erosion of
the cirque walls. If three or more radiating
margins or due to roof collapse of caves,
glaciers cut headward until their cirques
long, narrow to wide trenches, called valley
meet, high, sharp pointed and steep sided
sinks or Uvalas, form.
peaks, called horns, form. The divides
Gradually, most of the surface of the between cirque side walls or head walls get
limestone is eaten away by these pits and narrow because of progressive erosion and
trenches, leaving it extremely irregular with turn into serrated or saw-toothed ridges,
a maze of points, grooves and ridges or sometimes referred to as arêtes, with very
lapies. Especially, these ridges or lapies sharp crest and a zig-zag outline.
form due to differential solution activity

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23. Answer: (b) A petrologist studies rocks in all their
Explanation: aspects, viz., mineral composition, texture,
Divergent Boundaries: Where new crust structure, origin, occurrence, alteration
is generated, as the plates pull away and relationship with other rocks.
from each other. The sites where the
plates move away from each other are 26. Answer: (b)
called the spreading sites. The best-known
Explanation:
example of divergent boundaries is the
When magma, in its upward movement,
Mid-Atlantic Ridge.
cools and turns into solid form, it is called
Convergent Boundaries: Where the crust
igneous rock. The process of cooling and
is destroyed, as one plate dived under
solidification can happen in the Earth’s
another. The location where the sinking of
crust or on the surface of the Earth.
a plate occurs is called a subduction zone.
There are three ways in which convergence Igneous rocks are classified based on
can occur. These are: (i) Between an texture. The texture depends upon size and
oceanic plate and a continental plate; (ii) arrangement of grains or other physical
Between two oceanic plates; and (iii) conditions of the materials. If molten
Between two continental plates. material is cooled slowly at great depths,
Transform Boundaries: Where the crust is mineral grains may be very large.
neither produced nor destroyed, as the Sudden cooling (at the surface) results in
plates slide horizontally past each other. small and smooth grains.
Transform faults are the planes of Intermediate conditions of cooling would
separation, generally perpendicular to the result in intermediate sizes of grains
mid-oceanic ridges.
making up igneous rocks. Granite, gabbro,
pegmatite, basalt, volcanic breccia and tuff
24. Answer: (c) are some of the examples of igneous rocks.
Explanation:
The Indian Plate includes the Peninsular 27. Answer: (b)
India and the Australian continental
Explanation:
portions. The subduction zone along the
Himalayas forms the northern plate Metamorphic rocks form under the action
boundary in the form of continent – of pressure, volume and temperature (PVT)
continent convergence. During the changes.
movement of the Indian Plate towards the Metamorphism is a process by which
Eurasian Plate, a major event that occurred already consolidated rocks undergo re-
was the outpouring of lava and the crystallisation and reorganisation of
formation of the Deccan Traps. materials within the original rocks.
India collided with Asia about 40-50 million Mechanical disruption and
years ago, causing rapid uplift of the reorganisation of the original minerals
Himalayas. within the rocks, due to breaking and
crushing without any appreciable
25. Answer: (c) chemical changes, is called dynamic
Explanation: metamorphism.
Petrology is the branch of geology that The materials of rocks chemically alter and
studies rocks and the conditions under re-crystallise due to thermal
which they form. metamorphism.
It is concerned with all three major types of In the process of metamorphism in some
rocks – igneous, metamorphic and rocks, grains or minerals get arranged in
sedimentary. layers or lines. Such an arrangement of

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minerals or grains in the metamorphic 30. Answer: (d)
rocks is called foliation or lineation. Explanation:
All processes that move, elevate or build up
28. Answer: (a) portions of the Earth’s crust come under
diastrophism. They include: (i) Orogenic
Explanation:
processes, involving mountain building
Depending upon the mode of formation, through severe folding, and affecting long
sedimentary rocks are classified into three and narrow belts of the Earth’s crust; (ii)
major groups: Epeirogenic processes, involving uplift or
(i) Mechanically formed: Sandstone, warping of large parts of the Earth’s crust;
conglomerate, limestone, shale, loess, (iii) Earthquakes, involving local relatively
etc. minor movements; and (iv) Plate tectonics,
involving horizontal movements of the
(ii) Organically formed: Geyserite, chalk,
crustal plates.
limestone, coal, etc.
(iii) Chemically formed: Chert, limestone,
31. Answer: (c)
halite, potash, etc.
Explanation:
Weathering processes are conditioned by
29. Answer: (c) many complex geological, climatic,
Explanation: topographic and vegetative factors. Climate
‘Rock Cycle’ is a continuous process, is of particular importance. Not only
through which old rocks are transformed weathering processes differ from climate to
into new ones. climate, but also the depth of the
weathering mantle.
Igneous rocks are primary rocks and
A group of weathering processes, viz.,
other rocks (sedimentary and
solution, carbonation, hydration, oxidation
metamorphic) form from these primary
and reduction act on the rocks to
rocks. Igneous rocks can be changed into decompose, dissolve or reduce them to a
metamorphic rocks. The fragments derived fine clastic state through chemical
out of igneous and metamorphic rocks form reactions by oxygen, surface and/or soil
into sedimentary rocks. water and other acids.
Sedimentary rocks themselves can turn
into fragments and the fragments can be a 32. Answer: (a)
source for the formation of sedimentary Explanation:
rocks. The crust is the outer-most solid part of the
Earth. It is brittle in nature. The thickness
of the crust varies under the oceanic and
the continental areas. The oceanic crust is
thinner as compared to the continental
crust. The mean thickness of the oceanic
crust is 5 km, whereas that of the
continental crust is around 30 km. The
continental crust is thicker in the areas
of major mountain systems. It is as
much as 70 km thick in the Himalayan
region.

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33. Answer: (b) low-explosivity. The upcoming lava
Explanation: moves in the form of a fountain and
 The portion of the interior beyond the throws out the cone at the top of the
crust is called the mantle. The mantle vent and develops into cinder cone.
extends from the Moho’s Discontinuity  Composite Volcanoes: These volcanoes
to a depth of 2,900 km. The upper are characterised by eruptions of cooler
portion of the mantle is called and more viscous lavas than basalt.
asthenosphere. The word ‘astheno’ These volcanoes often result in
means weak. It is considered to be explosive eruptions. Along with lava,
extending up to 400 km. large quantities of pyroclastic material
 It is the main source of magma that and ashes find their way to the ground.
finds its way to the surface during This material accumulates in the
volcanic eruptions. The crust and the vicinity of the vent openings, leading to
upper-most part of the mantle are the formation of layers, and this makes
called lithosphere. Its thickness ranges the mounts appear as composite
from 10-200 km. The lower mantle volcanoes.
extends beyond the asthenosphere. It is  Calderas: These are the most explosive
in solid state. of the Earth’s volcanoes. They are
usually so explosive that when they
erupt, they tend to collapse on
34. Answer: (c)
themselves, rather than building any
Explanation:
tall structure. The collapsed
The earthquake wave velocities helped in depressions are called ‘calderas’. Their
understanding the existence of the core of explosiveness indicates that the magma
the Earth. The Moho’s Discontinuity chamber supplying the lava is not only
forms the boundary between the crust huge, but is also in close vicinity.
and the mantle. The core mantle boundary
is located at the depth of 2,900 km. The
36. Answer: (b)
outer core is in liquid state, while the inner
core is in solid state. The core is made up Explanation:
of very heavy material, mostly  Dykes: When the lava makes its way
constituted by nickel and iron. It is through the cracks and the fissures
sometimes referred to as the ‘nife layer’. developed in the land, it solidifies
almost perpendicular to the ground.
35. Answer: (b) It gets cooled in the same position to
develop a wall-like structure. Such
Explanation:
structures are called dykes. These are
 Shield Volcanoes: Barring the basalt the most commonly found intrusive
flows, the shield volcanoes are the forms in the western Maharashtra area.
largest of all the volcanoes on the Earth. These are considered the feeders for the
The Hawaiian volcanoes are the most eruptions that led to the development of
famous examples. These volcanoes are the Deccan traps.
mostly made up of basalt, a type of
 Lapolith, Phacolith and Sills: As and
lava that is very fluid when erupted.
when the lava moves upwards, a
For this reason, these volcanoes are
portion of the same may tend to move in
not steep. They become explosive if
a horizontal direction, wherever it finds
somehow water gets into the vent;
a weak plain. It may get rested in
otherwise, they are characterised by
different forms. In case it develops into
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a saucer shape, concave to the sky domes. They appear on the surface only
body, it is called lapolith. A wavy mass after the denudational processes remove
of intrusive rocks, at times, is found at the overlying materials. They cover large
the base of synclines or at the top of areas and, at times, assume depth that
anticline in folded igneous country. may be several km. These are granitic
Such wavy materials have a definite bodies. Batholiths are the cooled
conduit to source beneath in the form of portion of the magma chambers.
magma chambers (subsequently
developed as batholiths). These are 38. Answer: (a)
called the phacoliths. The near
Explanation:
horizontal bodies of the intrusive
 If we observe the shape of the coastline
igneous rocks are called sills or sheets,
of the Atlantic Ocean, we will be
depending on the thickness of the
surprised by the symmetry of the
material. The thinner ones are called
coastlines on either side of the Ocean.
sheets, while the thick horizontal
No wonder, many scientists thought of
deposits are called sills.
this similarity and considered the
 Lacoliths: These are large dome-shaped
possibility of the two Americas, Europe
intrusive bodies with a level base and
and Africa, to be once joined together.
connected by a pipe-like conduit from
From the known records of the history
below. It resembles the surface volcanic
of science, it was Abraham Ortelius, a
domes of composite volcano. Only these
Dutch map maker, who first proposed
are located at deeper depths. It can be
such a possibility, as early as 1596.
regarded as the localised source of lava
Antonio Pellegrini drew a map showing
that finds its way to the surface. The
the three continents together.
Karnataka Plateau is spotted with the
 However, it was Alfred Wegener – a
Domal Hills of granite rocks. Most of
German meteorologist, who put forth a
these, now exfoliated, are the examples
comprehensive argument in the form of
of lacoliths or batholiths.
“the Continental Drift Theory” in 1912.
This was regarding the distribution of
37. Answer: (c) the oceans and the continents.
Explanation: According to Wegener, all the continents
 The lava that is released during volcanic formed a single continental mass and
eruptions, on cooling, develops into Mega Ocean surrounded the same.
igneous rocks. The cooling may take  The super continent was named
place either on reaching the surface or PANGAEA, which meant ‘All Earth’. The
also while the lava is still in the crustal mega-ocean was called PANTHALASSA,
portion. Depending on the location of meaning ‘All Water’. He argued that,
the cooling of the lava, igneous rocks around 200 million years ago, the super
are classified as volcanic rocks (cooling continent, Pangaea, began to split.
at the surface) and plutonic rocks Pangaea first broke into two large
(cooling in the crust). The lava that continental masses, as Laurasia and
cools within the crustal portions Gondwanaland, forming the northern
assumes different forms. These forms and the southern components,
are called intrusive forms. respectively. Subsequently, Laurasia
 Batholiths: A large body of magmatic and Gondwanaland continued to break
material that cools in the deeper depth into various smaller continents that
of the crust develops in the form of large exist today.

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39. Answer: (b)
Explanation:
 The study of the maps showing the distribution of seismic activity and volcanoes reveals a
line of dots in the central parts of the Atlantic Ocean, almost parallel to the coastlines. It
further extends into the Indian Ocean. It bifurcates a little south of the Indian sub-
continent, with one branch moving into East Africa and the other meeting a similar line from
Myanmar to New Guiana. This line of dots coincides with the mid-oceanic ridges. Another
area of concentration coincides with the Alpine-Himalayan system and the Rim of the Pacific
Ocean. In general, the foci of the earthquake in the areas of mid-oceanic ridges are at
shallow depths, whereas along the Alpine-Himalayan belt, as well as the Rim of the
Pacific, the earthquakes are deep-seated ones. The map of volcanoes also shows a similar
pattern. The Rim of the Pacific is also called the ‘Rim of Fire’, due to the existence of active
volcanoes in this area.

40. Answer: (b) common and they bring huge amounts

Explanation: of lava to the surface in this area.
The post-drift studies provided (ii) The rocks, equidistant on either sides
considerable information that was not of the crest of the mid-oceanic ridges,
available at the time Wegener put forth his show remarkable similarities in terms
concept of Continental Drift. Particularly, of period of formation, chemical
the mapping of the ocean floor and compositions and magnetic properties.
palaeomagnetic studies of the rocks from Rocks closer to the mid-oceanic
the oceanic regions revealed the following
ridges have normal polarity and are
facts:
the youngest. The age of the rocks
(i) It was realised that all along the mid-
increases as one moves away from the
oceanic ridges, volcanic eruptions are
crest.

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(iii) The ocean crust rocks are much Some important minor plates are listed
younger than the continental rocks. below:
The age of the rocks in the oceanic  Cocos plate: Between Central America
crust is nowhere more than 200 and Pacific plate.
million years old. Some of the  Nazca plate: Between South America
continental rock formations are as old and Pacific plate.
as 3,200 million years.  Arabian plate: Mostly the Saudi Arabian
(iv) The sediments on the ocean floor landmass.
are unexpectedly very thin. The  Philippine plate: Between the Asiatic
scientists were expecting, if the ocean and the Pacific plate.
floors were as old as the continent, to  Caroline plate: Between the Philippine
have a complete sequence of sediments and the Indian plate (North of New
for a period of much longer duration. Guinea).
However, nowhere was the sediment  Fuji plate: North-east of Australia.
column found to be older than 200
million years. 42. Answer: (b)
(v) The deep trenches have deep-seated Explanation:
earthquake occurrences, while in the Evidence in Support of the Continental
mid oceanic ridge areas, the quake foci Drift:
have shallow depths.
 The Matching of the Continents (Jig-
Saw-Fit): The shorelines of Africa and
41. Answer: (d) South America, facing each other,
Explanation: have a remarkable and unmistakable
match. It may be noted that a map
The Theory of Plate Tectonics proposes that
produced using a computer programme
the Earth’s lithosphere is divided into seven
to find the best fit of the Atlantic margin
major and some minor plates. Young fold
was presented by Bullard in 1964. It
mountain ridges, trenches, and/or faults
proved to be quite perfect. The match
surround these major plates.
was tried at 1,000-fathom line, instead
The major plates are as follows: of the present shoreline.
 Antarctica and the surrounding oceanic  Tillite: It is the sedimentary rock
plate. formed out of the deposits of the
 North American (with western Atlantic glaciers. The Gondwana system of
floor separated from the South sediments from India is known to have
American plate along the Caribbean its counterparts in six different
islands) plate. landmasses of the Southern
Hemisphere. At the base, the system
 South American (with western Atlantic
has thick tillite, indicating extensive
floor separated from the North
and prolonged glaciation. Counterparts
American plate along the Caribbean of this succession are found in Africa,
islands) plate. the Falkland Islands, Madagascar,
 Pacific plate. Antarctica and Australia. Overall
 India-Australia-New Zealand plate. resemblance of the Gondwana-type
sediments clearly demonstrates that
 Africa with the eastern Atlantic floor
these landmasses had remarkably
plate.
similar histories. The glacial tillite
 Eurasia and the adjacent oceanic plate. provides unambiguous evidence of

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paleoclimates and also of drifting of the Groundwater 9.5 0.68
continents.
Lakes 0.125 0.01
 Placer Deposits: The occurrence of the
Soil Moisture 0.065 0.005
rich placer deposits of gold in the
Ghana Coast and the absolute absence Atmosphere 0.013 0.001
of source rock in the region is an Streams and 0.0017 0.0001
amazing fact. The gold bearing veins are rivers
in Brazil and it is obvious that the gold
deposits of the Ghana are derived from
the Brazil Plateau, when the two 45. Answer: (a)
continents lay side by side. Explanation:
 Rocks of Same Age Across the Continental Shelf: The continental shelf is
Oceans: The radiometric dating the extended margin of each continent
methods, developed in the recent occupied by relatively shallow seas and
period, have facilitated correlating the gulfs. It is the shallowest part of the ocean
rock formation from different continents showing an average gradient of 1° or even
across the vast ocean. The belt of less. The shelf typically ends at a very steep
ancient rocks of 2,000 million years slope, called the shelf break.
from the Brazil Coast matches with The width of the continental shelves varies
those from western Africa. The earliest from one ocean to another. The average
marine deposits along the coastline of width of continental shelves is about 80
South America and Africa are of the
km. The shelves are almost absent or very
Jurassic Age. This suggests that the
narrow along some of the margins like the
ocean did not exist prior to that time.
coasts of Chile, the west coast of Sumatra,
etc. On the contrary, the Siberian shelf in
43. Answer: (c) the Arctic Ocean, the largest in the world,
Explanation: stretches to 1,500 km in width.
Exfoliation is a result, but not a process.
Flaking off of more or less curved sheets of
46. Answer: (a)
shells from over rocks or bedrocks results
Explanation:
in smooth and rounded surfaces.
Exfoliation can occur due to expansion and Continental slope: The continental slope
contraction induced by temperature connects the continental shelf and the
changes. Exfoliation domes and tors result ocean basins. It begins where the bottom of
due to unloading and thermal expansion, the continental shelf sharply drops off into
respectively. a steep slope. The gradient of the slope
region varies between 2-5°. The depth of
44. Answer: (b) the slope region varies between 200 and
3,000 m. The slope boundary indicates the
Explanation:
end of the continents. Canyons and
Water on the Earth’s surface
trenches are observed in this region.
Reservoir Volume Percentage Deep Sea Plain: Deep sea plains are gently
(Million of the total sloping areas of the ocean basins. These
Cubic km)
are the flattest and smoothest regions of
Oceans 1,370 97.25 the world. The depths vary between 3,000
Ice caps and 29 2.05 and 6,000m. These plains are covered with
Glaciers fine-grained sediments like clay and silt.

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47. Answer: (c) Atoll: These are low islands found in the
Explanation: tropical oceans consisting of coral reefs
Submarine Canyons: These are deep surrounding a central depression. It may
valleys, some comparable to the Grand be a part of the sea (lagoon), or sometimes
Canyon of the Colorado River. They are form enclosing a body of fresh, brackish, or
sometimes found cutting across the highly saline water.
continental shelves and slopes, often
extending from the mouths of large rivers. 50. Answer: (c)
The Hudson Canyon is the best known Explanation:
submarine canyon in the world. The temperature-depth profile for the ocean
Guyots: It is a flat topped seamount. They water shows how the temperature
show evidences of gradual subsidence decreases with the increasing depth. The
through stages to become flat topped profile shows a boundary region between
submerged mountains. It is estimated that the surface waters of the ocean and the
more than 10,000 seamounts and guyots deeper layers. The boundary usually begins
exist in the Pacific Ocean alone. around 100 - 400 m below the sea surface
and extends several hundred of metres
48. Answer: (d) downward.
Explanation: This boundary region, from where there is a
Ocean currents: Warm ocean currents rapid decrease of temperature, is called the
raise the temperature in cold areas while thermocline. About 90 per cent of the total
the cold currents decrease the temperature volume of water is found below the
in warm ocean areas. Gulf Stream (warm thermocline in the deep ocean. In this zone,
current) raises the temperature near the temperatures approach 0° C.
eastern coast of North America and the Factors affecting ocean salinity are
West Coast of Europe while the Labrador mentioned below:
Current (cold current) lowers the (i) The salinity of water in the surface layer
temperature near the north-east coast of of oceans depend mainly on evaporation
North America. and precipitation.
(ii) Surface salinity is greatly influenced in
49. Answer: (d) coastal regions by the fresh water flow
Explanation: from rivers, and in Polar Regions by the
processes of freezing and thawing of ice.
Mid-Oceanic Ridges: A mid-oceanic ridge
is composed of two chains of mountains (iii) Wind, also influences salinity of an area
separated by a large depression. by transferring water to other areas.
The mountain ranges can have peaks as (iv) The ocean currents contribute to the
high as 2,500 m and some even reach salinity variations. Salinity, temperature
above the ocean’s surface. Iceland is a part and density of water are interrelated.
of the mid- Atlantic Ridge. Hence, any change in the temperature
or density influences the salinity of
water in an area.

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