very nice video

1. Materials of the Earth’s crust
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2. Rocks are our world.
The planet Earth
is, essentially, just one big
interesting rock, sometimes
called "the third rock from the
sun."
The multi-faceted rock we live
on supports life in many ways.
The deep oceans, the vast
deserts, and the high
mountains, are just a few of
the ways rock emerges and
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supports life.

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4. What are rocks made up of ?
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5. Rocks and minerals
 A mineral is defined as a naturally occurring
inorganic substance, which has definite
physical properties and chemical composition.
Eg. Quartz (SiO2), Feldspar (K2O.Al2O3.6SiO2),
Mica (K4AlSi3O10(OH)2) etc are minerals.
 A rock is defined as an aggregate or mixture of
minerals.
Eg. Granite contains quartz, K-feldspar and K-
mica. Marble contains Calcite (CaCO3) and
Quartz.
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6. Common Rock-forming minerals
1. Quartz –
2. Feldspar –
3. Mica –
4. Calcite –
5. Clay –
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7. Quartz –
Most common mineral;
found in almost all rocks;
shades of white, gray, and pink,
mostly colourless with a glassy
lustre.
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8. Feldspar
Found in rocks like granite and basalt; colour may
vary as K is replaced by Ca or Na.
K-feldspar is pinkish or whitish while Ca and Na
feldspar is green or black
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9. Mica
white or colourless flakes in granite
and as black needles in basalt. K
may be replaced by Ca or Na.
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10. Calcite – Occurs in rocks like
limestone and marble. Colourless
or white; crystalline or amorphous.
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11. Clay
Similar to mica as it occurs as thin layers
differ as it has high water absorption
capacity;
found in rocks like shale, conglomerate etc.
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12. Absolute
Hardness Mineral
Hardness
1 Talc (Hydrated magnesium silicate) 1
2 Gypsum (Hydrated calcium sulfate) 2
3 Calcite (Calcium carbonate) 9
4 Fluorite (Used in toothpaste) 21
5 Apatite (Used in fertilizers) 48
6 Orthoclase 72
7 Quartz 100
8 Topaz 200
9 Corundum 400
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10 Diamond 1500

13. Types of rocks
Rocks are divided according to their origin
into igneous, sedimentary and metamorphic
rocks.
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14. Igneous Rocks
 Igneous Rock- rock that
has been formed by the
cooling and subsequent
solidification of a molten
mass of rock material,
known as magma.
 Depending upon the
conditions under which
the magma cooled, the
resulting rocks may be
coarse-grained or fine-
grained.
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15. Types of Igneous rocks
 Any molten rock material is known as magma as
long as it remains within the crust. If the magma
erupts out of a volcano and spreads out on the
surface of the earth, it is known as lava.
 Besides, magma contains dissolved gases
which are liberated once it comes out on the
earth’s surface.
 Based on the location where magma cools and
solidifies, the resultant igneous rocks can be
classified as follows.
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16. Intrusive Igneous rocks
 They are also called plutonic rocks.
 They are formed due to the cooling and
solidification of magma buried deep
within the earth (in the magma chamber).
A magma chamber that has cooled down
and solidified is called a pluton.
 Due to the lesser temperature difference
between the magma and surrounding
rocks, the magma cools down very
slowly.
 There is a lot of time for the mineral
crystals to grow in size. As a result, the
mineral crystals are large and visible and
the resultant rock is crystalline or coarse-
grained.
 Examples-Gabbro & Granite
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17. Extrusive igneous rocks
 They are also called volcanic
rocks.
 They are formed due to the
cooling and solidification of lava
on the earth’s surface under
atmospheric conditions.
 Due to the greater temperature
difference between the lava and
atmosphere, the lava cools down
very quickly.
 There is very little time for the
mineral crystals to grow in size. As
a result, the mineral crystals are
very small and the resultant rock
is glassy or fine-grained.
 Examples- Basalt & Rhyolite
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18. Hypabyssal igneous rocks
 They are formed due to the cooling
and solidification of magma within the
cracks and fissures of the surrounding
rock.
 The magma cools down at an
intermediate rate, therefore the mineral
crystals are
intermediate-sized and the resultant
rock is medium-grained.
 Structures formed due to the cooling
and solidification of magma within the
cracks and fissures of the surrounding
rock are known as igneous intrusions.
They may be of the following types.
 a) Dyke – A wall shaped igneous
intrusion, which cuts across the layers
of surrounding sedimentary rocks.
 b) Sill – A flat igneous intrusion that
lies between two layers of sedimentary
rock.
 c) Batholith – An irregularly shaped
igneous intrusion. The Geography Department 2011-12 18

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20. Sill Dike
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21. TYPES OF IGNEOUS ROCKS
Basaltic magma Granitic magma
Extrusive or
Basalt Rhyolite
Volcanic
Hypabyssal Dolerite Pegmatite
Intrusive or Plutonic Gabbro Granite
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22. INTRUSIVE V/S EXTRUSIVE IGNEOUS
ROCKS
 GRANITE • BASALT
 GABBRO •
•
 PEGMATITE • RHYOLITE
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23. Uses of igneous rocks
Granite and basalt are used extensively as
building stones since they are very strong
and durable.
Mica, which is used as an insulator and in
lubricants, is found in pegmatite.
Basalt is also used as a road metal.
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24. Sedimentary Rocks
Sedimentary rocks are so called because they are formed out of
sediment, which is the term given to broken rock fragments.
These rocks are
formed due to
deposition,
compaction and
cementation of the
broken rock
fragments weathered
by the agents of
gradation. The Geography Department 2011-12 24

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26. Process of Sedimentation of rocks
a) Deposition – Accumulation of sediment
in a low-lying area of the earth’s
surface, usually the continental shelf,
river basin or a lake. The sediments are
deposited in layers, also called stratified
(stratum meaning layer) rocks.
b) Compaction – On account of continuous
accumulation of sediments, the
underlying sediments are subject to
pressure due to which they tend to
occupy the least possible volume. This
process is called compaction.
c) Cementation – In this process, the rock fragments are bound together by
calcium carbonate, silica of iron oxide. Rainwater dissolves atmospheric gases
like carbon dioxide and results into a weak carbonic acid. This carbonic acid
takes the chemically weak minerals like mica, calcite and feldspar into
solution. This solution percolates through the sediment and occupies the
spaces between the rock fragments thereby cementing them. The processes of26
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compaction and cementation are often named collectively as lithification.

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28. Types of Sedimentary Rocks
 Mechanically formed Sedimentary rocks
 They are also called fragmental or clastic
rocks.
 Dynamic agents like rivers, glaciers, sea
waves and wind erode rocks.
 Sediments are transported and deposited in
low-lying areas of the earth where they
undergo the process of lithification.
 Examples of mechanically formed
sedimentary rocks include
 Sandstone – A rock made up of well-
rounded grains of quartz cemented together.
 Shale – A rock made up of very small flat
grains of clay and mica cemented together.
 Conglomerate. – A rockGeography Department 2011-12
The made up of large 28
pieces of other rocks cemented together

29. Types of Sedimentary Rocks
 Chemically formed sedimentary rocks
 They are also called non-clastic rocks.
 Some minerals or shells of microscopic
marine organisms are dissolved by water.
 Minerals precipitate directly from a
saturated solution followed by
evaporation of the water.
 Examples of chemically formed
sedimentary rocks include
 Limestone – A rock formed by the
compaction and cementation of shells in
shallow sea
 Gypsum - A rock formed by the
precipitation of calcium sulphate from sea
water
 Rock salt – A rock formed by the
compaction of sodium chloride under
pressure
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30. Types of Sedimentary Rocks
 Organically formed sedimentary rocks
 They are formed due to the decay of organisms and
their subsequent burial under sediments
 Examples of organically formed sedimentary rocks
include
 Coal – Formed due to the decay of dead plants under
fresh water conditions like those in a riverbed.
 Petroleum - Formed due to the decay of dead
animals under marine water conditions like those in a
continental shelf.
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31. Uses of sedimentary rocks
1. Rocks such as sandstone and limestone
are widely used as building stones.
2. Sedimentary rocks contain deposits of
important minerals like iron ore,
manganese, bauxite,
gypsum, coal and petroleum.
3. Fossils present in sedimentary rocks help
to determine the absolute and / or relative
age of rocks.
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32. Metamorphic Rocks
When other rocks are subjected to conditions of
heat and pressure, they convert to
metamorphic rocks.
As a result of metamorphism, rocks lose their
original physical structures (such as layering in
the case of sedimentary rocks) and their
chemical composition
is also altered
(new minerals are formed).
Rocks shown here- Micaschist,
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Quartzite & Marble

33. Agents of Metamorphism
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35. The sources of heat and pressure
involved in the formation of
metamorphic rocks are listed as
follows.
Heat – Magma, friction caused by the
rubbing of lithospheric plates against
each other
Pressure – Overlying sediments, rising
magma, collision of lithospheric plates
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36. Areas where metamorphic rocks are
found
1. Near igneous intrusions
2. Mountain belts
3. Deep in the earth’s crust
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37. Types of metamorphism
 Contact metamorphism
 Occurs due to alteration of
surrounding rocks by
magma, hence common
near igneous intrusions.
 Area of rocks affected is
very less, not beyond a few
hundred metres from the
magma.
 Heat is the dominant agent
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of metamorphism

38. Types of metamorphism
Regional metamorphism
Occurs due to movement of lithospheric
plates, hence common in mountain belts.
Area of rocks affected is very large, often
thousands of square kilometres.
Both heat and pressure play a
predominant role.
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39. Examples of metamorphic rocks
 Schist
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40. Examples of metamorphic rocks
Gneiss
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41. Examples of metamorphic rocks
Marble
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42. Examples of metamorphic rocks
 Basalt ------->Schist
 Granite ------->Gneiss (pronounced as ‘nice’)
 Shale ------->Slate
 Slate ------->Schist
 Sandstone ------->Quartzite
 Limestone ------->Marble
 Coal ------->Graphite
Take a Quiz
http://www.fi.edu/fellows/fellow1/oct98/expert/index.html
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http://www.kidsgeo.com/geology-games/rocks-game.php

43. The Rock Cycle
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Interactive rock cycle: http://www.learner.org/interactives/rockcycle/diagram.html

44. THE ROCK CYCLE
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45. Rock Cycle
 The classic rock cycle illustrates the relationship
between the three main types of rock found on the
Earth. In its simplest form, it demonstrates that
igneous rock, which is formed by the cooling of
magma, is in turn exposed to natural processes such
as weathering, erosion, and compaction, creating
sedimentary rock or exposed to heat and pressure,
creating metamorphic rocks. The application of heat
then turns sedimentary rock into metamorphic rock or
exposure to agents of gradation converts them back
into sediments, and further heating causes the
metamorphic rocks to melt and in process to turn full
circle, creating magma once more whereas further
pressure can convert them into another metamorphic
rock. However, the cycle does not necessarily have to
pass through all these stages.
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46. ORES AND GEMSTONES
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47. ORES
A mineral is said to be an ore if it contains
one or more elements, usually metals that
can be extracted from it in a profitable
manner
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48. ORES
Examples of minerals that are ores
Haematite (Fe2O3) – Ore of Iron
Chalcopyrite (CuFeS2) – Ore of Copper
Magnetite (Fe3O4) – Ore of Iron
Galena (PbS) – Ore of Lead
Bauxite (Al2O3) – Ore of Aluminium
Sphalerite (ZnS) – Ore of Zinc
Pyrolusite (MnO2) – Ore of Manganese
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49. GEMSTONES
Gemstones are minerals that are
treasured for their beauty and durability.
Their value generally depends on four
features:
The beauty of the stone itself
Its rarity
Its hardness and toughness
The skill with which it has been cut and
polished.
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50. GEMSTONES
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51. GEMSTONES
Month of birth Birthstone Colour
January Garnet Red
February Aquamarine Blue-green
March Amethyst Purple
April Diamond Colourless
May Emerald Green
Metallic white with a
June Pearl
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52. GEMSTONES
Month of birth Birthstone Colour
July Ruby Red
Honey yellow or
August Peridot
green
September Sapphire Blue
Metallic white with a
October Opal
play of colours
November Topaz Yellow
Blue-green to
December Turquoise
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greenish-grey 52

53. A quick Recap
 Answer the following questions by clicking on
the right choice.
 If your answer is right you will move on to the
next question by clicking on the arrow
 If your answer is not correct, you must go
back to the question by clicking on the arrow
Please do not skip any slide
Have a nice time and fun learning.
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54. Can wood be called a mineral?
Yes, it is naturally occurring
No, it does not have a chemical formula
Yes, it has a fixed chemical formula
No, its organic
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55. OOPS!
That’s the wrong answer. Try Again
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56. CORRECT!
Move on to the next question.
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57. Mineral is to compound as Rock is to
Element
Compound
Mixture
Solution
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58. OOPS!
That’s the wrong answer. Try Again
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59. CORRECT!
Move on to the next question.
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60. Which of the following is NOT a correct
point of difference between lava and
magma?
 Lava is found outside the earth while magma
is found inside the earth.
 Lava does not contain gases while magma
contains gases.
 Cooling of lava results in extrusive rocks
while cooling of magma results in intrusive
rocks.
 Lava is less viscous (flows faster) ; magma is
more viscous(moves slowly)
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61. OOPS!
That’s the wrong answer. Try Again
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62. CORRECT!
Move on to the next question.
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63. Which of the following is NOT a
characteristic of intrusive rocks?
They are dark in colour.
They form inside the earth.
They form due to slow cooling of magma.
They have large crystals.
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64. OOPS!
That’s the wrong answer. Try Again
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65. CORRECT!
Move on to the next question.
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66. Which of the following is a wall shaped
igneous intrusion cutting across layers of
sedimentary rocks?
Sill
Dyke
Batholith
Laccolith
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67. OOPS!
That’s the wrong answer. Try Again
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68. CORRECT!
Move on to the next question.
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69. Match the following
A Pegmatite 1 Basaltic equivalent of granite
B Gabbro 2 Hypabassal basaltic rock
C Rhyolite 3 Hyabassal granitic rock
D Dolerite 4 Extrusive rock of granitic composition
•A-2; B-1; C-4; D-3
•A-3; B-4; C-1; D-2
•A-3; B-1; C-4; D-2
•A-4; B-1; C-3; D-2
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70. OOPS!
That’s the wrong answer. Try Again
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71. CORRECT!
Move on to the next question.
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72. Which of the following is the black
coloured rock used as a kitchen platform?
Basalt
Limestone
Granite
Marble
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73. OOPS!
That’s the wrong answer. Try Again
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74. CORRECT!
Move on to the next question.
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75. Which of the following rocks is made up
of well-rounded grains of quartz
cemented together?
Shale
Conglomerate
Limestone
Sandstone
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76. OOPS!
That’s the wrong answer. Try Again
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77. CORRECT!
Move on to the next question.
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78. Which of the following rocks will form due
to the evaporation and compaction of a
super-saturated solution of calcium
sulphate?
Rock Salt
Gypsum
Limestone
Dolomite
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79. OOPS!
That’s the wrong answer. Try Again
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80. CORRECT!
Move on to the next question.
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81. Which process leads to the formation of
limestone?
Compaction and cementation of shells in
shallow parts of the continental shelf.
Dissolution of shells in the deep sea
followed by super saturation and
evaporation.
Dissolution of existing limestone by
rainwater followed by deposition in
underground caves and channels
All of the above.
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82. OOPS!
That’s the wrong answer. Try Again
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83. CORRECT!
Move on to the next question.
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84. Which of the following is NOT TRUE
about the formation of coal?
It forms in fresh water conditions.
It forms due to decay of dead plants.
It can also form due to decay of dead
animals.
It requires a protective environment for its
formation.
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85. OOPS!
That’s the wrong answer. Try Again
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86. CORRECT!
Move on to the next question.
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87. Which of the following is NOT TRUE
about the formation of petroleum?
It forms only in marine conditions.
Marine micro-organisms like
foraminifera are a must for its formation.
After its formation, it remains at the
same place.
It forms due to decay of dead bodies of
animals.
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88. OOPS!
That’s the wrong answer. Try Again
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89. CORRECT!
Move on to the next question.
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90. Which of the following mineral is not
found in sedimentary rocks?
Iron Ore
Mica
Bauxite
Gypsum
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91. OOPS!
That’s the wrong answer. Try Again
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92. CORRECT!
Move on to the next question.
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93. Which of the following is NOT TRUE
about metamorphism?
It involves a physical change in the
physical properties of a rock.
Minerals do not change.
Even metamorphic rocks can be
metamorphosed.
It may occur on account of heat or
pressure or both.
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94. OOPS!
That’s the wrong answer. Try Again
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95. CORRECT!
Move on to the next question.
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96. Where can you find metamorphic rocks?
Near Igneous intrusions.
Deep in the earth’s crust.
Fold mountain belts.
All of the above.
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97. OOPS!
That’s the wrong answer. Try Again
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98. CORRECT!
Move on to the next question.
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99. Which of the following is not a
metamorphic rock?
Basalt
Marble
Schist
Gneiss
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100. OOPS!
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101. CORRECT!
Move on to the next question.
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