Rocks: Types, Formation, and Importance in Geology
Dr.D.Y.patil College Of
Education(B.Ed),pimpri,Pune-18
Subject- Geography
Topic- Rocks
Asst.Prof. Ratnamala
Baviskar
Inspiration- Principal Dr.Rekha Pathak
•
A
rock
is
a solid cumulative of minerals
located
in
the earth's
lithosphere.
•
Rocks are generally
classified
into igneous, sedimentary
and
metamorphic rocks.
•
Rocks consist
of
mixtures
of minerals,
fragments
of
other
rocks and
organic
matter.
•
These
are
classified on
the
basis
of
their
mineral, chemical
and
textural
composition.
•
Rocks are essentially mixtures and
therefore
it is
not possible
to
determine detailed physical
and
chemical
properties.
Asst.Prof. Baviskar R.M.
•
Rocks are extremely important
in
terms
of
their properties
of
stability
and strength
as
a geological
material
on
which
construction foundations are
made
and
historically
as
building
material from which important and monumental
buildings
are
made.
•
Stone used
for
wall
, building,
and
bridge construction
over
history
until
•
recent
times
is
generally cut from
natural
rocks.
•
The
building
stones
are
normally
extracted
by surface
quarrying,
drilled
and
split using diamond
saws
or
iron
wedges, and then shaped and
polished according
to
their
requirements.
Asst.Prof. Baviskar R.M.
What
is
a
Rock?
•
Naturally-occurring mixtures
of
minerals
, glass or
organic
matter.
•
Rocks are a mixture of different minerals
formed by natural processes in the
lithosphere.
•
The properties of rocks depend on the
constituent minerals and their proportion.
•
Silica , aluminum, magnesium and iron are the
major rock-forming minerals.
What
is a
Rock?
•
Rocks are divided into
3
groups
based
on
how
they
were
formed:
•
IGNEOUS
•
SEDIMENTARY
•
METAMORPHIC
•
Rocks are
continually changed
by many
processes, such as weathering, erosion,
compaction, cementation, melting, and
cooling
•
Rocks can change to and from the three
types
Types of Rocks
•
“Ignis”
=
Latin for
“
fire
”
•
Formed from the
cooling of either
magma or lava
•
The
most
abundant
type
of
rock
•
Classified according
to
their
origin
and
composition
•
Igneous rocks are
created
when
molten
magma
cools
down
and
is
split
into
two
main
types.
•
These
are
mainly
plutonic and
volcanic
rocks.
•
The
upper 10
miles
of
the earth's
crust
comprises
almost
entirely
of
igneous
rocks.
Asst.Prof. Baviskar R.M.
•
Plutonic or intrusive
rocks
come
into being
when
magma
cools
and
crystallizes
gradually within
the earth's
crust.
•
Granite
is
a
typical plutonic rock. Volcanic
or extrusive
rocks
results from
magma
reaching
the
surface either as
lava
or
as fragmental
missiles.
•
Basalt
and
pumice
are examples
of volcanic /
extrusive
rocks.
There
are more
than
700
types
of
igneous
rocks.
•
The
two
important factors used
for
the
classification of
igneous rocks are
the
particle
size,
and
the
mineral
composition of
the
rock.
Asst.Prof. Baviskar R.M.
ORIGIN—
Where rocks are
formed
•
Below ground
=
from magma (intrusive
igneous
rock)
•
Usually have
LARGE
crystal grains (they
cooled
slowly
)
Some have large
&
small
crystals
•
Above ground
=
from lava (extrusive
igneous
rock)
•
Usually have
SMALL or NO
crystals (they
cooled too
quickly
)
•
Formed from
sediments
(rock
fragments,
mineral grains,
animal
&
plant
remains) that
are
pressed
or cemented together or
when sediments
precipitate
out
of
a
solution.
•
These
sediments
are moved
by
wind, water,
ice or
gravity.
•
Sedimentary
rocks represent
7%
of the Earth’s
crust, but they cover
70%
of the Earth’s
surface.
•
Sedimentary
rocks are
fossil
-carrying
rocks.
•
Sedimentary
rock formation
results from
the
sedimentation
of
material
in
the earth's
surface
and
within
collections of
water
.
•
They
are
extensive
in
their
spread
over
the earth's
crust,
covering
70%
to
80%
of
the
land
area
,
but
they
comprise only
about 5%
of
the earth's
total
crust.
The
study
of
sedimentary
rock provides much
information
as to
the
evolution of
life
on
earth
.
Asst.Prof. Baviskar R.M.
•
The heavy sediments
press down
on the
layers beneath
(compaction)
•
Dissolved
minerals
flow between the
particles and
cement
(glue) them
together
(cementation)
•
Rocks that have changed
due
to intense
temperature
and
pressure
•
“Meta” means
“
change
”
and morphosis
means “
form
” in
Greek
•
Igneous, sedimentary and other
metamorphic rocks can change to
become metamorphic
rocks
*Metamorphic rocks form
when
rocks undergo
metamorphosis/changes due
to heat
and
pressure.
*
Igneous
and
sedimentary rocks
mainly
undergo
this change
and
become metamorphic
rocks.
*
Gneiss, marble,
slate,
schist and quartzite are
some
of
the
different
types
of
metamorphic
rocks.
*The
major
types
of
metamorphism are contact
and
regional.
*The
former
takes
place
when
magma
is
injected
into
the
surrounding
solid
rocks while,
the
latter
is
primarily
associated
with
large
masses
of rock
spread
over a very
wide
area.
*
This regional metamorphosis
is
caused
mainly
by temperature
and
pressure.
What occurs in
the Earth
to
change these
rocks?
•
Pressure
from overlying rock
layers
•
High
heat
, but not enough to melt the
rock
•
Rocks may
be
flattened
or bent or atoms
may
be
exchanged to form new
minerals.
Properties of metamorphic
rocks
•
Usually resistant to
weathering and
erosion
and are therefore very
hard-
wearing.
•
Can be
polished to
give
a
smooth
shiny
surface.
•
Example
:
Marble,
slate.
Examples
of
rocks
becoming
metamorphic
•
Example
:
marble formed from
limestone
Where
do
metamorphic rocks
usually
form?
•
Where magma
intrudes
relatively
cool
rock
•
Near
colliding
plates (near
mountain
ranges)
•
Places
that are covered
miles thick
with other rock
causing pressure
•
When
hot
water
flows
between
rocks
Rocks are solid accumulations of minerals found in the Earth's lithosphere. They are classified into igneous, sedimentary, and metamorphic types based on their mineral composition. Rocks play a crucial role as geological materials for construction and historical buildings. Learn about the properties, formation, and significance of rocks in this insightful overview.
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Dr.D.Y.patil College Of Education(B.Ed),pimpri,Pune-18 Subject- Geography Topic- Rocks Asst.Prof. Ratnamala Baviskar Inspiration- Principal Dr.Rekha Pathak
A rock is a solid cumulative of minerals located in the earth's lithosphere. Rocks are generally classified into igneous, sedimentary and metamorphic rocks. Rocks consist of mixtures of minerals, fragments of other rocks and organic matter. These are classified on the basis of their mineral, chemical and textural composition. Rocks are essentially mixtures and therefore it is not possible to determine detailed physical and chemical properties. Asst.Prof. Baviskar R.M.
Rocks are extremely important in terms of their properties of stability and strength as a geological material on which construction foundations are made and historically as building material from which important and monumental buildings are made. Stone used for wall , building, and bridge construction over history until recent times is generally cut from natural rocks. The building stones are normally extracted by surface quarrying, drilled and split using diamond saws or iron wedges, and then shaped and polished according to their requirements. Asst.Prof. Baviskar R.M.
What is a Rock? Naturally-occurring mixtures minerals, glass or organic matter. of
Rocks are a mixture of different minerals formed by natural processes in the lithosphere. The properties of rocks depend on the constituent minerals and their proportion. Silica , aluminum, magnesium and iron are the major rock-forming minerals.
What What is a is a Rock? Rock? Rocks are divided into 3 groups based on were formed: how they IGNEOUS SEDIMENTARY METAMORPHIC
Rocks are continually changed by many processes, such as weathering, erosion, compaction, cementation, melting, and cooling Rocks can change to and from the three types
Types of Rocks Igneous, rocks. Sedimentary Rocks Metamorphic Rocks
Ignis = Latin for fire Formed from the cooling of either magma or lava The most abundant type of rock Classified according to their origin and composition
Igneous rocks are created when molten magma cools down and is split into two main types. These are mainly plutonic and volcanic rocks. The upper 10 miles of the earth's crust comprises almost entirely of igneous rocks. Asst.Prof. Baviskar R.M.
Plutonic or intrusive rocks come into being when magma cools and crystallizes gradually within the earth's crust. Granite is a typical plutonic rock. Volcanic or extrusive rocks results from magma reaching the surface either as lava or as fragmental missiles. Basalt and pumice are examples of volcanic / extrusive rocks. There are more than 700 types of igneous rocks. The two important factors used for the classification of igneous rocks are the particle size, and the mineral composition of the rock. Asst.Prof. Baviskar R.M.
ORIGIN Where rocks are formed Below ground = from magma (intrusive igneous rock) Usually have LARGE crystal grains (they cooled slowly)
Above ground = from lava (extrusive igneous rock) Usually have SMALL or NO crystals (they cooled too quickly)
Formed from sediments (rock fragments, mineral grains, animal & plant remains) that are pressed or cemented together or when sediments precipitate out of a solution.
These sediments are moved by wind, water, ice or gravity. Sedimentary rocks represent 7% of the Earth s crust, but they cover 70% of the Earth s surface. Sedimentary rocks are fossil-carrying rocks.
Sedimentary rock formation results from the sedimentation of material in the earth's surface and within collections of water . They are extensive in their spread over the earth's crust, covering 70% to 80% of the land area, but they comprise only about 5% of the earth's total crust. The study of sedimentary rock provides much information as to the evolution of life on earth. Asst.Prof. Baviskar R.M.
The heavy sediments press down on the layers beneath (compaction)
Dissolved minerals flow between the particles and cement (glue) them together (cementation)
Rocks that have changed due to intense temperature and pressure Meta means change and morphosis means form in Greek Igneous, sedimentary and other metamorphic rocks can change to become metamorphic rocks
*Metamorphic rocks form when rocks undergo metamorphosis/changes due to heat and pressure. * Igneous and sedimentary rocks mainly undergo this change and become metamorphic rocks. * Gneiss, marble, slate, schist and quartzite are some of the different types of metamorphic rocks.
*The major types of metamorphism are contact and regional. *The former takes place when magma is injected into the surrounding solid rocks while, the latter is primarily associated with large masses of rock spread over a very wide area. * This regional metamorphosis is caused mainly by temperature and pressure.
What occurs in the Earth to change these rocks? Pressure from overlying rock layers High heat, but not enough to melt the rock Rocks may be flattened or bent or atoms may be exchanged to form new minerals.
Properties of metamorphic rocks Usually resistant to weathering and erosion and are therefore very hard- wearing. Can be polished to give a smooth shiny surface. Example: Marble, slate.
Examples of rocks becoming metamorphic Example: marble formed from limestone
Where do metamorphic rocks usually form? Where magma intrudes relatively cool rock Near colliding plates (near mountain ranges) Places that are covered miles thick with other rock causing pressure When hot water flows between rocks
