Rocks_introductionandfirstmeetingof week.ppt

Chapter 4
Chapter 4
Rocks
Rocks

The Rock Cycle
The Rock Cycle
H.W. pg. 93 ques. 1-4
H.W. pg. 93 ques. 1-4
 A
A rock
rock is a mixture of
is a mixture of
minerals, rock
minerals, rock
fragments, volcanic
fragments, volcanic
glass, organic matter,
glass, organic matter,
and other natural
and other natural
materials.
materials.
 All rocks slowly change
All rocks slowly change
through time, and the
through time, and the
model that we use to
model that we use to
show this slow change
show this slow change
is called the
is called the rock cycle
rock cycle.
.

Discovery of the Rock Cycle
Discovery of the Rock Cycle
 James Hutton
James Hutton
recognized that rocks
recognized that rocks
undergo changes in
undergo changes in
1788.
1788.

Rock Cycle
Rock Cycle
 As you can see the
As you can see the
rock cycle shows 3
rock cycle shows 3
different types of rock:
different types of rock:
1)
1) Sedimentary
Sedimentary
2)
2) Metamorphic
Metamorphic
3)
3) Igneous
Igneous
Also you see that all 3
Also you see that all 3
types can be formed in
types can be formed in
a number of ways.
a number of ways.
This shows that any rock
This shows that any rock
can change into any of
can change into any of
the three major rock
the three major rock
types.
types.

Rock Cycle
Rock Cycle
 Within the rock cycle rocks can be weathered
Within the rock cycle rocks can be weathered
to small rock and mineral grains.
to small rock and mineral grains.
 These grains could then be carried away by
These grains could then be carried away by
wind, water, or ice.
wind, water, or ice.
 This is what we call
This is what we call erosion
erosion. This does not
. This does not
mean that the minerals and chemical elements
mean that the minerals and chemical elements
that make up rock are destroyed.
that make up rock are destroyed.
 The elements that make up rocks are not
The elements that make up rocks are not
destroyed they are just redistributed in other
destroyed they are just redistributed in other
forms.
forms.

Igneous Rock
Igneous Rock
Section 4-2 H.W. pg. 97 questions 1-4
Section 4-2 H.W. pg. 97 questions 1-4

Igneous rock
Igneous rock forms when magma cools and
forms when magma cools and
hardens.
hardens.

At certain within the Earth, the temperature
At certain within the Earth, the temperature
and pressure are just right for rocks to melt
and pressure are just right for rocks to melt
and form magma.
and form magma.
Magma can be located at depths of 150km below
Magma can be located at depths of 150km below
the Earths surface. The temperature of this
the Earths surface. The temperature of this
magma can range between 650- 1,200
magma can range between 650- 1,200o
o
C,
C,
depending on their chemical compositions and
depending on their chemical compositions and
pressures exerted on them.
pressures exerted on them.

Igneous Rock
Igneous Rock

The reason that these rocks melt is because of heat
The reason that these rocks melt is because of heat
that is formed in the Earth’s interior.
that is formed in the Earth’s interior.

The heat comes from the decay of radioactive material
The heat comes from the decay of radioactive material
inside the Earth.
inside the Earth.

Another source of this heat is actually heat that is left
Another source of this heat is actually heat that is left
over from the formation of the planet, which was
over from the formation of the planet, which was
originally molten.
originally molten.

Since magma is less dense than the surrounding rocks
Since magma is less dense than the surrounding rocks
it is forced upward toward the surface, like in a
it is forced upward toward the surface, like in a
volcano.
volcano.

When magma reaches the Earths surface and flows
When magma reaches the Earths surface and flows
from volcanoes it is then called
from volcanoes it is then called lava
lava

Igneous Rock
Igneous Rock
So
So magma
magma is melted rock material composed of
is melted rock material composed of
common elements and fluids.
common elements and fluids.
As magma cools atoms and compounds rearrange
As magma cools atoms and compounds rearrange
themselves into new crystals called
themselves into new crystals called mineral grains
mineral grains.
.
And rocks form as these mineral grains grow
And rocks form as these mineral grains grow
together.
together.
So rocks that form from magma below the Earths
So rocks that form from magma below the Earths
surface are called intrusive.
surface are called intrusive.
These intrusive rocks stay underground until the land
These intrusive rocks stay underground until the land
above them are removed, either by erosion of by
above them are removed, either by erosion of by
physical means, and exposed to the surface.
physical means, and exposed to the surface.

Igneous Rock
Igneous Rock

Intrusive rocks
Intrusive rocks form
form
at deep depths of the
at deep depths of the
Earth. This causes the
Earth. This causes the
rocks to cool very
rocks to cool very
slowly.
slowly.
 Slowly cooled magma
Slowly cooled magma
will then produce very
will then produce very
large mineral grains that
large mineral grains that
we can see, within the
we can see, within the
intrusive rocks.
intrusive rocks.

Igneous Rock
Igneous Rock
 Extrusive igneous
Extrusive igneous rocks
rocks
are formed by the cooling of
are formed by the cooling of
lava on the surface of the
lava on the surface of the
Earth.
Earth.
 When lava cools on the
When lava cools on the
surface it could be exposed
surface it could be exposed
to water and air. This
to water and air. This
causes the lava to cool
causes the lava to cool
quickly and does not allow
quickly and does not allow
large mineral grains to form.
large mineral grains to form.
 Therefore extrusive igneous
Therefore extrusive igneous
rock looks fine grained.
rock looks fine grained.

Classifying Igneous Rock
Classifying Igneous Rock

Besides intrusive and extrusively forming. The
Besides intrusive and extrusively forming. The
type of igneous rock also depends on the
type of igneous rock also depends on the
magma from which it forms.
magma from which it forms.

An igneous rock can form from basaltic,
An igneous rock can form from basaltic,
andesitic, or granitic, magma.
andesitic, or granitic, magma.

The type of magma that rocks form from
The type of magma that rocks form from
determines important chemical and physical
determines important chemical and physical
properties of that rock.
properties of that rock.

These include mineral composition, density,
These include mineral composition, density,
color, and melting point.
color, and melting point.

Basaltic Rock
Basaltic Rock

These are dense dark colored igneous rock that
These are dense dark colored igneous rock that
form from magma that is rich in magnesium
form from magma that is rich in magnesium
and iron, and lack in silica.
and iron, and lack in silica.

The iron and magnesium give these rocks the
The iron and magnesium give these rocks the
dark color.
dark color.

This basaltic magma flows, largely from the
This basaltic magma flows, largely from the
mountains in Hawaii, which explains the black
mountains in Hawaii, which explains the black
color of Hawaii’s beaches.
color of Hawaii’s beaches.

Granitic Rock
Granitic Rock

These are light colored igneous rock that have
These are light colored igneous rock that have
a lower density than basaltic rocks.
a lower density than basaltic rocks.

Granitic magma has more silica and less iron
Granitic magma has more silica and less iron
and magnesium then basaltic magma
and magnesium then basaltic magma

Andesitic Rock
Andesitic Rock
 This type of magma has a
This type of magma has a
chemical composition that
chemical composition that
is between basaltic and
is between basaltic and
granitic rock, when dealing
granitic rock, when dealing
with silica, magnesium and
with silica, magnesium and
iron.
iron.
 It has more iron and
It has more iron and
magnesium than granitic
magnesium than granitic
and less silica than granitic.
and less silica than granitic.
 Usually found in volcanoes
Usually found in volcanoes
along the Pacific Coast.
along the Pacific Coast.

Metamorphic Rock
Metamorphic Rock
Section 4-3 H.W. pg 102 ques. 1-4
Section 4-3 H.W. pg 102 ques. 1-4
 Rocks that have changed because of changes in
Rocks that have changed because of changes in
temperature and pressure or the presence of hot,
temperature and pressure or the presence of hot,
watery fluids are called
watery fluids are called Metamorphic Rock.
Metamorphic Rock.
 These changes can be in the form of the rock or in its
These changes can be in the form of the rock or in its
composition or both.
composition or both.
 Metamorphic rocks can form from igneous,
Metamorphic rocks can form from igneous,
sedimentary or from other metamorphic rocks.
sedimentary or from other metamorphic rocks.
 Ex: When you add heat and pressure to granite, the
Ex: When you add heat and pressure to granite, the
mineral grains are flattened and a metamorphic rock
mineral grains are flattened and a metamorphic rock
called gneiss is formed.
called gneiss is formed.

Granite & Gneiss
Granite & Gneiss

How heat and Pressure effect rocks.
 Rocks beneath the Earth’s surface are under great
Rocks beneath the Earth’s surface are under great
pressure from the rock layers above them. Also,
pressure from the rock layers above them. Also,
temperature increases as the depth of the Earth
temperature increases as the depth of the Earth
increases.
increases.
 In some areas under the Earth’s surface the Temp and
In some areas under the Earth’s surface the Temp and
pressure is just right to allow rock to melt and magma
pressure is just right to allow rock to melt and magma
to form.
to form.
 In other areas, melting doesn’t occur but some
In other areas, melting doesn’t occur but some
mineral grains change by dissolving and
mineral grains change by dissolving and
recrystallizing, in the presence of liquids.
recrystallizing, in the presence of liquids.

 Depending on the amount of pressure and
Depending on the amount of pressure and
temperature applied, one type of rock can
temperature applied, one type of rock can
change into several different metamorphic
change into several different metamorphic
rocks, and every metamorphic rock can come
rocks, and every metamorphic rock can come
from several different parent rocks.
from several different parent rocks.
 Ex: The sedamentary rock shale will change
Ex: The sedamentary rock shale will change
into slate.
into slate.
 As you increase pressure slate turns into
As you increase pressure slate turns into
phyllite, then schist and then eventually gneiss.
phyllite, then schist and then eventually gneiss.


Lastly, schist can also form basalt.
Lastly, schist can also form basalt.

How Hot Fluids Effect Rocks
How Hot Fluids Effect Rocks
 Some fluids can move through rock. These
Some fluids can move through rock. These
fluids are usually hot and mostly water with
fluids are usually hot and mostly water with
dissolved elements, CO
dissolved elements, CO2
2 and compounds.
and compounds.
 When these fluids pass through rocks they
When these fluids pass through rocks they
react chemically with the rock to change its
react chemically with the rock to change its
composition.
composition.
 This occurs a lot when rock surrounds a hot
This occurs a lot when rock surrounds a hot
magma body and the fluids from the magma
magma body and the fluids from the magma
react with the surrounding rock.
react with the surrounding rock.

How to Classify Metamorphic Rock
How to Classify Metamorphic Rock
 Metamorphic rocks
Metamorphic rocks can form from igneous,
can form from igneous,
sedimentary, or other metamorphic rocks
sedimentary, or other metamorphic rocks
through their interaction with heat pressure
through their interaction with heat pressure
and hot fluids.
and hot fluids.
 We classify these rocks by their
We classify these rocks by their composition
composition
and texture.
and texture.

First is
First is Foliated
Foliated rocks
rocks. A metamorphic rock
. A metamorphic rock
is said to have foliated texture when mineral
is said to have foliated texture when mineral
grains in the rock line up in parallel layers.
grains in the rock line up in parallel layers.

Metamorphic foliated rock
 Two examples of
Two examples of
foliated rocks are slate
foliated rocks are slate
and gneiss.
and gneiss.

 Slate forms from a Sedimentary rock called
Slate forms from a Sedimentary rock called
shale.
shale.
 The minerals in shale arrange into layers when
The minerals in shale arrange into layers when
they are exposed to heat and pressure. This
they are exposed to heat and pressure. This
allows slate to separate easily along these
allows slate to separate easily along these
foliation layers.
foliation layers.
 The pressure is so great during this change that
The pressure is so great during this change that
the minerals in slate get pressed so tightly that
the minerals in slate get pressed so tightly that
water cannot pass through it, making it
water cannot pass through it, making it
virtually water tight.
virtually water tight.
 This unique property makes slate the optimal
This unique property makes slate the optimal
rock for the use of patios and paving around
rock for the use of patios and paving around
pools.
pools.

 Gneiss, another foliated
Gneiss, another foliated
rock, forms when granite is
rock, forms when granite is
changed. The foliation in
changed. The foliation in
gneiss shows up as
gneiss shows up as
alternating light and dark
alternating light and dark
bands.
bands.
 This is because during the
This is because during the
transformation from granite
transformation from granite
to gneiss the light atoms of
to gneiss the light atoms of
quartz and feldspar are
quartz and feldspar are
separated from the darker
separated from the darker
atoms of mica.
atoms of mica.

Non Foliated metamorphic Rock
 In
In non foliated metamorphic rock
non foliated metamorphic rock layering does not
layering does not
occur. The mineral grains grow and rearrange but do
occur. The mineral grains grow and rearrange but do
not form layers.
not form layers.
 This produces a non foliated texture.
This produces a non foliated texture.
 An example is when sandstone, a sedimentary rock
An example is when sandstone, a sedimentary rock
composed of mostly quartz grains, is exposed to heat
composed of mostly quartz grains, is exposed to heat
and pressure.
and pressure.
 The quartz grains here grow in size and become
The quartz grains here grow in size and become
interlocking like a jigsaw puzzle.
interlocking like a jigsaw puzzle.
 The resulting rock is called quartzite.
The resulting rock is called quartzite.

 Another example of non foliated metamorphic rock is
Another example of non foliated metamorphic rock is
marble.
marble.

Marble forms from the sedimentary rock limestone,
Marble forms from the sedimentary rock limestone,
which is rich with the mineral calcite.
which is rich with the mineral calcite.

Marble that is a different color than white is due to
Marble that is a different color than white is due to
the presence of other minerals besides calcite that is
the presence of other minerals besides calcite that is
present.
present.

Hornblende gives marble a black or greenish color
Hornblende gives marble a black or greenish color
 And hematite gives marble a reddish color.
And hematite gives marble a reddish color.

Sedimentary Rock
Sedimentary Rock
Section 4-4 H.W. Pg 109 ques. 1-5
Section 4-4 H.W. Pg 109 ques. 1-5

Igneous rocks are the most common rocks on Earth.
Igneous rocks are the most common rocks on Earth.
However we don’t see them a lot because they are
However we don’t see them a lot because they are
mostly beneath the Earths surface.
mostly beneath the Earths surface.

75% of the rocks that are exposed at the surface are
75% of the rocks that are exposed at the surface are
sedimentary rocks
sedimentary rocks.
.

Sediments are loose materials such as rock fragments,
Sediments are loose materials such as rock fragments,
mineral grains, and bits and pieces of shell that have
mineral grains, and bits and pieces of shell that have
been moved by wind, water, or ice
been moved by wind, water, or ice

These sediments come from already existing rock that
These sediments come from already existing rock that
were weathered or eroded.
were weathered or eroded.

Sedimentary rock forms when these sediments are
Sedimentary rock forms when these sediments are
pressed together by great pressure, or when minerals
pressed together by great pressure, or when minerals
form in solution.
form in solution.

Stacked Rocks
Stacked Rocks

Sedimentary rocks often form in layers. The
Sedimentary rocks often form in layers. The
older layers are on the bottom layers because
older layers are on the bottom layers because
they were deposited first.
they were deposited first.

Sometimes these layers can be disturbed by
Sometimes these layers can be disturbed by
the forces of nature. This will sometimes
the forces of nature. This will sometimes
overturn the layered sedimentary rock and the
overturn the layered sedimentary rock and the
oldest will no longer be on the bottom.
oldest will no longer be on the bottom.

Classifying Sedimentary Rocks
Classifying Sedimentary Rocks
 The sediments that form sedimentary rocks
The sediments that form sedimentary rocks
can be almost anything that is found in nature.
can be almost anything that is found in nature.
 Sediments can come from weathered or eroded
Sediments can come from weathered or eroded
igneous, metamorphic, sedimentary rocks.
igneous, metamorphic, sedimentary rocks.
 And the composition of sedimentary rocks
And the composition of sedimentary rocks
depends on the composition of the sediments
depends on the composition of the sediments
that formed that rock.
that formed that rock.
 Like the other rocks we spoke of, sedimentary
Like the other rocks we spoke of, sedimentary
rocks are classified by their composition and
rocks are classified by their composition and
are classified as:
are classified as: detrital, chemical, or
detrital, chemical, or
organic.
organic.

Detrital Sedimentary Rock

Detrital
Detrital means “to wear away” in Latin, and are
means “to wear away” in Latin, and are
made from broken fragments of other rocks.
made from broken fragments of other rocks.
 These broken fragments are compacted together by
These broken fragments are compacted together by
pressure and cemented together to form solid rock.
pressure and cemented together to form solid rock.

These broken fragments of rocks can form in a
These broken fragments of rocks can form in a
number of ways. One way is by weathering and
number of ways. One way is by weathering and
erosion.
erosion.

When rock is exposed to air, water, or ice it is
When rock is exposed to air, water, or ice it is
unstable and breaks down chemically and
unstable and breaks down chemically and
mechanically.
mechanically.

This process, which breaks down rocks into smaller
This process, which breaks down rocks into smaller
pieces, is called
pieces, is called weathering
weathering and the actual movement
and the actual movement
of these smaller pieces is called
of these smaller pieces is called erosion
erosion.
.

H.W. pg 114 questions 1-10
 Compaction is also a part of sedimentary rock
Compaction is also a part of sedimentary rock
formation.
formation.

Erosion moves sediments to a new location,
Erosion moves sediments to a new location,
where they will be deposited. Now layer upon
where they will be deposited. Now layer upon
layer of sediment builds up.
layer of sediment builds up.
 Pressure from all of the built up layers pushes
Pressure from all of the built up layers pushes
down on the lower layers causing the small
down on the lower layers causing the small
fragments to form solid rock. This process is
fragments to form solid rock. This process is
called
called compaction.
compaction.

 If the fragments are large, like the size of pebbles or
If the fragments are large, like the size of pebbles or
sand, pressure alone can’t make the solid rock form.
sand, pressure alone can’t make the solid rock form.
 When water moves through soil and rock, it picks up
When water moves through soil and rock, it picks up
materials released from minerals during weathering.
materials released from minerals during weathering.
 This dissolved mineral solution then moves between
This dissolved mineral solution then moves between
the large loose rock sediments and cements them
the large loose rock sediments and cements them
together.
together.
 Cementation
Cementation, usually occurs when minerals such as
, usually occurs when minerals such as
quartz, calcite, and hematite are deposited between
quartz, calcite, and hematite are deposited between
sediments.
sediments.
 These minerals act as natural cement and hold
These minerals act as natural cement and hold
sediments together like glue, and forming detrital
sediments together like glue, and forming detrital
sedimentary rock.
sedimentary rock.

 Detrital rocks
Detrital rocks have a granular texture, kind of like
have a granular texture, kind of like
granulated sugar. And they are named according to
granulated sugar. And they are named according to
the shapes and sizes of the sediments that form them.
the shapes and sizes of the sediments that form them.
 Ex: The Sedimentary rocks, conglomerate and breccia
Ex: The Sedimentary rocks, conglomerate and breccia
both form from large sediments.
both form from large sediments.
 If the sediments are rounded, the rock is called
If the sediments are rounded, the rock is called
conglomerate. If the sediments are sharp then the
conglomerate. If the sediments are sharp then the
rock is called breccia.
rock is called breccia.
 The roundness of sediment particles depends on how
The roundness of sediment particles depends on how
far they have been moved by wind or water.
far they have been moved by wind or water.

Materials Found in Sedimentary
Materials Found in Sedimentary
Rocks
Rocks
H.W. pg 114 ques. 11-20
H.W. pg 114 ques. 11-20
 The gravel sized sediments in conglomerate and
The gravel sized sediments in conglomerate and
breccia are often composed of quartz and feldspar.
breccia are often composed of quartz and feldspar.
 These 2 minerals (quartz, feldspar) can be found in
These 2 minerals (quartz, feldspar) can be found in
gneiss, granite, and limestone.
gneiss, granite, and limestone.
 The natural cement that holds the sediments in
The natural cement that holds the sediments in
sedimentary rock together are usually quartz and
sedimentary rock together are usually quartz and
calcite.
calcite.
 Sandstone if formed from smaller particles than
Sandstone if formed from smaller particles than
conglomerate and breccia, but they are made from
conglomerate and breccia, but they are made from
types of quartz and feldspar that are more resistant to
types of quartz and feldspar that are more resistant to
weathering.
weathering.

Chemical Sedimentary Rock
 This is the second type of
This is the second type of
sedimentary rock, and it is
sedimentary rock, and it is
formed when dissolved
formed when dissolved
minerals come out of
minerals come out of
solution.
solution.
 Like our saltwater example,
Like our saltwater example,
mineral deposits can form
mineral deposits can form
sediments and rocks when
sediments and rocks when
sea or lake water
sea or lake water
evaporates.
evaporates.
 An example of chemical
An example of chemical
sedimentary rock is
sedimentary rock is
gypsum.
gypsum.
 Chemical sedimentary
Chemical sedimentary
rocks do not form from
rocks do not form from
pieces of preexisting rocks.
pieces of preexisting rocks.


Limestone- this is composed
Limestone- this is composed
mostly of Calcium Carbonate
mostly of Calcium Carbonate
CaCO
CaCO3
3. And forms when
. And forms when
calcium carbonate comes out of
calcium carbonate comes out of
solution as calcite and its many
solution as calcite and its many
crystals grow together to form
crystals grow together to form
limestone.
limestone.

Limestone is 50% calcite and is
Limestone is 50% calcite and is
usually deposited on the bottom
usually deposited on the bottom
of lakes or shallow seas.
of lakes or shallow seas.

A lot of the United States
A lot of the United States
bedrock is made of limestone.
bedrock is made of limestone.
And that is due to the fact that
And that is due to the fact that
seas covered much of the
seas covered much of the
country for millions of years.
country for millions of years.

 Rock Salt- When water is
Rock Salt- When water is
very rich in dissolved salt ,
very rich in dissolved salt ,
it often deposits the mineral
it often deposits the mineral
halite.
halite.
 Halite deposits can range in
Halite deposits can range in
thickness from a few meters
thickness from a few meters
to more than 400m.
to more than 400m.
 Companies mine these
Companies mine these
deposits because it is used
deposits because it is used
as a very important
as a very important
resource.
resource.
 Its used in the making of
Its used in the making of
glass, paper, soap, and some
glass, paper, soap, and some
dairy products. Also, its
dairy products. Also, its
processed and used as table
processed and used as table
salt.
salt.

Organic Sedimentary Rock
Organic Sedimentary Rock
 Rocks that are made of the remains of once-
Rocks that are made of the remains of once-
living things are called
living things are called organic sedimentary
organic sedimentary
rocks.
rocks.
 The most common of this type of this rock
The most common of this type of this rock
would be fossil rich limestone.
would be fossil rich limestone.
 The difference between regular limestone and
The difference between regular limestone and
fossil rich limestone is that fossil rich
fossil rich limestone is that fossil rich
limestone contains some remnant of once
limestone contains some remnant of once
living ocean organisms, instead of just calcite.
living ocean organisms, instead of just calcite.
 Ex: muscles, clams, coral, snails. They have
Ex: muscles, clams, coral, snails. They have
shells made from calcium carbonate. When
shells made from calcium carbonate. When
these shells cement together they form fossil
these shells cement together they form fossil
rich limestone.
rich limestone.

Fossil rich limestone
Fossil rich limestone
 If a rock is completely
If a rock is completely
made of shell fragments
made of shell fragments
that you can see, the
that you can see, the
rock is called coquina.
rock is called coquina.

Organic sedimentary rock
Organic sedimentary rock

Chalk- is another organic sedimentary rock
Chalk- is another organic sedimentary rock
that is made of microscopic shells.
that is made of microscopic shells.
 When you write with naturally occurring chalk
When you write with naturally occurring chalk
you a crushing and smearing the calcite-shells
you a crushing and smearing the calcite-shells
remains of a once living organism.
remains of a once living organism.

Coal- is another useful organic sedimentary
Coal- is another useful organic sedimentary
rock. It forms when dead plants are buried
rock. It forms when dead plants are buried
under other sediments in swamps.
under other sediments in swamps.

Microorganisms feed off of and change these
Microorganisms feed off of and change these
plant materials, and they are compacted over
plant materials, and they are compacted over
millions of years to eventually form coal.
millions of years to eventually form coal.

Test on chapter 3 in one
Test on chapter 3 in one
week!!!!!!!!!!!!!
week!!!!!!!!!!!!!

Rocks_introductionandfirstmeetingof week.ppt

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Rocks_introductionandfirstmeetingof week.ppt