Transcript IGNEOUS ROCKS

IGNEOUS ROCKS
Pg 99 text book
http://my.hrw.com
What you will learn
• Describe three ways that igneous rock forms.
• Explain how the cooling rate of magma affects
the texture of igneous rock.
• Distinguish between igneous rock that cools
within Earth’s crust and igneous rock that
cools at Earth’s surface.
http://www.webquest.hawaii.edu/kahihi/sciencedictionary/images/magma_flow_up.gif
What is
the
origin of
Igneous
Rock?
Igneous rock
begins as magma
What are
the ways
that
magma
can
form?
There are three ways
magma can form:
1. when rock is
heated,
2. when pressure is
released,
3. when rock
changes
composition.
Put a drawing like this on pg 37 in your
nb
What
happens
to
magma
when it
cools at
different
rates?
The longer it takes for the
magma or lava to cool,
the more time mineral
crystals have to grow.
The more time the
crystals have to grow, the
larger the crystals.
The larger the crystals are
the coarser the texture of
the resulting igneous rock
is.
What
happens
to
magma
when it
cools at
different
rates?
The less time magma takes
to cool,
the less time crystals have
to grow.
Therefore, the rock that is
formed will be fine grained.
What
happens
to
magma
when it
cools at
different
rates?
Fine-grained igneous
rock contains very
small crystals, or if
the cooling is very
rapid, it contains no
crystals.
What are the
Compositions
and Textures
of Igneous
Rock?
What are
examples of
each type?
What is
Intrusive
Igneous
Rock?
Magma that
cools and
solidifies deep
within the
Earth’s crust.
What is
Intrusive
Igneous
Rock?
Magma that
intrudes, or
pushes, into
surrounding rock
below the Earth’s
surface and cools.
What is
Intrusive
Igneous
Rock?
Usually has a coarsegrained texture
because it is well
insulated by
surrounding rock
and cools very
slowly. The minerals
that form are large,
visible crystals.
What are the
different
masses of
intrusive
igneous rock
named and
why?
Plutons
Batholiths
Stocks
Dikes
Masses of intrusive
igneous rock are
named for their size
and shape
Plutons
Plutons are large, irregular-shaped
intrusive bodies.
Batholiths
The largest of all igneous intrusions
are batholiths.
Stocks
Stocks are intrusive bodies that
are exposed over smaller areas
than batholiths.
Dikes
Dikes sheetlike intrusions that cut
across previous rock units.
Sills
Sills are sheetlike intrusions that
are oriented parallel to previous
rock units.
PLUTONS
Where
would I find
Extrusive
Igneous
Rock?
Magma that erupts, or
extrudes, onto the
Earth’s surface.
Extrusive rock is
common around
volcanoes.
What type
of texture
do
extrusive
igneous
rock have?
Lava cools
quickly on the
surface and
contains very
small crystals or
no crystals.
Does lava
always
come from
volcanoes?
Lava does not
always flow from
volcanoes.
Sometimes lava
erupts and flows
from long cracks in
the Earth’s crust
called fissures.
Where
do we
find
fissures?
Lava flows from fissures on
the ocean floor at places
where tension is causing the
ocean floor to be pulled
apart.
When a large amount of
lava flows out of fissures
onto land, the lava can
cover a large area and
form a plain called a lava
plateau.
Sedimentary Rock
Pg 44 in nb
Pg 102 in tb
What You Will Learn
• Describe the origin of sedimentary rock.
• Describe the three main categories of
sedimentary rock.
• Describe three types of sedimentary
structures.
What are the
origins of
Sedimentary
Rocks?
Rock and mineral
fragments called
sediment
sediment
plume from
Moore Creek
entering Dog
River.
http://www.usouthal.edu/geography/fearn/480page/98Gerrit/SedPlume.html
What are
the agents
of
weathering
that make
sediment?
1.
2.
3.
4.
5.
Wind
Water
Ice
Sunlight
Gravity
How do
sediments
move
from one
place to
another?
Through the
process of
erosion.
1. Layers of sediment are
deposited, they cover older
layers.
How are
sedimentary
rocks
formed?
2.
Older layers become
compacted.
3.
Dissolved minerals separate
from water that passes
through the sediment.
4.
Dissolved minerals form a
natural cement
5. Cement binds the rock and
mineral fragments together.
Sedimentary rock forms
at or near the Earth’s
surface. It forms without
the heat and pressure
that are involved in the
formation of igneous and
metamorphic rocks.
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What
is
strata?
Layers of
sedimentary
rock.
http://davidkanaga.blogspot.com/2011/07/sediments-and-sedimentary-rocks.html
How is
sedimentary
rock is
classified?
Sedimentary rock is
classified by the way it
forms.
Clastic, Chemical,
and Organic
What is
clastic
Sedimentary
Rock?
Clastic sedimentary
rock is made of
fragments of rocks
cemented together by
a mineral such as
calcite or quartz.
How is
clastic
sedimentary
rock is
classified?
By the size of the
fragments from which
the rock is made.
Pg 103
How is
chemical
sedimentary
rock
formed?
Chemical
sedimentary rock
forms from
solutions of
dissolved minerals
and water.
Halite, one type of chemical sedimentary rock,
is made of sodium chloride, NaCl, or table salt.
What is
Organic
Sedimentary
Rock and
what are
some
examples.
Limestone forms from the
remains, or fossils, of animals
that once lived in the ocean.
Coal forms underground
when partially decomposed
plant material is buried
beneath sediment and is
changed into coal by
increasing heat and pressure.
fossiliferous
limestone
c
o
a
l
What are
some
Sedimentary
Rock
Structures?
Stratification is the process in
which sedimentary rocks are
arranged in layers.
Ripple marks, record the
motion of wind and water
waves on lakes, oceans, rivers,
and sand dunes in features
called Structures called mud
cracks
ripple marks
Mud Cracks
http://www.answersincreation.org/curriculum/geology/geology_chapter_6.htm
Metamorphic rocks
pg 106 text
pg 48nb
Origins of
Metamorphic
Rock
If the temperature or pressure
of the new environment is
different from the one in
which the rock formed, the
rock will undergo
metamorphism.
The word metamorphism comes
from the Greek words
meta, which means “changed,”
morphos, which means “shape.”
Texture and
structure of
metamorphic
rocks
Contact metamorphism is a
change in the texture or structure
of a rock resulting from the
contact of invading magmatic
material.
Texture and
structure of
metamorphic
rocks
Regional
metamorphism is
metamorphism that
affects rocks over
large areas, instead
of in only a local
area.
107
p107
Hornfels is a fine-grained nonfoliated
metamorphic rock with no specific
composition. It is produced by contact
metamorphism. Hornfels is a rock that was
"baked" while near a heat source such as a
magma chamber, sill or dike.
Regional
metamorphic
area
http://www.geol.umd.edu/~jmerck/geol100/lectures/16.html
The minerals calcite, quartz,
and hematite combine and
recrystallize to form the
metamorphic mineral garnet.
P.108
index minerals,
Scientists can understand a metamorphic
rock’s history by observing the minerals
the rock contains. Theses minerals are
called index minerals
p108
Foliated.
Textures of
Metamorphic
Rock
The texture of
metamorphic rock in
which the mineral
grains are arranged
in planes or bands
Nonfoliated.
Textures of
Metamorphic
Rock
The texture of
metamorphic rock in
which the mineral
grains are not
arranged in planes or
bands
The effects of
metamorphism depend
on the heat and pressure
applied to the rock. see
what happens to shale, a
sedimentary rock, when it
is exposed to more and
more heat and pressure.
. Pg 109
Metamorphic
Rock
Structures
Deformation is a
change in the shape
of a rock caused by a
force placed on it.
These forces may
cause a rock to be
squeezed or
stretched.
These large folds occur in metamorphosed
sedimentary rock along Saglet Fiord in
Labrador, Canada
Slate is a fine-grained, foliated metamorphic
rock that is created by the alteration of shale
or mudstone by low-grade regional
metamorphism
Shale sedimentary rock
created by the alteration of shale or
mudstone by low-grade regional
metamorphism
Slate metamorphic rock
Gneiss is foliated metamorphic rock that has a
banded appearance and is made up of
granular mineral grains.
Granite
igneous
rock
Gneiss
metamorphic
rock
Marble is a non-foliated metamorphic rock
that is produced from the metamorphism of
limestone.
Limestone
sedimentary
rock
Marble
metamorphic
rock
Quartzite is a non-foliated metamorphic rock
that is produced by the metamorphism of
sandstone. It is composed primarily of quartz.
Sandstone
sedimentary rock
Quartzite
metamorphic rock