Transcript () earth`s surface

IGNEOUS ROCKS
Solid Rock
Igneous Rocks
() rocks form when molten (liquid) rock cools
and hardens.
Igneous means, “() formed”
() igneous rock -
Rock that forms from magma inside Earth.
() is molten (liquid) material () the
surface of Earth.
MAGMA VS. LAVA
Magma – molten material ()
the surface of the Earth
Lava – molten material
() earth’s surface
Intrusive rock = () Earth
The () cooled and
solidified
INSIDE Earth
into an intrusive
igneous rock
Extrusive igneous rock -
Rock that forms from lava on the () of Earth.
Molten (liquid) material at the
surface of Earth is called ().
Extrusive rock = () Earth
Extrusive rock is
also called ()
rock.
The lava cooled and
solidified () it exited
Earth into an extrusive
igneous rock
When () or () cools it () (a fancy
word for something becoming a
solid). When this happens
crystals form. Solidification
can also be called ().
The rocks crystals are minerals.
The size of the mineral crystals
that form in an igneous rock
depend on the (
).
As a general rule, the () a rock
takes to cool, the () the mineral
grains will become.
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As a result…
COOLED FAST at the surface,
so either there are no () or they
are so () they are not visible.
COOLED SLOW () the surface,
so () minerals have time to
grow.
Igneous Rocks and cooling rates;
Intrusive Rocks (slow () ) = large ()
Igneous Rocks and cooling rates;
Extrusive Rocks (() cooling) = () grains
Lava exposed at the surface
cools very fast so no
minerals can grow, it looks ()
or has ().
Earth’s surface
Deep in Earth’s crust
If it cools () the
surface it grows ()
mineral crystals but
not big enough to
see.
Earth’s surface
Deep in Earth’s crust
As you get deeper
into Earth’s crust
magma cools slower.
This allows ()
crystals to grow.
Earth’s surface
Deep in Earth’s crust
Really deep in Earth’s crust
magma cools really, really
(). This allows mineral
crystals to grow really,
really ().
Earth’s surface
Deep in Earth’s crust
Pop quiz hot shot!!!
Which
is the intrusive
rock and
Extrusive
Intrusive
which is the extrusive rock?
Fine grained
Basalt
Large crystals
Granite
Reference Tables page 6
Scheme for Igneous Rock
Identification
Determining the properties of an
igneous rock then identifying it.
HOLD ON A SECOND…
What is the definition of
texture when we are talking
about rocks?
() – How the rock’s surface looks due the
mineral grain ().
Grain Size
Non vesicular = No bubbles
Bubbles
The mineral crystal size
Where
Exited
the rock
Earth
formed
Where the rock formed
Inside
Earth
Lets see
what these
words mean.
Felsic
Mafic
Contains aluminum
Contains magnesium & ()
() colored
Dark colored
Typical continental rock
composition
Typical () rock
composition
Practice identifying
igneous rocks #1
Lets try to identify an
unknown igneous rock
Observed
properties of the
unknown rock:
Use the
E.S.R.T.
1. Light colored
2. Low Density
3. Fine Grained
4. Non vesicular (No gas bubbles)
4. Non3.Vesicular
1.2.
Fine
Light
Low
Grained
density
colored
(Nogas bubbles)
All the rock names
are located in this
area
The
Now
rock
Wewe
need
could
have
tobe
to
use
any
see
texture
in
where
the highlighted
to
all narrow
our known
itarea,
properties
according
meet
down
toin
color
further
the and
rockdensity
name area
The texture was fine and non vesicular
The only place
these two
textures match
is right here
The correct rock is located in the area
where all the properties overlap.
What do we think our
mystery rock is?
Yup, It is a sample
of Rhyolite, an
extrusive igneous
rock
Identifying any other
igneous rock works
the same way!!!
Now lets take our sample of
rhyolite and find out what its
mineral composition is.
If you do not know where in the rock rectangle
to go, assume it is right in the ().
Middle
Here are the
mineral
composition
percentages
All of this
equals 100%
of the rock’s
mineral
composition.
We now want to find
the individual mineral
percentages in our
sample of rhyolite
We now want to find
the individual mineral
percentages in our
sample of rhyolite
24% Potassium
Feldspar
We now want to find
the individual mineral
percentages in our
sample of rhyolite
36% Quartz
We now want to find
the individual mineral
percentages in our
sample of rhyolite
21% Plagioclase
Feldspar
We now want to find
the individual mineral
percentages in our
sample of rhyolite
10% Biotite
We now want to find
the individual mineral
percentages in our
sample of rhyolite
8% Amphibole
Now we know the mineral
composition of rhyolite is;
25% Potassium Feldspar
38% Quartz
20% Plagioclase Feldspar
9% Biotite
8% Amphibole
100%
All the minerals in the
rock are accounted for
Characteristics of Igneous Rocks
1. Tightly () mineral crystals (unless
it looks glassy).
Characteristics of Igneous Rocks
2. Intrusive Rocks, formed ()
inside Earth, have visible
(sometimes very ()) ().
Characteristics of Igneous Rocks
3. Extrusive rocks, formed () on the
() of Earth, will have a () or () texture.