Download igneous rock

An Introduction
What does a rock want to be
when it grows up?
A ROCK STAR
We’ve already
learned about
something called
the
WATER CYCLE
so we know a
cycle is a process
that
REPEATS
There are three types of rocks:
Igneous
Sedimentary
Metamorphic
Sediments
Magma Pool
Lava
The Rock Cycle . . .
is a group of changes
The ROCK CYCLE is NOT a circular cycle but rather a
process by which one rock changes into another which
can take billions of years.
What do you do to a
baby rock?
ROCK IT!
Types of Rocks
1.
2.
3.
Did you know?
Name
Period
Date
Did you know?
• Rocks are made up of one or more minerals and
have been formed by heat or pressure in the earth
• 95% of the Earth’s crust is igneous rock and
metamorphic rock
• Sedimentary rock is less than 5% of the Earth’s crust
but it covers 75% of the Earth’s continental surface
Classification
Rocks are classified by:
1. How they were formed
2. Composition – what the rock is made up of
3. Textures – sizes, shapes, and positions of grains
The ROCK CYCLE
H/P
W/E
Sedimentary
C/C
H/P
Magma
M
W/E
Sediments
M = Melting
C = Cooling
M
Metamorphic
W/E
W/E = Weathering & Erosion
H/P = Heat & Pressure
C
Igneous
C/C = Compacting & Cementing
What is a rock’s favorite
cereal?
Cocoa Pebbles
Igneous Rock
Rock that forms from the
cooling of magma or lava
Magma
Origins – How rock melts
1. Temperature increases
2. Composition changes = lowers the
melting point of the rock
3. Pressure on rock decreases
(pressure released)
Composition & Textures
The amount of time it takes for magma or lava to cool
determines the texture
Glue or paste your Composition & Texture table in
this section of your foldable
Formation of Igneous Rocks
Pyroclasts
Extrusive
Intrusive
Porphyry:
Fig. 5.3
partially
crystalline
Granite rocks are igneous rocks which were formed
by slowly cooling pockets of magma that were
trapped beneath the earth's surface. Granite is used
for long lasting monuments and for trim and
decoration on buildings.
Scoria rocks are igneous rocks which were formed
when lava cooled quickly above ground. You can see
where little pockets of air had been. Scoria is
actually a kind of glass and not a mixture of
minerals.
Pumice rocks are igneous rocks which were formed
when lava cooled quickly above ground. You can see
where little pockets of air had been. This rock is so
light, that many pumice rocks will actually float in
water. Pumice is actually a kind of glass and not a
mixture of minerals.
Obsidian rocks are igneous rocks that form when
lava cools quickly above ground. Obsidian is actually
glass and not a mixture of minerals.
How Igneous Rock Is Formed
Igneous rocks are called
fire rocks
and
are formed either
underground
or
above ground
Split the section labeled ROCK FORMATION into
two sections
Intrusive Igneous Rock
Underground – Inside
• Magma becomes trapped in small pockets
• Magma cools SLOWLY underground - bakes
•Usually coarse-grained
Extrusive Igneous Rock
Above ground - Outside
• Formed when volcanoes erupt
• Magma above the earth is called lava
• Lava cools QUICKLY above ground and in water
• Usually fine-grained
Magma is molten rock that is
deep underground
Magma forms “intrusive” igneous rock
Lava
forms
“extrusive”
igneous rock
Basalt is an extrusive igneous
rock that is very dark in color.
It is the most common type of
rock in the Earth's crust and it
makes up most of the ocean
floor.
This is an image of
the eruption of
Stromboli volcano
Sedimentary
Rock
Rock that forms when sediments are
compacted and cemented together
Origins of Sedimentary Rock
•Erosion - bits of earth
washed downstream and
settles to the bottom of the
rivers, lakes, and oceans.
•Eroded earth is deposited
on top of each other.
•Layers are pressed down and
turn into rock
Sandstone rocks are sedimentary rocks made from
small grains of the minerals quartz and feldspar. They
often form in layers as seen in this picture. They are
often used as building stones.
Limestone rocks are sedimentary rocks that are made
from the mineral calcite which came from the beds of
evaporated seas and lakes and from sea animal shells.
This rock is used in concrete and is an excellent building
stone for humid regions.
Shale rock is a type of sedimentary rock formed
from clay that is compacted together by pressure.
They are used to make bricks and other material
that is fired in a kiln.
Composition
1. Clastic – rock & mineral
fragments stick together.
The size & shape influences their
name
Cathedral Rock in Arizona is made of
a clastic rock called sandstone. .
These rocks are more than 250
million years old and are now being
weathered and eroded away by the
creek.
The rocks that make high
ridges are much more
resistant to weathering than
the surrounding rocks.
This stream carries sediment that has
weathered from mountains in Alaska
Sediment (A) may
someday become a
clastic rock (B) if
compacted and
cemented together.
2. Chemical Sedimentary Rock Forms when minerals
crystallize out of a solution
like sea water and becomes
rock
Conglomerate rocks are
sedimentary rocks. They are
made up of large sediments like
sand and pebbles. The sediment
is so large that pressure alone
cannot hold the rock together; it
is also cemented together with
dissolved minerals.
Gypsum rocks are sedimentary
rocks made up of sulfate mineral
and formed as the result of
evaporating sea water in massive
prehistoric basins. It is very soft and
is used to make Plaster of Paris,
casts, molds, and wallboards.
These pebbles were deposited in a
stream that once flowed over this area
in Indiana thousands of years ago.
Ripples in beach sand ,
such as those in the upper
photograph (A) may
someday become a rock
like the sandstone in the
lower photograph (B).
This sandstone was part of
a beach over 200 million
years ago in the Triassic
period.
3. Organic Sedimentary Rock -
Forms from the remains of organisms
Coquina
Structures
Features tell the story of formation
•Layers are called strata
•Strata differs depending on the kind, size and
color of the sediment
•The rate of deposition can affect the thickness of layers
What could affect the rate of deposition (deposits)?
The amount of rain – more = flooding & less = drought
•Weathering (wind & water) affects the design of
sedimentary rock
Weathering
(wind & water)
affects
the
design
of
sedimentary
rock
Metamorphic Rock
Rock that forms when the texture and composition of
pre-existing rock CHANGES due to heat or pressure
•The pre-existing
rock is often
referred to as
the
“Parent Rock”
Origins of Metamorphic Rock
Rocks that have
“MORPHED”
into another kind of rock
1. Contact Metamorphism –
Rock comes into
“contact” with magma
and cooks
2. Regional Metamorphism –
Enormous pressure builds
up in deeply buried rock
Schist rocks are metamorphic.
These rocks can be formed from
basalt, an igneous rock; shale, a
sedimentary rock; or slate, a
metamorphic rock. Through
tremendous heat and pressure,
these rocks were transformed into
this new kind of rock.
Gneiss rocks are metamorphic. These
rocks may have been granite, which is an
igneous rock, but heat and pressure
changed it. You can see how the mineral
grains in the rock were flattened through
tremendous heat and pressure and are
arranged in alternating patterns.
The more you try
to be gneiss, the
more you get
taken for granite!
Composition
Heat & Pressure
can cause
minerals in the
rock to
recrystallize
or
change!
Textures
Metamorphic rock is described by two types of
textures: Foliated and Non-foliated
1. Foliated – minerals are aligned and look like pages
in a book (A distinct pattern)
2. Non-Foliated – minerals don’t appear to be in any
pattern
Start
Apply increasing
heat
&
pressure
Finish
Here's a chart of some of
the key characteristics that
can help you identify the
rocks within these three
main classes.
Crystals: Small, flat surfaces that are shiny or
sparkly, like tiny mirrors.
Fossils: Imprints of leaves, shells, insects, or
other items in the rock.
Gas bubbles:
"Holes," like Swiss cheese, in the rock.
Glassy surface:
A shiny and smooth surface, like colored glass.
Ribbon-like layers: Straight or wavy stripes of
different colors in the rock.
Sand or pebbles: Individual stones, pebbles, or
sand grains visible in the rock.
Review:
There are how many types of rocks?
3
Rocks are put in one of these categories (classified) by
three things. What are they?
1. Composition
2. Texture
3. How it formed
Igneous rock is classified by composition - being light or
dark but we use what words?
Mafic or Felsic
Igneous rock is classified by texture – coarse-grained or
fine-grained but we use words to describe where they
formed. What words do we use?
Intrusive or Extrusive
Sedimentary rock is classified by composition – how it
was formed in one of three ways. What are the three
ways?
1. Clastic
2. Chemical
3. Organic
Metamorphic rock is classified by composition – What
minerals are present and by texture – but we describe
the texture based on the presence of a pattern or a lack
of a pattern. What words do we use to describe the
pattern or lack of a pattern?
Foliated or Non-foliated
Igneous rock forms how?
From the cooling and solidification of lava or magma
Sedimentary rock forms how?
From the erosion and weathering of rock
What type of rock can become sedimentary rock?
All types
Metamorphic rock forms how?
From intense heat & pressure changing pre-existing rock
The ROCK CYCLE
H/P
W/E
Sedimentary
C/C
H/P
Magma
M
W/E
Sediments
M = Melting
C = Cooling
M
Metamorphic
W/E
W/E = Weather & Erosion
H/P = Heat & Pressure
C
Igneous
C/C = Compaction & Cementation
The END!