Download Chapter 2 - MrJardina

Chapter 2
Rocks
Jardina-Conelway Elementary
Three Rock Types
 Igneous
 Sedimentary
 Metamorphic
Jardina-Conelway Elementary
Igneous Rocks: A Hot Item
 Rocks are made up of
minerals.
 The word igneous
comes from the Latin
word for “fire”
 Igneous rocks form
when hot, melted rock
material cools and
hardens.
 Molten rock that forms
deep below the earth is
called magma.
Jardina-Conelway Elementary
Igneous Rocks Formed From Magma
 Magma rises because it
is less dense than the
material around it.
 As it rises it sometimes
cools before it reaches
the surface.
 The magma cools
slowly, allowing mineral
grains or crystals to
form slowly…
 Mineral grains are large
in rocks formed from
Jardina-Conelway Elementary
magma.
Igneous Rocks Formed From Lava
 Magma that reaches
the earth’s surface is
called lava.
 An opening through
which lava flows is
called a volcano.
 When lava cools on the
earth’s surface it forms
igneous rocks.
Jardina-Conelway Elementary
Igneous Rocks – Lava Formed
 Lava cools much
quicker than magma
because it is on the
earth’s surface.
 How would this affect
Basalt Lava
the size of the
mineral
grains (crystals) found
in lava rocks compared
to rocks formed from
magma?
Basalt Lava
Rhyolite
Jardina-Conelway Elementary
Obsidian
Sedimentary Rocks: Rocks Formed
From Pieces
 Sedimentary rocks are
formed at earth’s
surface when
sediments harden into
rock.
 Sediments include bits
of rocks, minerals, and
organic materials (what
are organic materials?)
Jardina-Conelway Elementary
Types of Sedimentary Rocks
 Clastic: pieces of rocks, minerals, and organic
materials are cemented together.
 Chemical: form when water rich in dissolved
minerals evaporates, leaving the minerals
behind or when chemical changes form new
minerals.
 Organic: form from the remains of plants and
animals or from parts, such as shells, of
organisms.
Jardina-Conelway Elementary
Clastic Sedimentary Rocks
 Most clastic
sedimentary rocks form
when wind, water, or ice
carry and drop
sediments and then
they become
compacted or cemented
together.
 Cementation takes
place when the water
dries and the minerals
and loose sediment
bind together.
Jardina-Conelway Elementary
Chemical Sedimentary Rocks
 Rocks that form when
water rich in dissolved
minerals evaporates


Limestone is a "chemical"
sedimentary rock that is composed
mostly of calcite (CaCO3) that
precipitates from seawater.
Jardina-Conelway Elementary
Rock Gypsum- forms
when H²O evaporates.
Rock Salt- (almost
pure halite) is known to
you as table salt.
Organic Sedimentary Rocks
 Form from the remains
of plants and animals or
from parts (shells) of
organisms.
 Anthracite coal forms
when bits of dead
plants are compacted
over long periods of
time.
 The squeezing removes
the water and leaves
behind the carbon that
makes up the coal.
Jardina-Conelway Elementary
Metamorphic Rocks
 Metamorphic – “To Change
Form”
 Are like sedimentary rocks
because they form from
existing rocks
 Are like igneous rocks
because both kinds can form
at high temperatures and
pressures.
 So how are they different
than the other 2 types of
rocks that we have
discussed?
Jardina-Conelway Elementary
Metamorphic Rocks:
 Metamorphic rocks are
new rocks that form from
existing rocks because of
changes caused by heat,
pressure, or chemicals.
 Change from one type of
rock to another is
referred to as
metamorphism.

http://images.google.com/imgres?imgurl=
http://www.windows.ucar.edu/earth/geolo
gy/images/rock_cycle_ani4.gif&imgrefurl=
http://www.windows.ucar.edu/tour/link%3
D/earth/geology/rocks_intro.html&h=400
&w=238&sz=111&hl=en&start=19&tbnid=
6PSVuFyIO6sbbM:&tbnh=124&tbnw=74
&prev=/images%3Fq%3Dmetamorphic%
2Brock%2Bchange%26gbv%3D2%26svn
Jardina-Conelway Elementary
um%3D10%26hl%3Den
Changes in Metamorphism
 The changes that occur in metamorphism can result
from three different sets of conditions.



Contact Metamorphism- hot magma or lava comes in
contact with rock and gets “baked.” (change occurs
from just the heat)
Regional Metamorphism- occurs in rocks buried deep
below the earth’s surface where temp. and pressure
change the rocks texture and composition.
Burial Metamorphism- causes the least amount of
change, occurs when the weight of rocks and sediment
burying a rock put pressure on it.
Jardina-Conelway Elementary
Classifying Metamorphic Rocks
 M.R. are classified as
banded or nonbanded.
 Banded M.R.’s mineral
grains are lined due the
heat and pressure that
formed the rocks
 Nonbanded M.R.’s
texture is described as
massive and do not
have mineral grains
aligned.
Jardina-Conelway Elementary
All About Rocks and Minerals (23:20)
 ..\Videos\Basics_of_Geology__All_About_Ro
cks_and_Minerals.asf
Jardina-Conelway Elementary
Rock Quarries
 A quarry is a mine from
which rocks can be
removed.
 Rock is removed from
quarries in two forms
 Dimension stones- slabs
of rock removed for
specific shapes and
sizes.
 Crushed stone- bits and
pieces of rocks that are
primarily used in
concretes and cements.
Jardina-Conelway Elementary
A Ton of Bricks
 Bricks aren’t actually rocks
because they are not formed
by nature.
 Bricks are made from clays
and sediments.
 Bricks have been used by
people for over 60 centuries.
 How is the way that bricks
are created similar to that of
how metamorphic rocks as
well as sedimentary rocks
are formed?
Adobe Brick House
Jardina-Conelway Elementary
Coal: A Fossil Fuel
 A fossil fuel is a material
formed from plant or
animal remains that can
be burned for energy.
 Millions of years of high
temperatures and
pressure have
“squeezed” and
changed these remains
forming coal.
Jardina-Conelway Elementary
Types of Coal
 Bituminous Coal-
provides the most
energy of all the types
of coal, but is very
harmful to our
environment.
 Anthracite Coal- burns
much cleaner and
longer, but does not
provide as much
energy.
Jardina-Conelway Elementary
The Rock Cycle
Jardina-Conelway Elementary
The Rock Cycle
 Any kind of rock can change into another type
of rock and not just by metamorphism.
 Melting and pressure can change one rock
type to another. The series of changes that
rocks undergo is called the “Rock Cycle.”
Jardina-Conelway Elementary
From one type to another!!!
 Sedimentary to Metamorphic
 High temperatures and pressures within the earth
change sedimentary into metamorphic rocks.
 Metamorphic to Igneous
 The melting of rocks (metamorphic) into molten rock
and the cooling of them again into igneous rocks,
shows the change of yet another type of rock into
another.
 Igneous to Sedimentary
 Weathering is the breaking up of rocks into sediments.
Any igneous rocks the cool on the surface of the earth
can become sediment bits through the process of
weathering. The sediments are then compacted and
cemented together naturally to form sedimentary rocks.
Jardina-Conelway Elementary