Rocks and Minerals
EQ: What is a mineral?
Standard: S6E5.b
Investigate the contribution
of minerals to rock
composition.
EQ: How are minerals identified?
• What are the
characteristics of a
mineral?
• How are minerals
identified?
• What is the Mohs
hardness scale?
• What is the major
difference between an
element and a
compound?
Properties of Minerals
• A mineral is a naturally formed, inorganic
solid that has a crystal structure and a
definite chemical composition.
• Each mineral has its own set of specific physical
properties that can be used to identify it
(hardness, color, streak, luster, density, crystal
system, cleavage and fracture).
• An element is a substance composed of a
single kind of atom.
• A compound is two or more elements
combined so that the elements no longer
have their original distinct properties.
Properties of Minerals
• Naturally Formed- must form naturally
• Inorganic- cannot arise from materials that
were once part of a living thing
• Solid- always solid, with a definite volume
and a definite shape
• Crystalline Structure- particles must line up
in a pattern that repeats over and over again
• Definite Chemical Composition- always
contains certain elements in definite
proportions. NaCl (salt)
Identifying Minerals
• Hardness- Mohs hardness scale ranks ten
minerals from softest to hardest.
• Color- Because of factors, such as impurities,
used only to identify a few minerals
• Streak- the color of a mineral in its powdered form
• Luster- how a mineral reflects light from its
surface
• Density- the ratio of the mass to the volume of
a substance
• Crystal Systems- six groups of structures based
on the number and angle of the crystal faces
• Cleavage – splitting along smooth, flat surface
• Fracture- breaking apart along curved or irregular
surfaces
Special Properties
• Some properties are particular to only a few
types of minerals:
•
•
•
•
•
Fluorescence – glow under ultraviolet light
Chemical Reactions – reacts to an acid
Magnetism – natural magnets that attract iron.
Taste – ex. Halite has a salty taste
Optical Properties – some can cause a double
image
• Radioactivity – minerals that contain radium or
uranium
Mohs Hardness Scale
•
•
•
•
•
•
•
•
•
•
Talc
Gypsum
Calcite
Fluorite
Apatite
Orthoclase
Quartz
Topaz
Corundum
Diamond
1
2
3
4
5
6
7
8
9
10
Softest known mineral
fingernail can scratch it
scratched by copper penny
easily scratched by steel knife
can be scratched by steel knife
can scratch window glass
can scratch steel
can scratch quartz
can scratch topaz
hardest known mineral
Quick Check
•
1. Which of the following is NOT a
characteristic of a mineral?
a.
b.
c.
d.
It is formed in nature.
It is a living material.
It has a crystalline structure.
It is a solid.
Quick Check
•
2. Which of the following properties of
minerals does Mohs scale measure?
a.
b.
c.
d.
luster
density
hardness
streak
Quick Check
• 3. Pure substances cannot be broken
down into simpler substances by ordinary
chemical means are called
a. molecules.
b. compounds.
c. crystals.
d. elements.
Quick Check
• 4. Which of the following properties is
considered a special property that applies
to only a few minerals?
a. luster
b. taste
c. hardness
d. density
Quick Check
• 5. Which of the following substances is a
mineral?
a. fluorite, which is a crystalline solid with the
chemical formula CaF2
b. coal, which forms from the remains of living
things.
c. obsidian, which is a volcanic glass and is not
crystalline.
d. brass, which is a metal that is made by
humans.
EQ: What is a mineral?
• What is a crystal, and
what determines a
crystal’s shape?
• Describe the two
major groups of
minerals.
• What is a native
element?
Mineral Structure
• A mineral is a naturally formed, inorganic solid
that has a define crystalline structure.
• Minerals may be either elements or
compounds.
• Elements are pure substances that cannot be
broken down into simpler substances by ordinary
means.
• A compound is a substance made of two or
more elements that have been chemically joined
together.
• A mineral that is composed of only one element
is called a native element.
Crystals
• A crystal is a solid whose atoms, ions, or
molecules are arranged in a definite pattern.
• Crystals are solid, geometric forms produced
by a repeating pattern of atoms or molecules
that are present throughout the mineral.
• A crystal’s shape is determined by the
arrangement of the atoms or molecules within
the crystal.
• All minerals can be grouped into crystal
classes according to the kinds of crystals
they form.
Two Groups of Minerals
• Minerals are divided into two groups based on
their chemical composition.
• Silicate minerals are minerals that contain a
combination of the elements silicon and oxygen
(quartz, feldspar, mica).
• Silicate minerals make up over 90% of the
Earth’s crust.
• Nonsilicate minerals are minerals that do not
contain a combination of the elements silicon
and oxygen ( copper, calcite, fluorite, corundum,
gypsum, galena).
Quick Check
•
1. What are the two major groups of
minerals?
a.
b.
c.
d.
metallic and nonmetallic
native elements and carbonates
silicates and nonsilicates
quartz and mica
Quick Check
•
2. Silicate minerals contain a
combination of the elements
a.
b.
c.
d.
Sulfur and oxygen.
Carbon and oxygen.
Iron and oxygen.
Silicon and oxygen.
Quick Check
•
3. Which of the following is a nonsilicate
mineral?
a.
b.
c.
d.
orthoclase, KASi3O8
Talc, Mg3Si4O10(OH)2
Almandine, Fe3Al2(SiO4)3
Magnetite, Fe3O4
The Formation, Mining, and Use of
Minerals (p.74)
• Where can you find
minerals?
• What is an ore?
• Compare surface and
subsurface mining.
• What is reclamation?
• What are some examples
of minerals and their
uses?
The Formation of Minerals
• Minerals form in a variety of environments
in Earth’s crust.
• Each of these environments has a
different set of physical and chemical
conditions.
• The environment in which a mineral forms
determines the mineral’s properties.
• Environments in which minerals form may
be on or near Earth’s surface or deep
beneath Earth’s surface.
The Environments
Evaporating Salt Water
• When a body of salt water dries up,
minerals are left behind.
-gypsum, halite
Metamorphic Rocks
• When changes in temperature, pressure,
or chemical make-up changes a rock,
metamorphism takes place.
• -calcite, garnet, graphite, hematite,
magnetite, mica, and talc
The Environments
Limestones
• Surface water and ground water carry dissolved
materials to lakes and seas where they
crystallize on the bottom
-Calcite, dolomite
Hot-Water Solutions
• Groundwater works its way downward and is
heated by magma. It then reacts with minerals
to form a hot liquid solution.
-gold, copper, sulfur, pyrite, galena
The Environments
Pegmatites
• As magma moves upward, it can form teardropshaped bodies called pegmatites. The mineral
crystals become extremely large.
-many gemstones, such as topaz, tourmaline
Plutons
• As magma rises upward through the crust, it
sometimes stops moving before it reaches the
surface and cools slowly, forming millions of
mineral crystals. The entire magma body
solidifies to form a pluton.
– Mica, feldspar, magnetite, quartz
Mining
• An ore is the natural material large enough and
pure enough to be mined for profit.
• Rocks and minerals are removed from the
ground by one of two methods-surface mining
and subsurface mining.
• Surface mining is used to remove mineral
deposits on or near the Earth’s surface.
- open pits
- surface coal mines (open-pit)
- quarries
Mining
• Subsurface mining is used when mineral
deposits are located too deep within Earth to be
surface mined.
• Mine reclamation is the process by which land
used for mining is returned to its original state or
better.
• Has been required by law since the mid-1970’s.
• To reduce the effects of mining, reduce our need
for minerals.
• Recycle!
The Use of Minerals
• Some minerals are of major economic and
industrial importance.
• Metallic minerals have shiny surfaces, do
not let light pass through them, good
conductors of heat and electricity.
• Nonmetallic minerals have shiny or dull
surfaces, may let light pass through them,
and are good insulators of electricity.
The Use of Minerals
• Gemstones are highly valuable minerals
because of their beauty and rarity rather
than their usefulness.
• Color is the most important characteristic
of a gemstone.
• The more attractive the color is, the more
valuable the gem is.
• Mass of a gem is expressed in a unit
known as a carat.
• One carat is equal to 200 mg.
Common Uses of Minerals
Mineral
Uses
Copper
Electrical wires, plumbing, coins
Diamond
Jewelry, cutting tools, drill bits
Galena
Batteries, ammunition
Gibbsite
Cans, foil, appliances, utensils
Gold
Jewelry, computers, spacecraft, dentistry
Gypsum
Wallboards, plaster, cement
Halite
Nutrition, highway de-icer, water softener
Quartz
Glass, computer chips
Silver
Jewelry, photography, electronic products
Sphalerite
Jet aircraft, spacecraft, paints
Quick Check
• In a mineral, the particles line up in a
repeating pattern to form
•
•
•
•
A.
B.
C.
D.
an element
a crystal
a mixture
a compound
Quick Check
• The term that describes how a mineral
reflects light is its __________.
•
•
•
•
A. luster.
B. streak
C. color.
D. weight.
Quick Check
• One characteristic that a substance must
have to be considered a mineral is _____.
•
•
•
•
A. to be living.
B. to be small.
C. to a liquid.
D. to be a solid.
Quick check
• A compound is two or more ________
chemically combined.
•
•
•
•
A. atoms
B. minerals
C. elements
D. protons
Quick Check
• An element is a substance composed of a
single kind of __________.
•
•
•
•
A. compound.
B. atom.
C. mineral.
D. Mohs hardness scale.
Quick Check
•
The groupings silicate and nonsilicate
minerals are based on
a.
b.
c.
d.
Organic content.
Gas and liquid state
Chemical composition.
Color.
Quick Check
•
Nonsilicate minerals
a.
b.
c.
d.
Do not contain oxygen.
Include native elements.
All have a nonmetallic luster.
Are all rare substances.
Quick Check
Which of the following is NOT a class of
nonsilicate minerals?
a.
b.
c.
d.
oxides
Micas
carbonates
native elements
Quick Check
What is a mineral deposit that is large and
pure enough to be mined called?
a.
b.
c.
d.
gemstone
ore
pluton
pegmatite
Quick Check
Halides form when fluorine, chlorine, or
bromine combine with any of the
following elements EXCEPT
a.
b.
c.
d.
sodium.
potassium.
calcium.
oxygen.
Quick Check
•
What is the name for nonmetallic
minerals that are valued for their beauty
and rarity rather than their usefulness?
a.
b.
c.
d.
plutons
gemstones
ores
pegmaites
Quick Check
•
What kinds of mines are open pit and
quarry mines?
a.
b.
c.
d.
shaft mines
slope mines
surface mines
subsurface mines
ROCK: Mineral Mixtures
EQ: How are rocks
formed?
Standard S6E5.c
Classify rocks by their
process of formation.
How are rocks classified?
• How are rocks classified?
• How does igneous rock
become sedimentary rock?
• How does sedimentary
rock become metamorphic
rock?
• How does metamorphic
rock become igneous
rock?
Rock Formation
• Scientists classify rocks by the way they
are formed.
• Rocks are composed of minerals and other
materials.
• Minerals are the building blocks of rocks.
• Rocks are classified into three (3) groups
based on how they are formed:
– Sedimentary rocks
– Igneous rocks
– Metamorphic rocks
The Rock Cycle
• What materials are
rocks made of?
• Describe four
processes that
change rock from one
type to another.
• What are the three
main classes of rock?
• Describe two
characteristics of rock
that are used to help
classify it.
What materials are rocks made of?
• Rock is describe as a naturally occurring solid mixture of
one or more minerals and organic matter.
• Rocks are made of mixtures of minerals and other
materials, although some rocks may contain only a single
mineral. When studying a rock sample, geologists
observe the rock’s color and texture and determine its
mineral composition.
• Texture is described with terms based on grain size, grain
shape, and grain pattern. Most rocks are made up of tiny
particles of minerals or other rocks, which are called
grains. A rock’s grains give it its texture.
• There are three major groups of rocks: igneous rock,
sedimentary rock, and metamorphic rock. These terms
refer to how the rocks in each group were formed.
The Rock Cycle
• The rock cycle is a series of processes in
which a rock forms, changes from one
type to another, is destroyed, and forms
again by geological processes.
• Rocks have been used by humans to
make tools and weapons and to construct
buildings.
Processes That Shape the Earth
• Certain geological processes make and
destroy rock.
• These processes shape the features of the
Earth.
• Theses processes also influence the type
of rock that is found in a certain area of
Earth’s surface.
Processes That Shape the Earth
• Weathering is the process by which water,
wind, ice, and heat break down rock.
• Erosion is the process by which sediment
is removed from its source.
• Deposition is the process by which
sediment moved by erosion is laid down.
• Uplift is the process by which rock within
the Earth moves to Earth’s surface.
Illustrating the Rock Cycle
• Igneous rock is formed when magma or
lava is cooled and hardens and solidifies.
• Sedimentary rock is formed by the process
of weathering, erosion, deposition and
cementation.
• Metamorphic rock is formed by heat,
pressure or chemical change beneath
Earth’s surface.
Rock Classification
• Scientists classify rocks in detail by using
two important criteria – composition and
texture.
• Composition is the chemical makeup of a
rock; describes either the minerals or other
materials in the rock.
• Texture is the quality of a rock based on
the sizes, shapes, and positions of the
rocks grains.
Classifying Rocks
I.
Classifying Rocks - How Geologists Classify Rocks = When studying a rock sample, geologists
observe the rock’s origin, color and texture, and determine its mineral composition
A. Origin = 3 major groups of rocks
1. igneous rock = forms from the cooling of molten rock
a. lava = above the surface
b. magma = below the surface
2. sedimentary rock = forms in layers from other rocks, plants, and animals that
have been compacted and cemented together
3. metamorphic rock = formed when existing rock is changed by heat, pressure, or
chemical reactions
B. Texture = the size, shape, and pattern of the rock’s
grains
1. Grain Size
a. fine-grained (small)
b. coarse-grained (large)
2. Grain Shape
a. smooth and rounded
b. jagged
3. Grain Pattern
a. lie in flat layers
b. wavy, swirling patterns
c. looks like rows of multicolored beads
d. occur randomly
4. No Visible Grain
a. have no apparent grains
b. smooth, shiny texture
C. Mineral Composition =
1. mafic
Quick Check
1. Which of the following rocks is not
normally used as a construction
material?
a.
b.
c.
d.
marble
halite
limestone
granite
Quick Check
The process in which wind, water, ice, and
heat break down rock is called
a.
b.
c.
d.
uplift.
intrusion.
recystallization.
weathering.
Quick Check
What forms when rock partially or
completely melts?
a.
b.
c.
d.
limestone
reefs
ripple marks
magma
Quick Check
Scientists classify rocks
a.
b.
c.
d.
by composition and texture.
by volume.
by mass.
by color and size.
How do igneous rocks form?
• What characteristics are
used to classify igneous
rocks?
• Describe three (3) ways in
which igneous rocks differ?
• What is the difference
between extrusive and
intrusive rocks? Give an
example of each.
• Why are some igneous rocks
dark and others light?
Origins of Igneous Rock
• Igneous rocks are classified by their origin
of formation, texture of the grains, and
composition of the rock.
• Igneous rock forms when magma cools
and hardens.
• Three ways magma can form: heat/rise in
temperature, pressure released, rock
changes composition.
Origins of Igneous Rock
• Igneous rocks form from melted rock, the cooling
and hardening of magma and lava.
• Magma is molten rock beneath Earth’s surface.
• Lava is molten rock above Earth’s surface.
• When a volcano erupts, magma is released onto
Earth’s surface.
• Once above Earth’s surface, it is called lava.
• Common igneous rocks: granite, basalt, pumice,
obsidian.
Composition and Texture of Igneous
Rock
• Igneous rocks differ from one another in
what they are made of and how fast they
are cooled.
• Composition –
• Igneous rock that is rich in silicon and
light-colored are called felsic rock.
• Igneous rock that is poor in silicon and
dark-colored are called mafic rock.
• Texture –
– Fine-grained (small) = cools quickly
– Coarse-grained (large) =cools slowly
Origins of Igneous Rock
• Igneous rocks are classified by their origin of
formation, texture of the grains, and
composition of the rock.
• Igneous rock forms when magma cools and
hardens.
• Three ways magma can form:
– heat/rise in temperature
– pressure released
– rock changes composition
Composition and Texture of Igneous
Rock
• Igneous rocks differ from one another in what
they are made of and how fast they are
cooled.
• Composition –
• Igneous rock that is rich in silicon and lightcolored are called felsic rock.
• Igneous rock that is poor in silicon and darkcolored are called mafic rock.
• Texture –
– Fine-grained (small) = cools quickly
– Coarse-grained (large) =cools slowly
Origin of Formation
• Igneous rock formations are located below
and above Earth’s surface.
• Intrusive igneous rock – from magma
(below surface), coarse-grained (large
crystals), below Earth’s surface
• Extrusive igneous rock – from lava (above
surface), fine-grained (small crystals),
below Earth’s surface
How do igneous rocks form?
• Igneous rocks are classified according to their origin, texture,
and mineral composition.
• Igneous rocks form either from lava, above the earth’s surface
or magma, below the earth’s surface. They also differ in texture
according to the size and shape of their mineral grains. They
differ in mineral composition depending on how much silica and
other minerals are present.
• Extrusive rock (basalt) forms from lava that has erupted onto
Earth’s surface.
• Intrusive rock (granite) forms when magma hardens beneath
Earth’s surface.
• Dark igneous rocks form from magma or lava low in silica
content (felsic).
• Light igneous rocks form from magma high in silica content
(mafic).
Composition and Texture of Igneous
Rock
• The longer it takes for magma or lava to cool,
the more time the crystals have to grow.
• The larger the crystals or grains, the more
coarse the texture of the rock.
• The less time liquid rock takes to cool, the less
time crystals have to grow.
• This type of rock will be fine-grained.
• Fine-grained rocks contain very small crystals or
grains.
• If the cooling is very rapid, it contains no
crystals.
Intrusive Igneous Rock
• Igneous rock that forms below the surface
of the earth
• Below = intrusive
• Usually has coarse-grain texture
• Cools very slowly
• Common intrusive igneous rocks are
called Plutons.
Extrusive Igneous Rock
• Igneous rock that forms above the earth’s
surface
• Extrusive = above
• Common around volcanoes
• Cools quickly
• Usually fine-grained texture
• Lava cools to form the ocean floor
Uses of Igneous Rock
• Most igneous rocks are hard, dense, and durable.
• Ancient Native Americans used obsidian for making
very sharp tools for cutting and scraping.
• Granite is used as a building material such as
decorative stonework, curbstones, and floors..
• Basalt is crushed to make gravel.
• The rough surface of pumice makes a good abrasive
for cleaning and polishing.
• Perlite is often mixed with soil for strating vegetable
seeds.
Summary
• Igneous rock forms when magma
cools and hardens
• The texture of igneous rock is
determined by the rate at which the
rock cools
• Igneous rock that solidifies at Earth’s
surface is extrusive. Igneous rock
that solidifies within Earth’s surface is
intrusive.
Quick Check
1. Which of the following are ways magma is
formed?
a.by compaction and cooling
b.by melting and cooling
c.by changes in composition
d.by weathering and erosion
Quick Check
2. What kind of texture does igneous rock
have when magma cools slowly?
a.
b.
c.
d.
coarse-grained
large-grained
fine-grained
medium-grained
Quick Check
3. What kind of texture does igneous rock
have when magma cools rapidly?
a.
b.
c.
d.
coarse-grained
medium-grained
large-grained
fine-grained
Quick Check
4. What kind of rock is formed when magma
intrudes into other rock?
a.extrusive igneous rock
b.sedimentary rock
c.intrusive igneous rock
d.organic sedimentary rock
Quick Check
5. What kind of rock is formed from lava that
cools on Earth’s surface?
a. organic sedimentary rock
b. sedimentary rock
c. intrusive igneous rock
d. extrusive igneous rock
How is sedimentary rock formed?
• Describe the origin of
sedimentary rock.
• Describe the three
main categories of
sedimentary rock.
• Describe three types
of sedimentary
structures.
Forming of Sedimentary Rock
• Sedimentary rocks are formed
when particles of other rocks or
the remains of plants and
animals are pressed and
cemented together.
• Rocks undergo weathering to
form sediment.
• Sediment is transported
(erosion), settled out of the
wind and water and deposited
somewhere.
• Usually after burial somewhere,
the deposited sediment
undergoes lithification.
Forming of Sedimentary Rock
• Lithification is the process that turns sediment
into a rock.
• If the sedimentary rock is buried deep in to the
crust under more and more sediment (layered),
often due to plate tectonics, the heat and
pressure causes metamorphism to occur.
• This transforms the sedimentary rock into a
metamorphic rock.
• Sediment (weathering) = erosion = deposited =
compaction = cementation.
• Common Sedimentary Rock: sandstone, shale,
and limestone.
Forming of Sedimentary Rock
• Erosion – occurs when running water or wind
loosen and carries away fragments of rock.
• Deposition- the process in which sediment
settles out of the water or wind carrying it.
• Compaction- the process that presses sediment
together.
• Cementation- the process in which minerals
crystallize and glue particles of sediment
together.
Forming of Sedimentary Rock
• Sedimentary rocks are formed when small
particles of rock and the remains of plants and
animals are compacted and cemented together.
• To form sedimentary rocks, sediment is
loosened and carried away by water and wind
by erosion.
• The sediment then settles out of the wind and
water during deposition.
• The sediment begins to settle out and form
layers. As the layers stack up, they become
heavier until the weight squeezes the layers
tighter during compaction.
Composition of Sedimentary Rock
• Sedimentary rock is classified by the
way it forms.
• Clastic – formed from other rocks and
minerals (conglomerate, sandstone, shale)
• Chemical – forms when minerals
crystallize out of solutions (halite)
• Organic – forms from the remains of onceliving things (limestone).
Types of Sedimentary Rock
• Geologists classify
sedimentary rocks
according to the type of
sediments that make up
the rock.
• There are three major
groups of sedimentary
rocks: clastic rocks,
organic rocks, and
chemical rocks.
Clastic Rocks
• A clastic rock is a
sedimentary rock that
forms when rock
particles are squeezed
together.
• Examples of clastic
rocks:
–
–
–
–
Shale
Sandstone
Conglomerate
Breccia
Clastic Rock: Shale
• Shale forms from tiny
particles of clay.
• Shale feels smooth, and
splits easily into flat
pieces
Clastic Rock: Sandstone
• Sandstone forms from
the sand on beaches, on
the ocean floor, in
riverbeds, and in sand
dunes.
• Sandstone is formed
when small particles of
sand are pressed and
cemented together.
Clastic Rock: Conglomerate and Breccia
• Conglomerate is a
rock made up of large
particles with rounded
edges.
• Breccia is a rock
made up of large
fragments with sharp
edges.
Organic Rocks
• Organic rock forms from
the remains of plants
and animals and are
deposit in thick layers.
• The term “organic” refers
to substances that were
once part of living things.
• Three important organic
rocks:
– Coal
– Limestone
– Chalk
Organic Rock: Coal
• Coal forms from the
remains of swamp
plants buried in water.
• Over millions of
years, they slowly
change into coal.
Organic Rock: Limestone
• The hard shell of
living things
produces
limestone.
• Chalk forms from
sediments made of
skeletons of
microscopic living
things found in the
ocean.
Chemical Rocks
• Chemical rock forms
when minerals that are
dissolved in a solution
crystallize.
• Chemical rocks can
also form when mineral
deposits left when seas
or lakes evaporate.
• Examples:
– Rock salt
– gypsum
Sedimentary Rock Structures
• The most important feature of sedimentary rock is
stratification.
• Stratification is the process in which sedimentary
rocks are arranged in layers.
• Strata differ from one another depending on the kind,
size, and color of their sediment.
• Ripple marks (1) are made by the motion of wind and
water waves on lakes, oceans, rivers, and sand dues.
• Mud cracks (2) form when fine-grained sediments at
the bottom of a shallow body of water are exposed to
air and dry out.
• Rain-drop (3) impressions can be preserved in finegrained sediments, as small pits with raised rims.
Uses of Sedimentary Rocks
• Sandstone and limestone are used as
building materials.
• The White House in Washington, D.C. is
built of sandstone.
• Limestone is also used to make cement.
Summary
• Sedimentary rock forms from rock weathering
into sediment, erosion, deposition, compaction
and cementation.
• Sedimentary rock forms at or near the Earth’s
surface.
• Clastic sedimentary rock forms when rock or
mineral fragments are cemented together.
• Chemical sedimentary rock forms from solutions
of dissolved minerals and water.
• Organic (limestone) forms from the remains of
plants and animals.
Quick Check
1. Which process forms sediment/
a.
b.
c.
d.
weathering
cementation
compaction
deposition
Quick Check
2. What are strata?
a.mineral fragments
b.minerals crystallized out of solution
c.layers in sedimentary rock
d.fossils in sedimentary rock
Quick Check
3. What kind of sedimentary rock is
made of fragments of rocks
cemented together by a mineral?
a.
b.
c.
d.
organic
stratified
chemical
clastic
Quick Check
4. What kind of sedimentary rock is
made from solutions of dissolved
minerals in water?
a.
b.
c.
d.
organic
chemical
stratified
clastic
Quick Check
5. What kind of sedimentary rock is
made from fossils?
a.
b.
c.
d.
organic
stratified
chemical
clastic
Quick Check
6. What is the process called in which
sedimentary rocks are arranged in
layers?
a.
b.
c.
d.
erosion
extrusion
weathering
stratification
How is metamorphic rock formed?
• How are metamorphic
rocks formed?
• Describe two ways a
rock can undergo
metamorphism.
• Describe the
difference between
foliated and
nonfoliated
metamorphic rock.
Metamorphic Rocks
• Metamorphic rock is formed when existing rock
is changed by heat, pressure, or chemical
reactions.
• They are classified by the arrangement of their
mineral grains.
• The two types of metamorphic rocks are called
foliated and non-foliated.
• Foliated is when the grains are parallel or
arranged in planes or bands.
• Non-foliated refers to where the grains are
arranged randomly.
How Do Metamorphic Rocks Form?
• Heat and pressure deep beneath Earth’s surface
can change any rock into metamorphic rock.
• When a rock changes into metamorphic rock, its
texture, crystal structure, and mineral content change.
• The texture or mineral composition of a rock can
change when its surroundings change.
• If the temperature or pressure of the new environment
is different from the one in which the rock formed, the
rock will undergo metamorphism.
• Two ways that rock can undergo metamorphism are
by contact metamorphism and regional
metamorphism.
Composition of Metamorphic Rock
• Metamorphism occurs when temperature
and pressure inside the Earth’s crust
change.
• Minerals that were present in the rock
when it formed may not be stable in the
new temperature and pressure conditions.
• The original minerals change into minerals
that are more stable in these new
environment.
• Some metamorphic minerals form only at
certain temperatures and pressures.
• Common metamorphic rock: slate, schist,
marble, and gneiss.
Textures of Metamorphic Rock
• Geologists classify metamorphic rocks by the
arrangement of the grains that make up the
rocks.
• Metamorphic rocks that have their grains
arranged in layers or bands are foliated.
• Examples
– Slate (from shale)
– Schist
– Gneiss (from granite)
Textures of Metamorphic Rock
• Nonfoliated rock’s grains are arranged
randomly.
• Examples:
– Marble (from limestone)
– Quartzite (from sandstone)
• Metamorphic rocks are harder and more
dense than sedimentary rocks.
Metamorphic Rock Structures
• Metamorphic rock has features that tell you
about its history.
• In metamorphic rocks, these features are
caused by deformation.
• 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.
• Folds or bends in metamorphic rock are
structures that indicate that a rock has
been deformed.
Uses of Metamorphic Rock
• Marble and slate are the two most useful
metamorphic rocks.
• Marble can be cut into thin slabs and easily
polished (Taj Mahal).
• Slate , because it is foliated, splits easily into
flat pieces.
• Slate is used for flooring, roofing, outdoor
walkways, or chalkboards.
• Marble and Slate both come in a variety of
colors.
Summary…
• There are 3 major rock groups: igneous rocks
sedimentary rocks and metamorphic rocks.
• Igneous rocks form when molten rock cools and
hardens from magma or lava.
• Sedimentary rocks form from particles
deposited, pressed, and cemented together by
water and wind.
• Metamorphic rocks form from heat and pressure,
or a chemical change.
• Forces inside Earth and at the surface produce a
rock cycle that builds, destroys, and changes the
rocks in the crust.
Quick Check
1. How does metamorphic rock form?
• A. by intense heat and pressure
• B. erosion, deposition, compaction,
cementation
• C. melting into lava or magma, then
cooling into a new rock
• D. by pressing together and then
cementation
Quick Check
2. Molten rock beneath Earth’s surface is
called
•
•
•
•
A.
B.
C.
D.
Lava.
Magma.
Sedimentary rock.
Igneous rock.
Quick Check
3. If you wanted to duplicate conditions in a
laboratory that produced metamorphic
rock from sedimentary rock, what would
you need to do?
• A. apply pressure to the rock
• B. apply high temperature to the rock
• C. apply high pressure and high
temperature to the rock
• D. let the rock stand under water for a long
time
Quick Check
4. Which of the following is a metamorphic
rock?
•
•
•
•
A.
B.
C.
D.
Granite
Sandstone
Limestone
marble
Quick Check
5. Metamorphic rocks can be formed from
•
•
•
•
A. igneous rocks.
B. sedimentary rocks.
C. metamorphic rocks.
D. all rock groups.
Quick Check
6. The rock formed when granite changes to
a metamorphic rock is
•
•
•
•
A. marble.
B. basalt.
C. gneiss.
D. pumice.
Quick Check
7. Metamorphic rocks that have their grains
arranged in parallel bands or layered are
said to be
•
•
•
•
A. jagged grained.
B. foliated.
C. nonfoliated.
D. coarse grained.
Quick Check
8. The heat that changes a rock into
metamorphic rock comes from
•
•
•
•
A. friction of plate movement.
B. the sun.
C. the heat of the mantle.
D. chemical rocks in the crust.
Quick Check
9. Geologist classify metamorphic rock
according to
• A. the exterior color of the rock.
• B. the overall shape of the rock.
• C. the arrangement of the grains that
make up the rock.
• D. the degree of hardness of the rock.
Quick Check
10. Which type of rock is MOST LIKELY to
form layers?
•
•
•
•
A.
B.
C.
D.
Sedimentary
Igneous
Metamorphic
magma
Quick Check
11. The _________ of a rock is determined
by the sizes, shapes, and positions of the
minerals the rock contains.
12. ________ metamorphic rock contains
minerals that are arranged in plains or
bands.
13. The most characteristic property of
sedimentary rock is __________.
Quick check
14. Sedimentary rock is classified into all of
the following main categories except
_________.
a. clastic sedimentary rock
b. chemical sedimentary rock
c. nonfoliated sedimentary rock
d. organic sedimentary rock
Quick Check
15. An igneous rock that cools very slowly
has a __________ texture.
a. foliated
b. fine-grained
c. nonfoliated
d. coarse-grained
Quick Check
16. Igneous rocks forms when
a. minerals crystallize from a solution.
b. sand grains are cemented together.
c. magma cools and solidifies.
d. mineral grains in a rock recrystallize.
Quick Check
17. A __________ is a common structure
found in metamorphic rock.
a. ripple mark
b. fold
c. sill
d. layer
Quick Check
18. The process in which sediment is
removed from its source and transported
is called ____________.
a. deposition.
b. erosion.
c. weathering.
d. uplift.
Quick Check
19. Mafic rocks are
a. light-colored rocks rich in calcium, iron, and
magnesium.
b. dark-colored rocks rich in aluminum,
potassium, silica, and sodium.
c. light-colored rocks rich in aluminum,
potassium, silica, and sodium.
d. dark-colored rocks rich in calcium, iron, and
magnesium.
Processes of Change
The Crust, Mantle,
and Core
Lesson 16
How do the forces within
the earth affect the
formations of the Earth’s
surface?
The Crust, Mantle, and Core
• Earth is divided into four layers: the crust,
the mantle, the outer core, and the inner
core.
• Each layer is made up of different
materials.
• It takes 6,380 kilometers to get to the
center of the Earth’s inner core.
• Each layer has a different thickness.
Thickness of Earth’s Layers
•
•
•
•
Crust: 8-32 kilometers
Mantle: 2900 kilometers
Outer Core: 2250 kilometers
Inner Core: 1300 kilometers
The Crust
• The crust is the thin outer layer of Earth.
• Earth’s crust is made of two layers.
• The top layer is made of granite; the
bottom layer is made of basalt.
• The continents are made of both granite
and basalt.
• The ocean floors are made of basalt.
The Mantle
• The makeup of the mantle’s rocks is similar to
that of the crust.
• The Moho boundary is located between the
crust and the mantle.
• Currents of the mantle’s molten rock can move
whole continents and ocean floors.
• Molten rock from the mantle burst through the
crust to create islands and volcanoes.
• The top layer of the mantle is liquid rock that we
call the asthenosphere.
The Outer and Inner Cores
• Earth’s core is made up of two parts: a
shell called the outer core and a sphere
called the inner core.
• Both cores are made up of the metals iron
and nickel.
• The outer core is liquid metal; the inner
core is solid metal.
• Tremendous pressure keeps the inner
core a solid.
Quick Check
The very top layer of Earth, found under soil
and water is which of the following:
a. upper mantle
b. crust
c. asthenosphere
d. outer core
Quick Check
Which of the following causes the
difference between the upper mantle and
lower mantle?
•
•
•
•
a. heat
b. pressure
c. erosion
D. weathering
Quick Check
The pressure on the inner core can be
compared to which of the following:
a. The same pressure as the pressure
around an exploding bomb.
b. The same pressure as the pressure of
a volcano erupting.
c. The same pressure as the pressure of
hurricane wind.
Quick Check
The inner core is made of
a. liquid metal
b. liquid rock
c. solid metal
Quick Check
The reason we have a magnetic field is due
to the:
a. gravitational pull of the sun.
b. gravitational pull of Earth.
c. movement of the inner core.
d. movement of the outer core.
Quick Check
•
From the lowest to highest temperature,
which is the correct order of Earth’s
layers?
•
•
•
•
A.
B.
C.
D.
inner core, outer core, mantle, crust
mantle, crust, outer core, inner core
crust, mantle, outer core, inner core
crust, mantle, inner core, outer core
Quick Check
• In general, how does the density of
material in Earth’s layers change with
depth?
• a. density increases with depth
• b. density decreases with depth
• c. density does not change with depth
• d. density increases, then decreases with
depth
Quick Check
In Earth’s crust, what type of rock is found
under the oceans?
a. only granite
b. only basalt
c. granite on top, basalt underneath
d. basalt on top, granite underneath
Quick Check
The thickest layer of the Earth is the
a. crust.
b. mantle.
c. outer core.
d. inner core.
Quick Check
The Moho is the boundary between the
a. inner and outer core.
b. the outer core and the mantle.
c. the crust and the mantle.
d. the crust and the atmosphere.
Quick Check
What is the composition of the core?
A: ______________________________
What is the composition of the
asthenosphere and where is it located?
A: ________________________________
_________________________________
_________________________________
Quick Check
Compare the temperature of Earth’s four (4)
layers.
Crust ______________________________
Mantle _____________________________
Outer Core _________________________
Inner Core __________________________
Quick Check
Inside the Earth, What increases with
depth?
A: ______________________________
_______________________________
_______________________________
EQ:
How does
weathering
occur?
Weathering
• Describe three ways
abrasion occurs in nature.
• List three things that
cause chemical
weathering of rocks.
• Describe the similarity in
the ways tree roots and
ice mechanically weather
rock.
• Describe five (5) sources
of chemical weathering.
Weathering
• Weathering is the process by which rock
materials are broken down by the action of
physical or chemical processes.
• Mechanical weathering is the breakdown of rock
into smaller pieces by physical means. (ice,
wind, water, gravity, plants, animals)
• Chemical weathering is the process by which
rocks break down as a result of chemical
reactions. Water, weak acids, and air can cause
chemical weathering.
6 Agents of Mechanical Weathering
• 1. Ice – water seeps into cracks during
warm weather. When the temperature
drops, the water freezes and expands,
causing the ice to push against the sides
of the crack. This causes the crack in the
rock to widen.
– Abrasion – the grinding and wearing away of
rock surfaces through mechanical action of
other rock or sand pebbles.
– The three ways that can cause abrasion are
wind, water, and gravity.
Three Causes of Abrasion
• 2. Water – as rocks and pebbles roll along
the bottom of flowing water, they bump and
scrape against each other, causing these
rocks to become rounded and smooth.
• 3. Wind – wind blows sand and silt against
exposed rock eventually wearing away the
rock’s surface.
• 4. Gravity – rocks grind against each other
during a rock slide, creating smaller and
smaller rock fragments. Anytime one rock
hits another rock, abrasion takes place.
Plants and Animals
• Some plants (#6) can easily break rocks. The
roots grow through existing cracks in rocks.
• The growth causes the root to expand, forcing
the crack to widen. The force can eventually
split the rock apart.
• 7. Animals that live in the soil (moles, prairie
dogs, insects, worms, gophers), cause a lot of
weathering. By burrowing in the ground, these
living creatures brake up soil and loosen rocks
to be exposed to further weathering.
5 Agents of Chemical Weathering
• Common agents of chemical weathering are
water, acids, and air.
• These agents weaken the bonds between
minerals grains of the rock.
• 1. Water – can cause rock to be broken down
and dissolve. Can take thousands of years to
take place.
• 2. Air – the process of oxidation is a chemical
reaction in which an element (iron) combines
with oxygen, causing rust.
– (Weak Acids) - acid precipitation, acids in
groundwater, acids in living things.
Three Sources of Weak Acids
• 3. Acid Precipitation – rain, sleet, or snow
that contains a high concentration of acid.
Normal precipitation is acidic, acid
precipitation contains more acid than normal.
• 4. Acids in Groundwater – carbonic acid or
sulfuric acid reacts with rocks in the ground,
causing a chemical reaction, eating away at
the rock.
• 5. Acids in Living Things – Lichens produce
acids that slowly break down rock.
Summary
• Ice wedging is a form of mechanical
weathering in which water seeps into rock
cracks and then freezes and expands.
• Wind, water, and gravity cause
mechanical weathering by abrasion.
• Animals and plants cause mechanical
weathering by turning the soil and
breaking apart rocks.
• Water, acids, and air chemically weather
rock by weakening the bonds between
mineral grains of the rock.
Quick Check
1. Which of the following things cannot
cause mechanical weathering?
•
•
•
•
A. water
B. acid
C. wind
D. animals
Quick Check
2. Which of the following is a type of frost
action?
•
•
•
•
A. abrasion
B. oxidation
C. ice wedging
D. gravity
Quick Check
3. Which of the following types of chemical
weathering causes a karst landscape,
such as a cavern?
•
•
•
•
A. lichens
B. acid precipitation
C. acids in groundwater
D. water
Quick Check
4. How do lichens slowly break down a
rock?
•
•
•
•
A. by abrasion
B. by mechanical means
C. by ice wedging
D. by chemical means
Quick Check
5. Which of the following will most likely
experience oxidation?
•
•
•
•
A. tennis ball
B. aluminum can
C. wooden fence
D. Bicycle tire
Quick Check
1. The grinding and wearing away of rock
surfaces through the mechanical action
of other rock or sand particles
2. Rain, sleet, or snow that contains a high
concentration of acids
3. The process by which rocks break down
as a result of chemical reactions
4. The breakdown of rock into smaller
pieces by physical means
5. A chemical reaction in which an element,
such as iron, combines with oxygen to
form an oxide
6. The process by which rock materials are
broken down by the action of physical or
chemical processes
a. mechanical
weathering
b. oxidation
c. weathering
d. acid
precipitation
e. abrasion
f. chemical
weathering
Rates of Weathering
• What is differential
weathering?
• How does surface
area affect the rate of
weathering?
• How does climate
affect the rate of
weathering?
• Why do mountaintops
weather faster than
rocks at sea level?
Differential Weathering
• Differential weathering is a process by
which softer, less weather resistant rocks
wear away and leave harder, more
weather resistant rocks behind.
• Hard rocks weather more slowly than
softer rocks.
The Shape of Rocks
• Weathering takes place on the outer surface of
rocks.
• The more surface area exposed to weathering,
the faster the rock will be worn down.
• As the surface area increases, the rate of
weathering also increases.
• If a large rock is broken into smaller pieces,
weathering of the rock happens much faster.
• The rate of weathering increases because a
smaller rock has more surface area to volume
than a larger rock.
• More of the smaller rock is exposed to the
weathering process.
Weathering and Climate
• The rate of chemical weathering is faster in
warm, humid climates than cold, dry
climates because of oxidation.
• Oxidation happens when the temperature
is higher and when water is present.
• Water increases the rate of mechanical
(physical) weathering (ice wedging).
• Repeated changes in temperature (freeze,
thaw, freeze, thaw) is a major factor in
mechanical weathering.
Weathering and Elevation
• Mountaintops weather faster than rocks at sea
level because they are exposed to more wind,
rain, and ice than rocks at sea level or lower
elevations.
• The increase in wind, rain, and ice increases the
effects of mechanical and chemical weathering.
This increase in elevation causes peaks of
mountains to weather faster.
• Gravity affects the rate of weathering:
–
–
–
–
–
Steepness
Rainwater
Removal of sediment exposes new rock to weathering
Abrasion
Increased surface area of mountain
Summary
• Hard rocks weather more slowly than
softer rocks.
• The more surface area of a rock that is
exposed to weathering, the faster the rock
will be worn down.
• Chemical weathering occurs faster in
warm, humid climates.
• Weathering occurs faster at high
elevations because of an increase in ice,
rain, and wind.
Quick Check
• A process by which softer, less weatherresistant rocks wear away and leave
harder, more weather-resistant rocks
behind is called
•
•
•
•
A. differential weathering
B. mechanical weathering
C. chemical weathering
D. ice wedging
Quick Check
• Which of the following statements describe a
rock change after it is in a riverbed for a long
period of time?
• A. The rock rapidly breaks into smaller pieces.
• B. Chunks of the rock break off, and the rock
becomes rougher.
• C. The edges of the rock are worn away, so its
surface becomes smoother.
• D. The rock absorbs water from the riverbed and
becomes softer.
Quick Check
• Small rocks weather more quickly than
larger rocks because their surface area is
•
•
•
•
A. thinner.
B. larger.
C. smaller.
D. thicker.
Quick Check
The average weather condition in an area
over a long period of time is called
A. temperature.
B. climate.
C. weather.
D. humidity.
Quick Check
• Chemical weathering is most rapid in
areas that are
•
•
•
•
A. hot and dry.
B. warm and wet.
C. cold and dry.
D. cool and wet.
Quick Check
• Which rocks are exposed to more wind,
rain, and ice?
•
•
•
•
A. rocks at a lower elevation
B. rocks at a higher elevation
C. rocks in streams
D. rocks in warm, humid climate
From Bedrock to Soil
• What is soil (loam)
formed from?
• What is bedrock?
• What is soil structure?
• What is humus?
• What are soil horizons?
The Source of Soil
• Soil is a loose mixture of small mineral
fragments, organic matter, water, and air
that can support the growth of vegetation.
• Bedrock is the layer of rock beneath soil.
• Parent rock is the rock formation that is
the source of soil.
• Wind, water, and movements of glaciers
can transport or move soil from one place
to another.
Soil Properties
• Soil is made from different-sized materials.
• Soil texture is the soil quality is based on
the proportions of soil particles.
• Soil texture can influence the ability of
water move through the soil.
• Soil structure is the arrangement of soil
particles.
Soil Properties
• Some soils are rich in nutrients, some are
poor in nutrients.
• A soil’s ability to hold nutrients and to
supply nutrients to a plant is describe as
soil fertility.
• Humus is the dark, organic material
formed in soil from the decayed remains of
plants and animals.
Soil Horizons
• Soil horizons are the horizontal
layers of soil.
• The top layer of soil is called
topsoil, containing more humus
than the other layers of soil, rich in
nutrients plants need to be healthy.
• Good topsoil is necessary for
farming.
Summary
• Soil (loam) is formed from the weathering
of bedrock.
• Soil texture affects how soil can be worked
for farming and how well water passes
through it.
• The ability of soil to provide nutrients so
that plants can survive and grow is called
soil fertility.
Quick Check
• Soil quality based on the relative size of
soil particles is called
•
•
•
•
A. residual soil.
B. soil structure.
C. soil texture.
D. soil particles.
Quick Check
• What is the arrangement of soil particles
called?
•
•
•
•
A. soil structure
B. soil texture
C. soil particles
D. infiltration
Quick Check
• What is the organic material formed in soil
from the decayed remains of plants and
animals called?
•
•
•
•
A. bedrock
B. parent rock
C. residual soil
D. humus
Quick Check
• Soil is important because it provides
•
•
•
•
A. housing for animals
B. Nutrients for plants
C. storage for water
D. All of the above
Quick Check
• Naomi made the pie graph during a laboratory
experiment in which she analyzed the
composition of loam (soil) found in Georgia.
Based on this chart, which of the following is a
valid conclusion?
• A. Approximately 95% of the material that makes up
loam is useless to plants.
• B. Decayed organic matter is the least abundant
component of loam.
• C. Only about 90% of loam’s composition is useful
to plants.
• D. Only about 16% of loam’s composition is useful
to plants.
Soil Conservation
• Why is soil important?
• How can human
activity affect soil
erosion?
• What are three
important benefits
that soil provides?
• List five methods of
soil conservation.
Soil Conservation
• Soil can be endangered, just like plants
and animals.
• It takes thousands of years for soil to form,
it is not easy to replace.
• Soil conservation is a method to maintain
the fertility of the soil by protecting the soil
from erosion and nutrient loss.
The Importance of Soil
• Soil provides minerals and other nutrients
for plant life.
• All animals get their energy from plants.
• Soil also provides a place for animals to
live.
• The region a plant or animal lives is called
a habitat.
• Soil holds water for plants to get the
moisture or nutrients they need.
The Processes of Change
Lesson 18
Processes of Change (5)
• Weathering and erosion wear down,
deposition fills in Earth’s surface.
• Weathering is the slow wearing away or
breaking down of objects exposed to
Earth’s atmosphere
• Two kinds of weathering act on Earth’s
surface
– Mechanical weathering
– Chemical weathering
Mechanical Weathering (4)
• When objects are broken down into small
pieces but their chemical makeup doesn’t
change
• Wind and moving water are two main
causes of mechanical weathering
• Repeated changes in temperature (freeze,
melt, freeze, melt again)
Chemical Weathering (5)
• Material of an object is changed
• Produces underground caverns
• Statue of Liberty needed repairs because
of chemical weathering
• Examples:
– Rust
– Acid rain
Erosion (5)
• The natural moving of material from one
place to another
• Erosion transports weathered rock
material
• Causes of Erosion:
– Moving water
– Gravity
– Wind
– Glaciers (moving rivers of ice)
– Waves
Deposition (5)
• Land torn down in one place is “deposited”
in another place
• Gravity can cause a landslide moving
mud, rock and soil down a hill
• Wind erosion can move sand and deposit
it in another area
• Glaciers (rivers of ice) scrape rocks off the
land and moves them downhill
Deposition (5)
• Glaciers will stop moving and even retreat and
cut a steep U-shaped valley in the land
• Erosion caused by mountain rivers form Vshaped valleys
• Hurricanes create waves that erode beaches
and cliffs
• Breaking of waves on a beach can wear it away.
The larger the waves, the faster is the rate of
erosion.
Quick Check
Which of the following processes was
responsible for producing the Grand
Canyon?
A. only weathering
B. only erosion
C. weathering and erosion
D. Movement of a glacier
Quick Check
The wearing away of the ancient Egypt’s
Great Sphinx is an example of
A. weathering
B. mechanical weathering
C. erosion
D. deposition
Quick Check
A landslide is an example of erosion caused
by
A. wind
B. running water
C. the movement of a glacier
D. gravity
Quick Check
What causes a sand dune to move from one
place to another?
A. wind
B. waves
C. tides
D. running water
Quick Check
About how many years does it take to
change flat land into a very deep canyon
like the Grand Canyon in Arizona?
A. tens of years
B. hundreds of years
C. thousands of years
D. millions of years
Lithospheric Plates
EQ:
How do the
lithospheric plates
affect Earth’s
surface?
Lesson 19
Lithospheric Plates
• What features of Earth
are produced by the
movement of lithospheric
plates?
• What was Alfred
Wegener’s hypothesis?
• What is a scientific
hypothesis?
• What does the collision of
two continental plates
produce?
Lithospheric Plates (8)
• Earth's surface is like a jigsaw puzzle in motion
• The pieces in the puzzle are made of large
chunks of Earth’s lithosphere
• Lithosphere is the solid outer layer of Earth
• It includes the crust and the top of the mantle
• The moving chunks of the lithosphere are called
lithospheric plates
• Continents and the ocean floor rest on these
plates
• Where these plates collide or separate, events
take place that shape Earth’s surface
Continents in Motion (6)
• German scientist, Alfred Wegener, hypothesized
that all land masses on Earth had once made up
a single, giant continent.
• A hypothesis is a proposed explanation for one
or more observations.
• As millions of years passed, pieces of this giant
continent separated and moved to their present
positions
• This process is called continental drift
• Continents move about 2 cm a year
Fossils (7)
• Fossils can show evidence of continental drift
• For example, mesosaurus was a reptile that
lived more than 250 million years ago
• It lived in freshwater lakes and rivers
• Scientists found its fossils in both South America
and Africa
• These continents are now separated by the salty
Atlantic Ocean
• How did their remains end up on both
continents?
Events Caused by Moving Plates (5)
• Scientists divide Earth’s lithospheric plates
into two groups– Less dense continental plates
– More dense oceanic plates
The collision of these plates produce different
events on Earth’s surface
Oceanic Plate vs. Continental Plate
(3)
• When an oceanic plate runs into a
continental plate, the more dense plate
slides under the less dense plate
• This causes volcanic mountains like Mount
St. Helens in the state of Washington to
form.
Oceanic Plate vs. Oceanic Plate (4)
• When two oceanic plates meet, one slides
under the other
• A deep trench in the ocean floor forms and
volcanic islands may pop through the
ocean’s surface.
• The Aleutian islands between Alaska and
Russia were formed this way
Continental Plate vs. Continental Plate (5)
• When two continental plates collide,
neither slides under the other
• The plates buckle upward where they
meet
• This buckling produces mountain
ranges
• Example: the Himalayas in Asia
Earthquakes! (5)
• Some plates get stuck as they push into
each other or slide past each other.
• When they become unstuck, a sudden jolt
happens.
• Energy is released and energy sends
waves through the ground.
• This causes the ground to shake…It’s an
earthquake!
Earthquakes Part 2 (5)
• Earthquakes occur more frequently along
plate boundaries than anywhere else.
• This accounts for the “Ring of Fire” that
curves around the Pacific Ocean.
• The “Ring of Fire” is a belt where
volcanoes and earthquakes are very
common.
• The belt follows the borders of plate
boundaries.
Quick Check
• What features of Earth are produced by
the movement of lithosphere plates?
A. solid masses of iron and nickel
B. liquid masses of iron and nickel
C. red-hot magma
D. mountains ranges, volcanoes, and volcanic
islands
Quick Check
What was Alfred Wegener’s hypothesis?
A. The continents have always been where they
are now.
B. Today’s continents were once part of a single
land mass that split apart.
C. The continents are made of rock.
D. The continents will one day join to form a
single continent.
Quick Check
Earthquakes are MOST LIKELY to occur at
the borders of
A. continents.
B. lithospheric plates.
C. countries.
D. oceans
Quick Check
• A scientific hypothesis is
– A. a fact.
– B. an explanation that has been supported by
repeated observations and experiments.
– C. a proposed explanation for one or more
observations.
– D. a guess that is not based on observations.
Quick Check
• The collision of two continental plates can
produce
– A. volcanic islands.
– B. a mountain range.
– C. a single mountain
– D. a trench.
EQ: How has the physical
process of plate tectonics
effected Earth’s surface?
Lesson 20
Effects of Physical Processes
• Just as there was once a single great land
mass, there was also a single great ocean
around that land mass.
• The separate oceans we now know were
formed as the land masses separated.
• These separations produced amazing
features on the ocean floor, such as the
longest mountain range on Earth.
Plate Tectonics Part 1
• Many physical processes have shaped
Earth’s surface.
• The physical process of plate tectonics
have shaped Earth’s oceans.
• Plate Tectonics describes how Earth’s
lithospheric plates move and how their
movements shape Earth’s crust.
• The continents and ocean floor of Earth
ride on 13 lithospheric plates
Plate Tectonics, 2
• In the 1950s, scientists discovered that rocks on
the floor of the oceans were younger than rocks
on the continents.
• Harry Hess, an American geologist, suggested
that the sea floor was spreading.
• As it spread, from an opening in its middle,
magma from Earth’s mantle oozed from the
opening onto the surface of the ocean floor.
• When the magma came in contact with
seawater, it hardened into new rock.
Plate Tectonics
• This rock formed a huge mountain range that
snakes through all of Earth’s oceans.
• This undersea mountain range is called the
midocean ridge.
• As distance from the opening increased, the age
of the rocks also increased.
• Because the spreading has been constant
throughout history, the formation of the South
Atlantic Ocean can be traced back to a time
when South America and Africa were once part
of the same landmass.
Convection Currents, 1
• Lithospheric plates move due to convection
currents in Earth’s mantle.
• A convection current is a current formed by
heated liquid that moves along a circular path.
• Warm liquid moves upward and across a surface
because it is less dense.
• It cools at the surface, becomes more dense,
and moves downward.
• Then it warms again, becomes less dense, and
moves upward.
Convention Currents, 2
• As long as heat is applied from below, the liquid
will move around and around in convection
currents
• Heat from Earth’s mantle sets up convection
currents.
• These convection currents are made up of liquid
rock.
• The liquid rock rises to a place under the
lithospheric plates.
• The currents move in opposite directions,
pushing plates apart in one place, and together
in another place.
Quick Check
Plate tectonics describe movements
MAINLY in
– A. Earth’s crust.
– B. Earth’s mantle.
– C. Earth’s outer core.
– D. Earth’s inner core.
Quick Check
• Which ocean was produced by seafloor
spreading between Africa and South
America?
– A. Pacific Ocean
– B. Indian Ocean
– C. North Atlantic Ocean
– D. South Atlantic Ocean
Quick Check
• As distance increases from a mid-ocean
ridge, the rocks
–A. grow younger
–B. grow older.
–C. do not change in age.
–D. become liquid.
Quick Check
• Assume a sea floor has been separating
at an average rate of 5 cm a year. The
sea is presently 8000 km wide. How long
ago did the sea begin to form?
•
•
•
•
A. 1,600 years ago
B. 40,000 years ago
C. 160,000,000 years ago
D. 4,000,000,000 years ago
Quick Check
• A convection current of magma is made
up of
– A. a rising more dense liquid and a sinking
less dense liquid.
– B. a rising less dense liquid and a sinking
more dense liquid.
– C. liquids of the same density.
– D. solids of different densities.
EQ: How do fossils show
evidence of the changing
surface and climate of the
earth?
Lesson 21
Fossils
• A fossil is the remains or evidence of a onceliving thing.
• Most fossils are found in sedimentary rocks.
• Fossils can reveal what an area on Earth looked
like millions of years ago.
• They also can help us understand the type of
climate that area experienced millions of years
ago.
• The upper layers of rock are younger than the
lower layers of rock.
Changing Climates
• Scientists have found evidence of fossils
of corals in Arctic waters.
• Corals can live only in warm water.
• The fossils indicate that a long time ago
the Arctic was a warm place.
• Scientists found fossils of alligators in
Canada.
• Alligators live in warm swampy areas.
• Conclusion is that Canada was once warm
and swampy.
Changing Surfaces
• Fossils also provide clues to how Earth’s surface
may have changed over thousands and millions
of years.
• Scientists have found seashells high in the
foothills of the Andes Mountains.
• Two hypotheses:
• - Either, the sea once rose to cover the hills
• - Or, the hills rose from under the sea.
• Regardless of which hypothesis is correct, we
know that the surface of this part of the world has
changed over time.
Quick Check
What can fossils reveal about Earth’s past?
A. Only changes in Earth’s climate over
time
B. Only changes in Earth’s surface
features over time
C. Changes in Earth’s climates and
surface features over time
D. Present climates and surface features
of Earth
Quick Check
A seashell on top of a hill MOST
LIKELY indicates that
A. The hill was once under the sea.
B. Sea animals once lived on land.
C. Seashells are not parts of living
things.
D. All hills were once under water.
Quick Check
What can fossils reveal about Earth’s past?
A. Only changes in Earth’s climate over
time
B. Only changes in Earth’s surface
features over time
C. Changes in Earth’s climates and surface
features over time
D. Present climates and surface features of
Earth
Quick Check
Finding a fossil of a palm tree in Alaska
could be explained if the climate of
Alaska
A. was once colder than it is now.
B. has always been the same as it is
now.
C. was once warmer than it is now.
D. is warming up now.
Quick Check
If you found a fossil of a freshwater
animal in a desert, what could you
conclude?
A. The ocean once covered the
desert.
B. The desert rose from the sea.
C. The desert sank beneath the
ocean.
D. A river once flowed through the
desert.
Quick Check
• The fossil of a tiny horse is found in a layer of
rock below the fossil of a larger horse. What can
you conclude?
• A. The tiny horse fossil is younger than the
larger horse fossil.
• B. The tiny horse fossil and the larger horse
fossil are the same age.
• C. The tiny horse fossil is older than the larger
horse fossil.
• D. The larger horse fossil is older than the tiny
horse fossil.
EQ: What is the
composition of soil?
Lesson 22
The Composition of Soil
• Soil is a combination of :
– Weathered rock
– Decayed parts of plants
– Decayed parts of animals
– Water
– Air
• It takes thousands of years to form.
• Without soil, life on Earth as we know it
would not be possible.
Formation of Soil, 1
• Begins when exposed rock starts to
weather
• Wind, moving water, and changes in
temperature break rock into tiny pieces
• Organisms like bacteria and fungi begin to
grow in the young soil
• These organisms produce acids that
further break down particles of rock
• This process produces minerals and the
nutrients plants need for growth
Formation of Soil, 2
• Soon small plants take hold in the
new soil with their roots.
• Plants grow and die, along with
animals, and soil bacteria and fungi
break these organic materials down
• Organic material is a substance that
was originally part of a living thing
A Soil Profile, 1
• Soil that has developed over thousands of
years is called mature soil.
• A soil profile is made up of three layers
called horizons.
A Soil Profile, 2
• The top horizon, or A horizon, is very rich in
nutrients. It is called topsoil.
• The middle layer, or B horizon, is known as
subsoil. This is where you find clay and
minerals washed down by water
seeping through the A horizon
(topsoil)
Deep roots reach into the subsoil.
The last horizon, C, you will find solid bedrock
Quick Check
What is the last stage in the production of
soil?
A. Fungi and bacteria produce acids that
break down rock
B. Exposed rock weathers
C. Plants begin to grow in the ground
D. Fungi and bacteria break down organic
material
Quick Check
Soil is made up of
A. only weathered rock
B. only organic material
C. weathered rock and organic
matter
D. only animals and plants
Quick Check
What process is MAINLY responsible for
producing minerals and nutrients in very
young soil?
A. decay of animals and plants
B. production of acids by bacteria and
fungi
C. growth of plants
D. weathering
Quick Check
From top to bottom, what are the horizons
of soil?
A.
B.
C.
D.
Bedrock, subsoil, topsoil
Subsoil, bedrock, topsoil
Topsoil, subsoil, bedrock
Topsoil, bedrock, subsoil
Quick Check
Which of the following contains
organic material?
A. grass
B. unweathered rock
C. water
D. air
EQ: How do humans add
to the erosion process?
Human Activity and Erosion
Natural agents of erosion:
– Wind
– Moving water
– Gravity (landslides)
– Waves
– Glaciers (rivers of ice)
Humans add to the erosion process:
– Logging
– Mining
– Farming
– Construction
Logging
• People use trees to build homes, make
furniture and paper.
• In a method called clear-cutting, all the
trees in an area are cut down.
• Roots that used to hold the soil in place
die and decay.
• Rain washes the soil away.
• Soil has been robbed of nutrients and
minerals needed for plants to grow.
Mining
• To get minerals from the ground, miners
strip away the surface of the land.
• Strip-mining and open-pit mining remove
plants from an area.
• Plants prevent soil erosion by flowing
waters and wind.
• Without plants, erosion speeds up.
• Thousands of years may pass before
enough topsoil builds up to support plant
life.
Farming
• Planting crops can benefit many people.
• Planting crops and an unexpected natural event
can produce a disaster.
• From 1930 to 1937, a drought struck the midwestern part of the U.S.
• Grasses could have protected the soil during the
drought.
• Winds picked up the topsoil and blew it 100s of
miles eastward.
• This event is known as the “Dust Bowl.”
Construction
• Building of roads, buildings, and
communities removes natural barriers,
such as plants, to erosion.
• Erosion speeds up and the land becomes
barren and ugly.
• Today, city officials consider erosion when
they plan new construction plans.
Quick Check
• What is MAINLY responsible for
preventing erosion?
A.
B.
C.
D.
mining
farming
rooting of plants
logging
Quick Check
• Which human activity is related to logging?
A.
B.
C.
D.
strip mining
clear-cutting
drought
open-pit mining
Quick Check
• A landslide is an example of
A.
B.
C.
D.
erosion
a mining process
A logging process
A farming process
Quick Check
In what part of the United States was the
“Dust Bowl” located?
•
•
•
•
A.
B.
C.
D.
northern
eastern
western
central
Quick Check
What was the MAIN cause of the “Dust
Bowl”?
A. floods
B. Storms
C. wind
D. drought
EQ: What are some ways
that humans can conserve
natural resources?
Conserving Natural Resources
• Vital resources in danger:
– Soil has become unfit for growing crops
– Water unhealthy to drink, cook with, wash in
– Air has become polluted with substances
Natural resources can be kept healthy in two
ways:
– Conserved - saved before it turns bad
– Reclaimed - made healthy again after it
has turned bad
Soil Conservation
• Methods used to keep topsoil from being
swept away by flowing water and wind.
• Rolls of trees, called windbreaks, are
planted along the edge of farmland to
block winds.
• In terracing, farmers cut level areas into
the sides of mountains to block or slow
down the downward rushing water.
Soil Conservation
• To make land healthy again, people
can plant grasses that can live
through a drought.
• Grasses will die and decay and add
nutrients to the soil.
• The roots of the living grasses hold
the soil in place.
Water Conservation
• The main threats to our supply of healthy water
are pollution and waste.
• To conserve water:
– Replace old showerheads and faucets with
water saving showerheads and faucets
– Replace old toilets with water-saving toilets
that uses less water per flush
– Turn off the faucet while you brush your teeth.
– Turn on the dishwasher only when you have a
full load of dishes.
Water Conservation
• Water pollution comes from different
sources:
– Sewage treatment plants should not pour
untreated sewage into bodies of water.
– Factories and mines must be prevented from
dumping harmful chemicals into bodies of
water.
– Methods must be used to prevent fertilizers
from washing off of farmlands into bodies of
water.
Air Conservation
• Air is made up of 78% nitrogen, 21%
oxygen, and 1% other gases.
• We need oxygen to live.
• Human activities put gases into the air that
can harm you.
• Air pollution describes air that holds
harmful gases.
• Harmful substances in air, water, or soil
are called pollutants.
Air Conservation
• Two sources of air pollutants:
– vehicles that burn gasoline or oil
– Industries whose smokestacks pour
chemicals and bits of dirt into the air
Passed laws to protect air from pollution.
Put filters on smokestacks.
Air Conservation
Laws require car manufactures to put in
exhaust systems.
State laws require the use of fuels in
vehicles that lessen the amounts of
pollutants that enter the air.
States require steps to reduce harmful
vehicle emissions.
Quick Check
Terracing is a method used to conserve
A.
B.
C.
D.
water.
air.
soil.
fuel.
Quick Check
A windbreak conserves
A.
B.
C.
D.
wind.
soil.
water.
air.
Quick Check
For a family of four, what indoor use of water
consumes the MOST water per day?
A.
B.
C.
D.
Washing dishes
Doing laundry
Drinking and cooking
Flushing toilets
Quick Check
What would reduce automobile air
pollution the MOST?
A.
B.
C.
D.
Putting filters on car exhaust systems
Driving fewer miles
Switching to cars that run on electricity
Driving cars that use less fuel
Quick Check
How is farming MOST LIKELY to produce
water pollution?
•
•
•
•
A. Fertilizers may enter bodies of water.
B. Foods may enter bodies of water.
C. Soil may enter bodies of water.
D. Gases may enter bodies of water.
Summary of Plate Tectonics
Quick Check
When two plates converge, one plate is usually
forced to slide under the other. Oceanic plates are
more dense than continental plates. If an oceanic
plate collides with a continental plate, what will be
the likely result?
A. The continental plate will slide under the oceanic
plate, generating an oceanic trench.
B. The oceanic plate will slide under the continental
plate, generating an oceanic trench.
C. The continental plate will slide under the oceanic
plate, generating an earthquake.
D. The oceanic plate will slide under the continental
plate, generating an earthquake.
Quick Check
If two plates meet at a convergent
boundary and do not form a subduction
zone, they may
A. fold.
B. fault.
C. weather.
D. erupt.
Quick Check
• The process of seafloor spreading
occurs at what kind of plate
boundary?
A. divergent
B. convergent
C. transform
D. at both convergent and transform
boundaries
Quick Check
Where does magma come
from?
•
•
•
•
A. the inner core
B. the outer core
C. the mantle
D. the lithosphere
Quick Check
The ancient supercontinent,
Pangea, once contained
A. all of the Earth’s tectonic plates.
B. all of Earth’s crust.
C. all of Earth’s continental crust.
D. all of Earth’s oceanic crust
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