Transcript Unit 2 Geology Powerpoint

Plate Tectonics
The Earth
• The Earth is composed of 3 different
compositional layers, the crust, mantle, and
core.
• The crust is the exterior surface that we walk
on. It is also the thinnest layer. 2 types,
continental and oceanic.
• The mantle is the middle layer between the
crust and the core. It is the thickest layer.
Rocks here are in a plastic like state.
• The core is the heart of the Earth. The core has
the highest temperature.
The Earth
• The Earth is also composed of 5 physical
layers or mechanical layers.
• These layers are called physical layers
because each layers has a different set of
physical properties.
Lithosphere
• Lithosphere: made up of the crust and the
upper rigid part of the mantle, also known
as a tectonic plate.
• A tectonic plate can be made of granitic
(land, light) or basaltic (ocean, heavy) crust.
Asthenosphere
• Plastic like layer of the mantle on which
tectonic plates (lithosphere) slide around on.
• The asthenosphere is made of solid rock but
the rock flows very slowly. It is NOT
molten, it is solid.
Mesosphere
• Mesosphere: lower part of the mantle.
• Rocks here are still solid, but flow like the
asthenosphere.
Outer Core
• Outer Core: outer layer of the core.
There are no rocks here, all have melted
(or turned to magma).
Inner Core
• Inner Core: Innermost layer, the rocks here
are formed due to extreme pressures inside
the Earth. This pressure causes the rocks to
be solid and not melt even though
temperatures are extremely high.
• The inner core is made up mainly of Iron
and Nickel which are 2 of the most dense
elements inside Earth.
Review Question
• What are Earth’s compositional layers?
• What are Earth’s mechanical layers?
• What makes these layers different from
each other? Mechanical vs compositional
Plate Tectonics
• The Earth’s outer layer (lithosphere) is
broken up into large pieces called tectonic
plates.
• These plates move around on the
asthenosphere.
• The movement of these plates cause
different major geological events to happen
such as volcanoes, earthquakes, and
tsunamis.
Boundaries between Plates
• Tectonic plates can slide past one another,
crash into each other, or pull apart from one
another.
• Evidence of the plates moving is supported
by earthquakes, volcanoes, mountain
building, and tsunamis.
Types of plate boundaries
• Strike-slip or Transform boundary: plates are
sliding past each other. Earthquakes are the result.
• Convergent: plates are colliding together.
Mountains, subduction zones, and volcanoes are
the result.
• Divergent: plates are separating or pulling apart
from each other. New sea-floor forms here midocean ridges are the result.
• The Mid-Atlantic Ridge is the driving force
behind the theory of plate tectonics.
• Subduction zone: Zone where 2 plates meet
underground. Friction here cause rock to melt.
Review Questions
• How does the Earth behave at the
following faults: transform, convergent,
divergent?
• What is a tectonic plate?
• What is the Mid-Atlantic ridge and what
is it responsible for?
• What evidence is there for the theory of
plate tectonics?
Convergent Boundaries
Oceanic - Oceanic
OceanicContinental
Continental-Continental
Evidence – Earthquakes
• Earthquakes: happen when tectonic plates are
sliding past each other (transform boundary). The
plates bind up on each other and when enough
tension between the plates is built up, they slip,
causing an earthquake.
• The ground in an earthquake actually moves cause
damage to buildings, roads, etc.
• Earthquakes that happen under water can cause a
tsunami (tidal wave) to occur.
• **Measured with the Richter Scale 1-10.**
Evidence - Volcanoes
• Volcanoes: Created where plates are converging on each
other. 1 plate will slide under the other plate causing enough
friction in a localized area to cause the rock to melt. This
molten rock will burn up to the surface and create a volcano
over time. Most volcanoes are located in the Pacific Ring of
Fire because of subduction zone around the Pacific Ocean.
• Not all volcanoes are created this way. Some are created at
hot spots such as the Hawaiian Islands. A hot spot is an area
where magma has burned through the lithosphere and
created a volcano or volcanic island not at a plate boundary.
• Volcanoes can cause major problems worldwide with ash
deposits on land and ejected into the atmosphere.
Pacific Ring of fire/ Volcanoes worldwide
Cinder Cone - smallest, least destructive
Shield Volcano - largest, not very destructive
Composite (Strato) Volcano –
mid sized, most destructive
Composite volcano
Eruptions range from
Simple lave flows to
Major eruptions.
Mt. Rainier, Washington
Hydrothermal Vents
• Also called geysers or black smokers.
• Vents: opening where magma can flow onto
Earth’s surface, typically found at divergent
boundaries.
• A hydrothermal vent is an area where water
is in contact with magma below the surface
of the earth. These vents can be found on
land and under water.
• Examples, Old Faithful at Yellowstone and
black smokers on the ocean floor.
Hydrothermal vents
Black smokers
Erupts every 35-120
Minutes. In Yellowstone
National Park, Wyoming
Review Questions
• Why are volcanoes evidence of plate
tectonics?
• Why are earthquakes evidence of plate
tectonics?
• What problems can earthquakes and
volcanoes cause?
• What is a hydrothermal vent? Where
are they located? Why are they evidence
of plate tectonics?
Conclusion
• The Earth is made up of compositional layers,
crust, mantle, and core. The physical layers are
known as the lithosphere, asthenosphere,
mesosphere, outer core, and inner core.
• The Earth’s surface is broken into plates called
tectonic plates. These plates move around on the
asthenosphere causing major geologic events such
as mountain building, earthquakes, tsunamis, and
volcanoes.
Conclusion
• The plates can have different boundaries such
as transform, convergent, and divergent.
• The Mid-Atlantic ridge is the driving force for
the theory of Plate Tectonics.
• Hot spots are created when magma burns
through a tectonic plate (not at a boundary)
and creates a volcanic island.
• Geysers and hydrothermal vents occur on land
and under water when water comes into
contact with magma.
GPS
• S6E5. Students will investigate the scientific view of
how the earth’s surface is formed.
– b. Investigate the contribution of minerals to
rock composition.
Minerals
The Building Blocks
Minerals
• Mineral: Is a naturally
formed, inorganic
solid with a crystalline
structure
Minerals are made of elements
• Elements are made up of
• An element is a pure
atoms.
substance that cannot be
broken down into simpler • An atom is the smallest
substances by ordinary
part of an element that
chemical means
has all the properties of
that element.
• made of elements, such
as oxygen, iron, gold,
• When more than 1 type of
silver, hydrogen,
atom are chemically
aluminum, etc.
bonded together, they
make a compound.
Review
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What is a mineral?
What is an element?
What are elements made of?
What is an atom?
What is a compound?
Rocks
What are they, where
do they come from?
GPS
• S6E5. Students will investigate the scientific
view of how the earth’s surface is formed.
– a. Compare and contrast the Earth’s crust, mantle, and
core including temperature, density, and composition.
– b. Investigate the contribution of minerals to rock
composition.
– c. Classify rocks by their process of formation.
– d. Describe processes that change rocks and the surface
of the earth.
– g. Describe how fossils show evidence of the changing
surface and climate of the Earth.
What is a rock?
• Rock: solid mixture of
crystals of one or more
minerals, some rocks,
such as coal, are made of
remains of organic
material (dead plants and
animals).
• Rocks can range in size
from a grain of sand to
thousands of miles long.
The value of rock(s)
• Rock has been used in
the past to make many
objects such as
hammers, knives,
spears, statues, etc.
• Today it is used to
make buildings,
scalpels, statues,
counter tops, etc.
• Rocks provide a
history of what Earth
and other planets were
like before recorded
history. A rock is
much like a time
capsule.
The value of rock(s) cont’d
• Some rocks contain
fossils that help to
provide clues as to
what Earth was like
millions of years ago.
• We would know very
little about the Earth
before recorded
history without rocks
and fossils.
The rock cycle:
CC
Sediments
Sedimentary Rock
WE
WE
M
WE
Igneous Rock
M
HP
Metamorphic Rock
HP
CS
CS = Cool and solidify
WE = weathering and erosion
CC = compaction and cementation
M
Magma/
Lava
M = melting
HP
HP= heat and pressure
How do rocks melt?
• 1. Increase in Temperature: an increase can cause
rocks to melt.
• 2. Release of Pressure: causes rocks to stay a solid
deep inside the Earth. When these rocks move
towards Earth’s surface the pressure is released
and the rock melts.
• 3. Change in Composition: when water or carbon
dioxide enter a rock near its melting point, it
lowers it melting point enough to cause the rock to
melt.
How to classify rocks
• Composition: Elements
a rock is made of.
• A rock that has a
majority (60% and
above) of one mineral
will have a composition
close to that mineral
• Likewise if a rock has
no dominant mineral it
will have a unique
composition.
How to classify rocks
• Texture: determined by
the sizes, shapes, and
positions of mineral
grains of which it is made
of.
• 3 types: fine-grained,
medium-grained, and
coarse-grained.
• The longer it takes
magma to cool, the larger
the crystals (grains) grow.
• Fine-grained: extremely
small grains.
• Medium-grained: sand
sized grains.
• Coarse-grained: contains
larger grains such as
pebbles or broken pieces
of other rocks.
Review Questions
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What is a rock?
Why are fossils important?
Name the 3 ways rocks can melt.
How is composition different from
texture?
• What are the 3 main textures?
Types of rocks
• There are 3
types of rocks:
• Igneous
• sedimentary
• metamorphic
Magma
• The type of magma will determine what
type of igneous rock (felsic/mafic), that is
formed.
• This will, in time, affect the type of rock it
forms later on.
Igneous Rocks
• Magma that has
cooled and solidified.
• Two types of igneous
rocks: felsic and
mafic.
• Types of igneous
formation: intrusive
and extrusive.
Felsic Vs. Mafic
• Felsic:
• light colored, less
dense.
• Rich in elements
such as silicon,
aluminum, sodium,
and potassium.
• Ex. granite.
• Mafic
• dark colored, more
dense.
• Rich in iron,
magnesium, and
calcium.
• Ex. gabbro
Intrusive
• Intrusive: When
magma cools beneath
the Earth’s surface.
• Intrusive igneous
formations can be
found on Earth’s crust.
• Usually has a coarse
grained texture
because it has a long
time to cool.
• Examples: dike,
volcanic neck, pluton,
sill, batholith, and
laccolith.
Extrusive
• Extrusive: created
when lava cools and
solidifies on Earth’s
surface or under water.
• Most volcanic rock is
extrusive.
• Contains either small
or no crystals. (finegrained)
Igneous Rocks Review
• Is affected by a change composition,
pressure, and/or temperature.
• There are 2 types of igneous rocks, intrusive
and extrusive.
• They are further classified as mafic or
felsic, fine, coarse, or medium grained
textured, and their compositions.
Review Questions
• What is an igneous rock?
• How are felsic rocks different from mafic
rocks?
• How does magma affect igneous rocks?
• How are intrusive rocks different from
extrusive?
Sedimentary Rocks
The breakdown!!
Sedimentary Rock
• Weathering: when rocks are broken down by wind,
water, ice, sunlight, and gravity.
• Weathering creates small fragments of rock called
sediments.
• These sediments are moved around by weathering
forces.
• Eventually these sediments are deposited in layers.
Usually at the bottom of slow moving water.
• The sediments will form layers, one on top of another.
After time and pressure, the layers will be compacted
and cemented. This forms a sedimentary rock. These
lines are called strata.
Classification of Sedimentary
Rocks
• 3 main types:
– clastic
– chemical
– organic
Their grain size also helps to classify the rock:
fine, medium, and coarse-grained.
Clastic
• Clastic: Made from
fragments of other
rocks and minerals
• this is a coarsegrained,
conglomerate.
(made up of other
pieces of rock.
• Fragment size helps
determine clastic
rock name.
Chemical
• Chemical: Forms from
solutions of minerals
and water.
• Usually as water
evaporates, the
minerals are left
behind and solidify
and form a chemical
sedimentary rock.
Organic
• Organic: Rock that forms from the remains of
once living organisms.
• Fossils are classified as organic sedimentary
rocks.
• Fossils are the remains of once living organisms
that have solidified to form rock.
• Most fossils are found where water once was or is.
Review Questions
• What is a sedimentary rock?
• What are the 3 main types?
• How do the 3 types of sedimentary rocks
form?
• What type of sedimentary rock is a
fossil?
Metamorphic
Rock
• Metamorphic rock:
Rocks whose structure,
texture, or composition
have been changed.
• All types of rocks can
become a metamorphic
rock - igneous,
sedimentary, and
metamorphic.
Where do they come from?
• If the temperature or pressure of a rocks new
environment changes from the one it formed it,
the rock will undergo metamorphism.
• Most metamorphic rocks are created from an
increase in pressure deep inside the Earth.
• Temperatures as low as 50 degrees Celsius and
as high as 1000 degrees Celsius can cause rocks
to metamorphose. Temperatures hotter than that
melt a majority of rocks.
Contact versus regional
metamorphism
• Contact metamorphism:
happens when rocks
come into contact or are
close enough to magma
to alter the rocks
composition.
• Only happens at igneous
intrusions.
• Rocks are “cooked”
• Regional metamorphism:
happens when rocks
pressure builds up on a
rock or when Earth’s
crust collides together at
fault boundaries.
• Rocks can undergo both
regional and contact
metamorphism.
Metamorphic rock composition
• Composition changes after metamorphosis
due to the heat and pressure.
• Some metamorphic rock compositions can
be only created at certain temperatures and
pressures.
Metamorphic rock textures
• Foliated: mineral
grains are aligned,
some look like pages
in a book, while others
do not.
• Example: gneiss, and
schist.
• Nonfoliated:
metamorphic rock that
does not contain
aligned mineral grains.
The grains seem to
grouped together
instead of organized
into layers.
• Examples: marble and
quartzite.
Review:
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Rock is a solid mixture of crystals or one or more minerals.
3 types of rock: igneous, sedimentary, and metamorphic.
Rocks go through a cycle called the rock cycle.
Igneous rocks are formed from cooled magma or lava.
– types: intrusive and extrusive
• sedimentary rocks are formed from remains of other rocks
and sometimes organic material.
– Types: clastic, chemical,and organic
• Metamorphic rocks are created when rocks undergo a
change.
– Types: foliated and nonfoliated.
Review Questions
• What is a metamorphic rock?
• What are the 2 main types of
metamorphic rocks?
• How are the 2 types different from each
other?
• How is regional metamorphism different
from contact metamorphism?
Chapter 5
Energy Resources
Natural Resources
• Any natural material
that is used by humans.
• Examples: water,
petroleum, minerals,
wind, sunlight, wood,
nuclear and animals.
• Most have to be
changed or altered for
human use.
Renewable Resources
• Renewable resource: A
resource that can be
replaced at a close rate to
how fast it is used.
• Example: trees, can be
replaced in as little as 15
years.
• Examples: wood, biomass
(trash), geothermal, solar,
wind, hydroelectric,
nuclear, hydrogen, and
Nonrenewable Resources
• Nonrenewable resource:
Resource that is used at a
much faster rate at which is
can be replaced.
• Example: petroleum (used
to make gas), takes millions
years to form.
• Examples: petroleum, coal,
and natural gas (fossil fuels)
• The U.S. gets about 85% of
its energy from fossil fuels.
Fossil Fuels
• Fossil Fuels: created from organisms that lived
long ago…from a few thousand to several million
of years. Tremendous amounts of pressure from
layers of earth turns these organisms into fossil
fuels.
• We obtain these fuels from pumping them out of
of the ground or by digging them by using mines
(deep or shallow).
• To get the energy from fossil fuels, we typically
burn them.
Problems with Fossil Fuels
• When fossil fuels burn, they release
compounds into the atmosphere that can
combine with water to create smog, ozone,
or acid precipitation.
• These by-products can harm or even kill
animals, plants, and humans. Many
respiratory diseases such as asthma are
caused by these pollutants.
Alternative Resources
• Alternative resources: Another form of
energy used that does not pollute the Earth’s
atmosphere like fossil fuels do.
• Examples: nuclear (fusion and fission),
chemical energy, solar energy, wind power,
hydroelectric, gasohol (gas + alcohol),
geothermal, methane, etc.
Inexhaustible Resources
• Inexhaustible resources: Energy forms such
as nuclear, hydroelectric, solar, wind, and
geothermal are considered inexhaustible
resources because they would never run out
(at least for the next 5 billion years or so).
Types of Energy: what / where they
come from
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Hydroelectric: water
Solar: sun
Geothermal: Earth (heat from inside)
Nuclear: energy from atom (splitting (fusion) or forcing
them together (fission)).
Wind: wind (ultimately the sun)
Petroleum: dead plants & animals (organic)
Biomass: dead plants, animals, & animal waste
Chemical: reacting chemicals create energy
Natural gas: organic matter (dead plants and animals).
Conclusion
• We use many different types of energy
sources on Earth, most have to altered to be
an effective form of energy while others do
not.
• Some pollute the Earth’s atmosphere (fossil
fuels) while others do not (wind, solar, etc)
• Some resources (fossil fuels) will run out,
others renewable and inexhaustible
resources will never run out.
Review Questions
• What are natural resources?
• How are renewable different from
nonrenewable?
• What are fossil fuels?
• What are some problems with fossil
fuels?
• What are some alternative resources?
• What are inexhaustible resources?