Unit 3 STUDY GUIDE – Earth’s Resources
Earth’s Resources
Layers of the Earth
The structure of the earth is divided into four major components: the crust, the mantle, the outer core, and the inner core.
Crust:
The crust is the thinnest of all the layers. This layer is where all life is
found.
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2 types of crust:
o oceanic crust is the top layer that is found on the
ocean floor: thinner, colder and more dense than
continental crust
o continental crust is the top layer that lies under
the continents we all live on: thicker and less
dense than oceanic crust
Mantle:
The mantle is much thicker than the crust and is made up of different
minerals.
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makes up 85% of the Earth’s weight
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this layer is made of magma (very hot semi-solid rock)
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has two layers: upper mantle and lower mantle
o Upper mantle has two layers
 Lithosphere (lower part) that is
just below the crust. Is solid rock and
about 50 to 120 km thick
 Asthenosphere - the bottom part of the
upper mantle. Less solid, more plastic
than the region above it.
About 350 km thick
Outer Core:
This layer is extremely hot and is in a liquid state.
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swirling layer of molten Ni (Nickel) and Fe (Iron).
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outer core creates a magnetic field that reaches into
outer space
o this magnetic field protects the Earth from the
damaging solar winds that come from the sun
Inner Core:
This final layer is at the very center of the Earth
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this layer is under very high heat and pressure
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dense ball of solid Ni (Nickel) and Fe (Iron)
Layers of the Atmosphere
The atmosphere is made up mainly of 3 things:
1.Gases, like oxygen and nitrogen
2.Water vapor (this is what makes the sky blue!)
3.Solid particles, like dust, pollution, and ash from volcanoes
➢These solid particles (mixed with water vapor) are what make up clouds and fog.
The atmosphere is actually made up of 2 main regions. The heterosphere and the homosphere.
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Heterosphere: is the outer most region that actually comes in contact with outer space.
Homosphere: is the region that comes in contact with the surface of the Earth and extends up about 50 miles.
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The atmosphere is made up of 5 separate layers.
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First layer: troposphere - contains almost all of the atmosphere’s
water vapor.
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Second layer: stratosphere - has the important job of blocking most
of the harmful radiation that comes from the sun. The ozone layer is
located in the stratosphere. It contains ozone molecules that absorb
the radiation, so it never reaches the Earth.
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Third layer: mesosphere – it is the coldest of the 5 layers. This layer
stops meteors from crashing to Earth. The low density and cool
temperature causes them to burn up as they travel down to Earth.
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Fourth layer: thermosphere - this layer is very hot but would feel
very cold if you were there.
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Fifth layer: exosphere - outermost layer of the atmosphere before
you actually are in outer space. It has the least amount of molecules
of any of the layers.
Global warming - the gradual heating of Earth's surface, oceans and atmosphere, is caused by human activity, primarily the burning of
fossil fuels that pump carbon dioxide (CO2), methane and other greenhouse gases into the atmosphere.
Theory of Continental Drift
Alfred Wegener proposed that all the continents were once together in a single landmass and
have drifted apart from each other.
Wegener’s theory had three proposals:
 All continents were once together in a supercontinent called Pangaea (All Lands).
 Pangaea existed roughly 225 million years ago.
 Over millions of years, the continents drifted to their present-day locations.
Evidence For Drift:
 Fossil Evidence - Fossils of reptiles and plants were found on widely separated continents.
 Climate Evidence - Fossils of tropical plants have been found in the cold Arctic. Scratches on
rocks from glaciers have been found in warm South Africa.
 Geologic Evidence - Rock types found in Brazil matched rocks found in West Africa.
Limestone layers in America matched with layers in Scotland.
Theory of Plate Tectonics
The theory of plate tectonics states that the lithosphere is made of huge plates that are in
constant, slow motion, driven by convection currents in the mantle.
1. Earth’s lithosphere is broken into separate sections of rock called tectonic plates.
2. Plates fit together along cracks in the crust.
3. Plates carry continental crust, oceanic crust, or a combination of both.
4. The plates are in constant, slow motion, driven by mantle convection currents.
5. As the plates move, they produce changes such as volcanoes, earthquakes, etc.
Plate Boundaries
Tectonic plates move & collide with each other.
A plate boundary is where the edges of two tectonic plates meet.
There are 3 different types:
1. Divergent
2. Convergent
3. Transform
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Stress and Plate Boundaries
Convection Currents
• Convection is the transfer of thermal energy by
particles moving through a fluid. Thermal energy
is always transferred from an area with a higher
temperature to an area with a lower temperature.
• Moving particles transfer thermal energy through a
fluid by forming convection currents.
• Convection currents move thermal energy through
many fluids, including molten rock inside Earth,
water in the oceans, and air in the atmosphere.
A heated substance is less dense than a cold
substance, which causes the hot substance to
rise and cold substance to replace it
Feedback Loops
Positive Feedback Loops
Positive feedback loops: Result in a system
moving to an extreme.
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Positive feedback destabilizes a system
and drives it toward an extreme, it can
alter a system drastically.
Positive feedback loops are relatively
rare in natural environmental systems.
They are, however, common in
environmental systems changed by
people.
Negative Feedback Loops
Negative feedback loops: Result in stabilization of
a system.
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Most systems in nature involve negative
feedback loops.
Negative feedback loops enhance stability,
and in the long run, only stable systems
persist.
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Earth’s “Spheres”
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Earth’s geosphere is made of all the rock at and below Earth’s surface. The lithosphere is the hard rock on and just below Earth’s surface—the
outermost layer of the geosphere.
The biosphere consists of all the planet’s living or once-living things and the nonliving parts of the environment with which they interact.
The atmosphere consists of the layers of gases surrounding our planet.
The hydrosphere encompasses all water—salt, fresh, liquid, ice, and vapor—on Earth’s surface, underground, and in the atmosphere.
Feedback Mechanisms of Climate Change
The earth's climate is in a delicate equilibrium between the energy coming in
from the sun and the energy being reflected back into space from the planet's
surface.
A feedback mechanism is a process that allows a system, such as climate, to
self-regulate in response to a change, such as increasing greenhouse gases.
There are four feedback mechanisms of climate change:
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Ice-Albedo Feedback
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Water Vapor-Cloud Feedback
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Atmosphere-Ocean Interactions
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Atmosphere-Biota Interactions
Feedback can be either positive or negative.
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In positive feedback, the initial effect is enhanced or increased.
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In negative feedback, the initial effect is counteracted or decreased.
Water Vapor-Cloud Feedback (Negative Feedback)
As the planet warms up, the oceans begin to evaporate at a higher rate. This water
vapor in the atmosphere leads to the formation of clouds, or water droplets in the
sky. The clouds (notice that they are white like the snow) reflect the sun's radiation
away from the planet, causing the earth to cool back down. Thus, the water vaporcloud feedback loop keeps the planet from heating up forever.
Atmosphere-Ocean Interactions (Positive Feedback)
Colder water can hold more carbon dioxide than warmer water. As the
atmosphere heats up, so do the oceans. The warming water allows carbon
dioxide to escape into the atmosphere, enhancing the greenhouse effect and
further warming the planet.
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Atmosphere-Biota Interactions (Negative Feedback)
Biota refers to all of the living creatures - plant, animal, or otherwise - in a
particular area.
Ice-Albedo Feedback (Positive Feedback)
Albedo is derived from the Latin term for 'whiteness' and refers to how
reflective a surface is. The more ice there is on the earth's poles, the higher
the earth's albedo.
Plants both on land and in the ocean play a very large role in the stability of our
climate. They are essential in removing carbon dioxide from the atmosphere during
When the earth has a high albedo, more of the sun's radiation is reflected
the process of photosynthesis.
back into space and less is absorbed by the planet. This has the effect of
A warmer climate leads to more plant life. Increased plant life means that more
keeping our planet cooler.
carbon dioxide is removed from the atmosphere and more clouds are added. This
leads to less greenhouse gases trapping heat and more of the sun's rays being
When the sun sends more radiation to the earth's surface, the planet starts to
reflected away from the planet. As a result, the climate cools down.
heat up. This increase in temperature causes the ice at the poles to melt.
Less ice means that the planet's albedo decreases. Less radiation is
reflected back into space and more is absorbed, causing the earth to heat up
even more. A warmer planet means more ice melting, less radiation reflected
back, and more absorbed, and so on. This is called positive feedback.
Earthquakes
An earthquake is a shaking of the ground caused by the sudden movement of rock along a plate boundary.
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Earthquakes happen when a plate scrapes, bumps, or drags
along another plate.
The surface where they slip is called the fault or fault plane.
The location below the earth’s surface where the earthquake
starts is called the hypocenter.
The location directly above it on the surface of the earth is called
the epicenter.
Smaller earthquakes that happen in the same place as the larger
earthquake that follows are called foreshocks.
The largest, main earthquake is called the mainshock.
Aftershocks are smaller earthquakes that occur afterwards in the
same place as the mainshock.
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plates or by volcanic activity
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Seismic Waves
Quake energy is released as seismic waves.
Seismic waves are vibrations caused by earthquakes that carry energy.
There are three different types of seismic waves:
• Primary (P) Waves
• Secondary (S) Waves
• Surface Waves
Primary (P) Waves
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Push and pull the ground like an accordion.
The fastest seismic wave (5 km/s).
Cause the least amount of damage.
Surface Waves
Secondary (S) Waves
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Shake the ground side to side or up and
down.
Slower than P waves (2.5 km/s)
Cause medium amounts of damage.
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Cause the ground to roll up/down and
side/side.
The slowest seismic wave.
Cause the most amount of damage.
Measuring Earthquakes
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Scientists study quakes using seismographs.
A seismograph measures ground movement from seismic waves.
Seismographs show ground movement as wiggles on a paper or computer screen.
This image is called a seismogram.
Earthquake Magnitude
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The strength of an earthquake is its magnitude.
Magnitude is a number given to an earthquake based on its strength.
Geologists use 3 scales:
• Mercalli Scale
o Rates earthquakes according to how much damage they cause
at a certain location.
• Richter Scale
o Rates earthquakes according to the size of their seismic waves.
• Moment Magnitude Scale
o Rates earthquakes according to how much total energy is released.
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Earthquake Damage
Earthquakes can cause damage in many ways.
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Ground Shaking - Ground shaking can crack roads, buildings, dams and other structures.
Aftershocks - An aftershock is a smaller earthquake that follows a more powerful earthquake.
Landslides - The shaking from seismic waves can trigger landslides or avalanches.
Liquefication - Liquefaction is when the shaking of the ground causes soil to act as a liquid.
Tsunami - A tsunami is a giant wave produced when earthquakes displace water.
Volcanoes
Volcanoes are vents in the earth's crust through which lava, rock fragments, hot vapor, and gases are ejected.
There are different types of volcanoes based on their size, shape, composition, and eruptive style.
Volcanoes have distinctive features:
• magma chamber - this is where the molten rock is stored beneath the ground
• main vent - this is the channel through which magma travels to reach the Earth's surface
• secondary vent - some magma may escape through the side of the volcano,
particularly if the main vent becomes blocked
• crater - this is found at the top of the volcano, where the magma erupts from
The Ring of Fire has 80% of the world’s volcanoes.
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The Ring of Fire is a belt of volcanoes on the edge of the Pacific Ocean.
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The ring is a series of convergent boundaries, where the Pacific plate subducts
below various continental plates.
The type of magma (thick or thin) determines a volcano’s shape.
There are three different types:
• Composite Cone Volcanoes
• Shield Volcanoes
• Cinder Cone Volcanoes
Composite Cone Volcanoes
A composite cone volcano is a steep, cone shaped
mountain.
• Built from alternating layers of rock fragments
and lava.
• Thick, syrupy lava.
• Eruptions are violent and unpredictable
Shield Volcanoes
A shield volcano is a very wide, gently sloping
mountain.
• Built up from many thin layers of runny lava
that has hardened over time.
• These volcanoes can cover large areas.
• Eruptions are very frequent, but mild.
Cinder Cone Volcanoes
A cinder cone volcano is a steep-sided hill made
from volcanic rock fragments.
• Built when eruptions of cinders and fragments
pile up around one vent.
• No lava: fragments only.
• Eruptions are frequent and explosive.
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Lava is liquid rock at the Earth’s surface.
Magma is liquid rock below the surface.
There are 2 different types of lava:
Thick (aa)
• High in silica.
• Flows very slowly.
• Explosive eruptions.
• Infrequent eruptions.
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Low in silica.
Flows very easily.
Weak eruptions.
Frequent eruptions.
Thin (pahoehoe)
Types of Volcanoes
Volcanoes are classified by their activity:
Active
Dormant
Extinct
• Is erupting or shows signs it may erupt in
the near future.
• Not active now but may become active in
the future.
• Has erupted, before, but is unlikely to erupt
again.
Weathering, Erosion, and Deposition
Weathering
Weathering:- The process of breaking down rock on Earth’s surface. Rocks are broken down into smaller and smaller pieces and eventually help to create soil
2 types of weathering – mechanical and chemical
• Mechanical Weathering – the process in which rock is physically broken into smaller pieces
• Chemical Weathering – the process that breaks down rock through chemical changes
Mechanical Weathering
Chemical Weathering
There are 6 main types of mechanical weathering:
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There are 4 main types of chemical weathering:
Frost Wedging – water seeps into the cracks of rocks, freezes, and
expands to break rocks apart
Root Wedging – plant roots grow larger and larger in the cracks of rocks
and eventually break rocks apart
Salt Wedging – water seeps into the cracks of rocks and evaporates
leaving salt behind; salt forms salt crystals over time that break rocks
apart
Abrasion – rocks are broken down by moving particles carried by wind,
water, ice, or gravity
Exfoliation – outer layers of rocks weather and peel off in thin sheets
Thermal Expansion – the heating and cooling of rocks due to
environmental conditions throughout the year; constant expanding and
contracting causes rocks to break over time
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Oxidation – occurs when oxygen dissolves in water and combines with
minerals in rocks, reducing their resistance to weathering
Carbonation – the mixing of water with carbon dioxide to make carbonic
acid
Hydrolysis – water reacts with rocks and changes the chemical
composition of minerals, reducing their resistance to weathering
Dissolution – the process of rocks dissolving when exposed to rainwater
Erosion
Erosion - The process by which water, ice, wind, or gravity moves pieces of rock or soil.
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Rock or soil is moved to a new location
Sediment - small, solid pieces of material from rocks or organisms
3 processes that cause erosion – waves, moving water, and wind
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Mass Movement
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Movements of large masses of rock, soil, or mud
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Occurs along the sides of steep hills and mountains
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There are 4 main types of mass movement – landslide, mudflow, slump, and creep
Deposition
Deposition - The process by which sediment settles and is deposited in a new location.
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Sediment is deposited by wind, water, and ice.
Builds up new land on Earth’s surface
3 major landforms created by deposition – deltas, alluvial fans, and moraines
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Delta – a landform of sediment deposited where a river flows into an ocean.
Alluvial Fan – a deposit of sediment formed where a stream leaves a mountain range.
Moraine – a mass of sediment carried down and deposited by a glacier.
Examples:
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A river delta forming as a river flows into an ocean.
An alluvial fan forming at the base of a mountain stream.
A glacier dropping rock and other debris to form a moraine.
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