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EARTH SYSTEMS
Chapter 8
Part 1 – Tectonic Cycle
STNT 35
Your questions and key for your test
Case Study – Hybrid Vehicles
1. What is the benefit of hybrid vehicles?
2. What are the drawbacks of hybrid vehicles?
3. What is believed to be the limiting factor for
the production of hybrid vehicles? Explain.
4. What is the environmental concern in
addition to the limiting factors for hybrid
vehicles? Explain.
5. What are the environmental problems of
surface mining for the metals needed?
When?
How?
• Originally the earth was a
molten sphere with some
debris added from the sun
formation.
• As the molten material cooled,
the elements separated into
layers: heavier ones sinking,
lighter ones rising.
Elements and Minerals?
• Nearly all the elements on
earth are as old as the planet.
• Distribution of the elements
and minerals.
Earth Formation
Vertical Zonation
Innermost zone
Mantle
• Convection cells
• Asthenosphere
• Solid Upper layer
Lithosphere
• Large and small plates
Crust
Earth’s Layers
• A wedge from Earth would cover the width of
the U.S.
Earth’s Geologic Cycle
Three major processes of the geologic cycle
• Tectonic cycle
• Rock cycle
• Soil formation
Convection and Hot Spots
High temperature of Earth’s outer core and mantle
convection cells
• Radioactive decay
Result of the high temperature
• Plumes of hot magma
• Hot spots
• Convection cells
Results of convection cells
Theory of Plate Tectonics
The earth’s lithosphere is divided into plates,
most of which are in constant motion.
Tectonics Cycle
All the processes that
build up and break down
the lithosphere.
Evidences?
Add to Laws
Tectonic Cycle
Two types of plates of
the lithosphere.
Movement of the
plates?
Seafloor spreading.
Subduction
Consequences of Plate Movement
Geologic time scale.
Results of continental drift?
Current Era/Period
Results of plates moving
continents to different areas
or breaking continents apart?
• Volcanoes
• Earthquakes
• Seafloor spreading
• Mountain formation
Volcanoes
• Most along plate boundaries.
• A vent in Earth’s surface that
emits ash, gases and molten lava.
Natural source of:
• CO2
• Sulfur
• Particulates
• Metals from the core
Islands still forming
The Hawaiian Islands Volcanic Arc
Iceland Volcanic Eruption
• Iceland volcanic eruption
in 2010:
– Suspended air travel in
many parts of Europe.
– Ash contained silicon
dioxide which is harmful
to airplane engines.
Plate Movement Simulation
• Purpose
– To simulate the three types of tectonic plate
movements.
• Materials – Oreo Double Stuff Cookie
– Upper cookie is the lithosphere
– Creamy filling is asthenosphere
– Lower cookie is the lower mantle
Procedure
• Carefully remove the upper cookie (a
twisting motion is required)
• Slide the upper cookie over the
creamy filling to simulate motion of a
rigid lithospheric plate over the
softer asthenosphere.
• Break the upper cookie in half.
– Listen to the sound it makes when you
break it.
– What does that sound represent?
Types of Tectonic Plate Contact
Divergent plate boundaries
• Oceanic and oceanic plate contact
• Continental and continental plate conact
Simulation of Divergent Plate
Boundary
• Push down on the two
broken cookie halves and
slide them apart.
• Notice that the creamy
filling between the two
broken “plates” may tend
to flow upward, similar to
the rising, decompression
and partial melting of hot
asthenosphere at sea floor
spreading and continental
rifts.
Convergent Plate Contact
Convergent plate contact.
• Oceanic and continental plates
• Continental and continental plates
• Oceanic and oceanic
Simulation of Convergent Plate
Boundary
• Push one cookie piece
beneath the other.
• Notice what happens
to each cookie piece.
• What is this
movement called?
• What plates will
produce this
movement?
Transform Fault
Description
• Fault
• Fault zone
Results
Simulation of Transform Plate
Boundary
• Slide the two cookie pieces
laterally past one another
over the creamy filling.
• You can feel and hear the
“plates” do not slide
smoothly past one another
but rather stick and then let
go, stick and then let go.
• The cracking you hear each
time is like an earthquake
occurring along the San
Andreas Fault.
Do the Math
• Los Angles is 630km (380mi) southwest of San
Francisco. The plate under LA is moving 36
mm/year toward San Francisco. How long
before they are side by side?
Time = distance
rate
Add to your formula page
Earthquakes
• Internal geological process from vibrations from plate
movements.
– Releasing energy causing a shift or break in the earth’s
crust.
•
•
•
•
Focus
Epicenter
Seismic waves.
Measurement
Richter Scale
• Charles Richter – devised
the seismograph
•
•
•
•
•
•
Insignificant – <than 4
Minor – 4.0 – 4.9
Damaging – 5.0 – 5.9
Destructive – 6.0 – 6.9
Major – 7.0 – 7.9
Great – Over 8.0
Haiti earthquake in 2010
Chili Largest earthquake in 1960
7.0
9.5
U.S. Earthquake Risk
Global Earthquake Risk
Tsunami
•
•
•
•
Definition
Cause
Formation
Role of coral reefs,
mangrove forests
and other wetlands.
Largest in 2004 by an earthquake (
9.1) in the Indian Ocean affecting
Indonesia, Thailand, Sri Lanka, South
India and East Africa.
Chapter 8
Part 2
Geologic Cycle – 2nd Process
Rock cycle
• Constant formation and destruction of rock.
• Slowest of all Earth’s cycles
Difference between a rock and a minerals?
Rock Cycle
• Relationship
between magna
and rock.
• Three ways rocks
are formed.
• Three types of
rocks.
Classification of Rocks
• Formation of each type of rock.
– Igneous
– Sedimentary
– Metamorphic
Weathering
Define weathering.
Explain physical and biological weathering.
Physical
Biological
Chemical Weathering
Explain chemical
weathering.
• CO2 + H2O H2CO3
– Carbonic acid.
– Dissolves limestone.
• Anthropogenic
– SO2 + H2O  H2SO4
– Acid rain – Sulfuric Acid
Erosion
• Define erosion.
• Explain how erosion is
different from
weathering.
• Explain the 2
mechanisms causing
erosion.
• What is deposition?
• Identify some natural
causes of erosion.
• Identify some
anthropogenic causes of
erosion.
Soil Formation 3rd Process
• Soil
– Mixture of
geologic and
organic
components
• Functions of
soil.
The Formation of Soil
• From hundreds to thousands of years.
– Result of weathering of rocks and gradual
accumulation of detritus from the biosphere.
– Wind and erosion
– From top down and bottom up
– Young soil, mature soil, old soil
Factors Determining Properties of Soil
How these factors determine the properties of
soil:
• Parent material
• Climate
• Topography
• Organisms
• Time
Soil Horizons (layers)
•
•
•
•
•
O horizon
A horizon
B horizon
C horizon
E horizon
Physical Properties of Soil
• Sand, silt and clay are mineral particles of
different sizes.
• Texture of soil
– % of sand, silt, clay
– Sum always 100%
Soil Texture Chart
• Determine the
texture of soil that is
60% silt, 30% sand
and 10% clay.
Physical Properties of Soil
Porosity
• How much space is located between the particles that
contains air, water
Permeability of soil
• How quickly it drains - Depends on its texture
– Sand
– Silt
– Clay
– What is the best agricultural soil? Why?
• What is the problem associated with very sandy soils?
• Why are landfills lined with clay?
Chemical Properties of Soil
• Clay particles contribute the most to the
chemical properties of soil
– Cations – positively charged mineral ions
– Clay particles are negatively charged
– CEC cation exchange capacity
• What is the CEC most desirable for
agriculture and why?
• Tradeoff between CEC and permeability
Chemical Properties – Acids and Bases
• Soil bases
– Calcium, magnesium, potassium, sodium
• Soil acids
– Aluminum, hydrogen
• Which is better for plant growth? Why?
• Base saturation
Biological Properties of Soil
• Common organisms in
the soil
• Rodents/earthworms
• Snails/slugs
• Soil bacteria
• Classification of most
organisms in the soil.
– Function
Soil Degradation and Erosion
• Soil degradation
– Loss of some or all of
the ability of the soil to
support plant growth.
• Causes
– Compaction
– Soil drying
• Major cause – soil
erosion
• Which horizon contains
the topsoil?
• Why is topsoil loss so
damaging?
Mineral Resources
• Crustal abundance
• Four elements that make
up 88% of the Earth’s
crust.
• Ore
– Concentrated abundance of
minerals from which
economically valuable
material can be extracted.
– May contain metals or not
• Metals.
Reserve – known quantity of the resource that can
economically recovered.
Mineral Resources
• Mining.
– Extraction from the earth of the ore
– Separation desired materials out of the ore
• Two types of mining
– Surface mining
– Subsurface mining
• Mineral resource or mineral deposit
– Concentration of a natural substance in crust that
can be extracted and processed into useful products
at an affordable cost.
Surface Mining
• Four types of surface
mining:
• Strip mining
– Removal of strips of
soil and rock to expose
ore close to the
surface.
– Use often to mine coal
and sand.
• Mining spoils or tailings.
Open-pit mining
• Creation of a large pit or hole in the ground.
• When the resource is close to the surface but extend
beneath the surface both horizontally and vertically.
Kennecott Bingham Canyon
Mine - Utah
• Copper mine
• One of the largest open-pit
mines in the world.
Mountaintop Removal
• Removal of the entire
top of a mountain with
explosives.
– Generally coal mining
– In the Appalachian area,
470 of the largest
mountains are gone.
– Tailings often erode or
leach into mountain
streams.
Placer Mining
• Process of looking for
metals and precious
stones in river
sediments.
• Use of river water to
separate the ore.
• Diamonds, gold
Illegal tropical placer mining.
Using water cannons to wash
entire hillside into collection
boxes.
Subsurface Mining
• Removal of deep deposits.
• Horizontal and vertical shafts.
Comparison of Surface and Subsurface
Mining
Advantages and Disadvantages of
Mining
• Advantages of mining.
– Economics
– Jobs
– Resources for manufacturing
• Disadvantages of mining.
–
–
–
–
–
Disturbance of soil
Degradation/fragmentation of habitats
Erosion
Soil, air and water pollution
Subsurface – dangerous to workers/ lung diseases
Distribution of Mineral Resources
• The most – U.S. Canada, Russia, South Africa,
Australia
• South Africa
– Nearly self-sufficient in world’s key resources.
– Largest producer of
• Gold
• Chromium
• Platinum
Nonrenewable Minerals
•
Supply
• Actual or potential supply
• Rate of use
•
•
•
Economically depleted
• When it costs more than it is worth to find, extract,
transport and process the remaining deposits.
Recourses when the supply is economically depleted
• Reuse or recycle
• Waste less
• Use less
• Find a substitute
• Do without
Depletion of Nonrenewable Mineral
Resources.
• Depletion time
• Time it takes to use up 80%
or the reserves at a given
rate of use.
• Dashed vertical lines show
when 80% depletion occurs.
Mining Laws
• Early mining laws focused primarily on
promoting economic development.
• Later laws were concerned with worker safety
and environmental protection.
U.S. General Mining Law of 1872
• Governs hardrock mining (gold, copper, silver,
etc.) on America's public lands.
• Congress was trying to encourage settlement
of the American West by offering free
minerals and land to those who were willing
to settle out West and mine.
• Currently, mining companies are allowed to
buy up America's public lands for $5 or less
per acre.
Add laws to your binder.
• Additionally, the mining industry, unlike coal and
oil companies, is not required to pay production
royalties or rental fees for the use of public land,
and there are few environmental standards or
requirements governing cleanup.
• In fact, hardrock mining pours more toxics into
the environment than any other industry in the
country .
• The federal government currently interprets the
1872 Mining Law as mandating that mining is the
highest and best use for public lands.
SMCRA
• Surface Mining Control and Reclamation Act.
– Regulates surface mining of coal and the surface
effects of subsurface coal mining.
– Act mandates that land be minimally disturbed
during the mining process and reclaimed after
mining is completed.
– Requires restoration of abandoned mines.