Download Geology and Nonrenewable Minerals

Core Case Study:
Environmental Effects of Gold Mining
What countries mine the most gold?
South Africa
Australia
United States
Canada
What is cyanide heap leaching?
To extract gold, miners spray a solution of highly toxic
cyanide salts (which react with gold) onto huge open-air
piles of crushed rock.
Gold Mine with Cyanide Leach Piles and Ponds in South Dakota
Ryan would take all his notes
Complete Cornell Notes for all 5 objectives and the answers the 3 summary questions
Geology and
Nonrenewable Minerals
Chapter 14
Objective 1
What Are the Earth’s Major Geological
Processes and Hazards?
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The Earth Is a Dynamic Planet

What is geology?
◦ The science devoted to the student of dynamic
processes occurring on the earth’s surface and
interior

Three major concentric zones of the earth
◦ Core – inner most zone
◦ Mantle – surrounding the core
 Including the asthenosphere
◦ Crust – outermost and thinnest layer
 Continental crust – underlies the continents
 Oceanic crust: 71% of crust
The Earth Beneath Your Feet Is Moving

We tend to think of earth’s crust, mantle, and
core as fairly static. In reality, convection cells,
or currents move large volumes of rock and
heat in loops within the mantle like a gigantic
conveyer belt.

Tectonic Plates move extremely slow atop the
denser mantle on soft rock in the underlying
asthenosphere

Lithosphere are thick plates composed of the
continental and oceanic crust and the rigid,
outermost part of the mantle.
The Earth’s Major Tectonic Plates
Three types of boundaries between plates
1) Divergent plates - move apart
 Magma – molten rock flows up through the resulting cracks.
 Oceanic ridge – is created when plate diverge
2) Convergent plates – oceanic plates collides with a
continental plate
 Subduction – continental plate rides up over the denser
oceanic plate and pushes it down into the mantle
 Subduction zone – the area where the collision and
subduction take place
 Trench – forms at the boundary between the two converging
plates
3) Transform fault – plates slide and glide past one
another along a fracture (fault) in the lithosphere
example: San Andreas fault
The Earth’s Crust Is Made Up of a Mosaic of Huge Rigid Plates:
Tectonic Plates
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The San Andreas Fault as It Crosses Part of the
Carrizo Plain in California, U.S.
Some Parts of the Earth’s Surface Build Up and
Some Wear Down

Internal geologic processes
◦ Generated by heat from the earth’s interior, generally
build up the earth’s surface in the form of continental
and oceanic crust

External geologic processes
◦ Weathering
 Physical, Chemical, and Biological
 Driven by the energy from the sun and influenced by gravity,
tend to wear down the earth’s surface
◦ Erosion – dissolved, loosened, or worn away
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Wind
Flowing water
Human activities
Glaciers – under the influence of gravity, glaciers move slowly
down a mountain side or over a wide area
Biological, Chemical, & Physical Processes
Copy Figure 14-6
in your notes
Volcanoes Release Molten Rock from the Earth’s Interior

Volcano – occurs where magma reaches the
earth’s surface through a central vent or a long
crack (a.k.a. fissure)
◦ Magma – molten rock
◦ Lava – magma that reaches the earth’s surface

1980: Eruption of Mount St. Helens
◦ The worst volcanic disaster in US history

1991: Eruption of Mount Pinatubo
◦ The largest volcanic eruption during the 20th century

Benefits of volcanic activity – highly fertile soil
Creation of a Volcano
Pompeii
Earthquakes Are Geological
Rock-and-Roll Events

Earthquake
◦ Seismic waves – vibrations
◦ Focus – the place where the earth quake begins
◦ Epicenter – the earth’s surface directly above
the focus
◦ Magnitude – the severity of an earthquake
◦ Amplitude – size of the seismic waves
 Richter scale
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Insignificant: <4.0
Minor: 4.0–4.9
Damaging: 5.0–5.9
Destructive: 6.0–6.9
Major: 7.0–7.9
Great: >8.0
Major Features and Effects of an Earthquake
Areas of Greatest Earthquake Risk in the United States
Areas of Greatest Earthquake Risk in the World
Earthquakes on the Ocean Floor Can
Cause Huge Waves Called Tsunamis
Tsunami a.k.a tidal wave – a series of
large waves generated when part of the ocean
floor suddenly rises or drops
 December 2004: Indian Ocean tsunami

◦ Magnitude of 9.15
◦ Waves as high as 31 meters (100 feet)
Formation of a Tsunami and Map of Affected Area of Dec 2004 Tsunami
Shore near Gleebruk in Indonesia before
and after the Tsunami on June 23, 2004
Objective 2
How Are the Earth’s Rocks Recycled?
Copy Figure 14-13
in your notes
There Are Three Major Types of Rocks

Earth’s crust is Composed of
• Minerals – an element or inorganic compound that
occurs naturally in the earth’s crust
• Rocks – a solid combination of one or more minerals
found in the earth’s crust
(we will talk more about minerals next objective)
Examples of mineral resources are
fossil fuels (coal, oil, and natural gas)
metallic minerals (such as aluminum, iron, and copper)
nonmetallic minerals (such as sand, gravel, & limestone)
As they take so long to produce, these components of the
earth’s natural capital are classified as nonrenewable mineral
resources.
The Earth’s Rocks Are Recycled Very Slowly
Rock cycle – the interaction of physical and
chemical processes that change rocks from
one type to another
 Slowest of the earth’s cyclic processes

Three broad classes of rocks, based on
formation
1.
Igneous rock is formed below or on the earth’s
surface when molten rock wells up and hardens.
They form the bulk of the earth’s crust.
2.
Sedimentary rock is formed from small, eroded
pieces of rock that are carried to downhill sites.
Layers accumulate over time and an increase of
weight and pressure plus dissolved minerals bind the
sediment particles together to form sedimentary
rock.
3.
Metamorphic rock is produced from preexisting
rock that is subjected to high temperatures, high
pressures, chemically active fluids, or some
combination of these.
Three broad classes of rocks, based on formation
1. Sedimentary – made of sediments
• Examples of sedimentary rock
•
•
•
•
•
•
Sandstone
Shale
Dolomite
Limestone
Lignite
Bituminous coal
2. Igneous – forms below or on the earth’s
surface when magma cools and hardens
 Examples of igneous rock
 Granite
 Lava rock
3. Metamorphic – pressure and heat
 Examples of metamorphic rock
 Anthracite
 Slate
 Marble
Objective 3
What Are Mineral Resources, and what are
their Environmental Effects?
We Use a Variety of Nonrenewable Mineral Resources

Mineral resource
◦ Fossil fuels – like coal
◦ Metallic minerals – like aluminum, iron, & copper
◦ Nonmetallic minerals – like sand, gravel, & lime
stone

Ore
◦ After waste material is removed from metal ores
they are smelted or treated with chemicals to
extract the desired metal.
 High-grade ore – contains large amounts of the
desired nonrenewable mineral
 Low-grade ore – contains a smaller amount of the
mineral
Mineral resources can be classified into
four major categories:
1.
Identified resources with a known location,
quantity, and quality.
2.
Reserves are identified resources that can be
extracted profitably at current prices.
3.
Undiscovered reserves are potential supplies
of a mineral resource assumed to exist.
4.
Other resources are undiscovered resources
and identified resources not classified as
reserves.
The Life Cycle of a Metal Resource
Copy Figure 14-15 in your notes
There Are Several Ways to Remove Mineral Deposits

Surface mining
◦ Shallow deposits removed

Subsurface mining
◦ Deep deposits removed
Overburden – the soil and rock overlying a
useful mineral deposit
 Spoils – the overburden that is discarded as
waste material

There Are Several Ways to Remove Mineral Deposits

Types of surface mining
◦ Open-pit mining – machines dig holes and
remove ores
◦ Strip mining – gigantic earthmovers strip away
the overburden, and power shovels remove the
mineral deposit
◦ Contour mining – is used mostly to mine coal
on hilly or mountainous terrain
◦ Mountaintop removal – explosives, large
power shovels, and huge machines are used to
remove the top of a mountain and expose coal
Open-Pit Mine in Western Australia
Contour Strip Mining Used in Hilly or Mountainous Region
Mountaintop Coal Mining in West Virginia, U.S.
Mining Has Harmful Environmental Effects

Scarring and disruption of the land surface
◦ E.g., spoils banks

Loss of rivers and streams

Subsidence – collapse of land above some
underground mines

Major pollution of water and air

Effect on aquatic life

Large amounts of solid waste
Banks of Waste or Spoils Created by Coal
Area Strip Mining in Colorado, U.S.
Illegal Gold Mine
Ecological Restoration of a Mining Site
in New Jersey, U.S.
Natural Capital Degradation: Summitville Gold
Mining Site in Colorado, U.S.
Objective 4
How Long Will Supplies of Nonrenewable
Mineral Resources Last?
Mineral Resources Are Distributed Unevenly

Most of the nonrenewable mineral resources
are supplied by
◦
◦
◦
◦
◦
United States
Canada
Russia
South Africa
Australia
Supplies of Nonrenewable Mineral Resources
Can Be Economically Depleted

Future supply depends on
◦ Actual or potential supply of the mineral
◦ Rate at which it is used

When it becomes economically depleted
◦
◦
◦
◦
◦
Recycle or reuse existing supplies
Waste less
Use less
Find a substitute
Do without
Depletion Curves for a Nonrenewable Resource
Read the case study on page 363
The U.S. General Mining Law of 1872

Encouraged mineral exploration and mining of
hard-rock minerals on U.S. public lands to
boost development on the then-sparsely
populated West

Until 1995, land could be bought for 1872
prices

Companies must pay for clean-up now
Is Mining Lower-Grade Ores the Answer?

Factors that limit the mining of lower-grade ores
◦ Increased cost of mining & processing larger volumes of
ore
◦ Availability of freshwater needed to mine and process
some minerals
◦ Environmental impact
 Land disruption, waste materials, and pollution produced

Improve mining technology
◦ Use microorganisms to extract minerals
 in-place or in situ in SY-too mining
 Downside is that it is a slow process
◦ Biomining
 Genetic Engineering techniques that can produce
bacteria
Objective 5
How Can We Use Mineral Resources More
Sustainably?
We Can Find Substitutes for Some Scarce Mineral Resources

Materials revolution
◦ New materials are being used as replacements
for metals
◦ For example, development of silicon and ceramics
may replace the need for as much metal.

Nanotechnology – tiny tech
◦ Uses science and engineering to manipulate and
create materials out of atoms and molecules.
We Can Recycle and Reuse Valuable Metals

Recycling
◦ Lower environmental impact than mining and
processing metals from ores
 Example – Recycling aluminum beverage cans and scrap
aluminum produces 95% less air pollution and 97% less water
pollution and uses 95% less energy than mining and
processing aluminum ore.

Growing signs point to an ecoindustrial
revolution taking place over the next 50 years.
The goal is to make industrial manufacturing
processes cleaner and more sustainable by
redesigning them to mimic how nature deals
with wastes.
Copy Figure 14-24
in your notes
An Industrial Ecosystem in Denmark Mimics Natural Food Web
Can you answer these questions?
1. Which rock type is made from lava?
Igneous
2. Which rock type is made from lithified sediments?
Sedimentary
3. Which rock type is made from the compression of the two other
rock types?
Metamorphic
4. Which mechanical process leads to the formation of sediment?
Weathering
5. What are the two types of igneous rocks?
Granite (formed underground) & lava rock (formed aboveground)
Summary
 Briefly
describe the three major classes
of rocks, including how they are
formed and examples of each type.
 Explain
what it means for a mineral to
become economically depleted.