geology and nonrenewable minerals ap environmental science
TRANSCRIPT
Geology and Geology and Nonrenewable MineralsNonrenewable Minerals
AP Environmental Science
14-1. What Are The Earth’s Major Geological 14-1. What Are The Earth’s Major Geological Processes and Hazards?Processes and Hazards?
• Gigantic plates in the Earth’s crust move very slowly atop the planet’s mantle, and wind and water move matter from place to place across the Earth’s surface.
• Natural geological hazards such as earthquakes, tsunamis, volcanoes, and landslides can cause considerable damage.
• Gigantic plates in the Earth’s crust move very slowly atop the planet’s mantle, and wind and water move matter from place to place across the Earth’s surface.
• Natural geological hazards such as earthquakes, tsunamis, volcanoes, and landslides can cause considerable damage.
Earth: The Dynamic PlanetEarth: The Dynamic Planet
• Earth is divided into three main “zones”:– Crust: Hard, cracked outer shell
(Crust + Solid Mantle = Lithosphere)
– Mantle: Softer rock, liquid to hard(Softer layer of mantle = Asthenosphere)
– Core• Inner: Hottest & under greatest pressure - solid• Outer: Extremely hot, but liquid
Natural Processes Shape EarthNatural Processes Shape Earth
• Internal Processes– Usually “build up” the
Earth’s surface
• External Processes– Usually “wear down” the
Earth’s surface– Physical weathering:
Wind, rain, freezing, etc.– Chemical weathering:
Water, acids, gases, etc.– Biological weathering:
Living things break up parent material
How We Go Places: Plate TectonicsHow We Go Places: Plate Tectonics
• The crust is cracked into large slabs called tectonic plates and float on magma
• Convection currents move plates around• Collisions between plates cause EQ!
Earth’s Major PlatesEarth’s Major Plates
Types of Plate BoundariesTypes of Plate Boundaries
• Where plates meet = plate boundaries– Convergent
• Plates come together, usually one dives under another (subduction)
– Divergent• Plates move apart, magma bubbles up (ridges)
– Transform• Plates move side to side
Plate BoundariesPlate Boundaries
Effects of Plate TectonicsEffects of Plate Tectonics
• Volcanoes– Large hill/mountain formed due to magma
reaching the surface
• Earthquakes– Sudden release of stored up energy from
plates rubbing together
Earthquake TermsEarthquake Terms
• Focus: The true location of an EQ• Epicenter: Location of EQ on surface• Richter Scale: Used to quantify EQ’s energy• Amplitude: Size of EQ wave on seismograph• Aftershocks: Smaller
shakings after EQ• P-Wave: Primary wave• S-Wave: Secondary wave
Tsunami!Tsunami!
• Series of waves generated by EQ• No “Day After Tomorrow” surfer waves• Can cause widespread
devastation
Tsunami Before & AfterTsunami Before & After
Banda Aceh Shore, IndonesiaTsunami of December 28, 2004
Before After
168,000 people died
14.2 How Are The Earth’s Rocks Recycled?14.2 How Are The Earth’s Rocks Recycled?
• The three major types of rocks found in the Earth’s crust – sedimentary, igneous, and metamorphic – are recycled very slowly by the processes of erosion, melting, and metamorphism.
• The three major types of rocks found in the Earth’s crust – sedimentary, igneous, and metamorphic – are recycled very slowly by the processes of erosion, melting, and metamorphism.
The Three Types of RocksThe Three Types of Rocks
• Sedimentary– Small particles pressed together
• Igneous– Rock that forms below surface, wells up and
cools off• Metamorphic
– Igneous or sedimentary rock is exposed to heat, pressure, and chemical changes
How Sedimentary Rock is FormedHow Sedimentary Rock is Formed
• Parent is weathered into small pieces (sediment)
• Sediments are deposited (usually layer after layer)
• Pressure compacts and cements sediment into rock
• Erosion can turn rock back into sediment
How Igneous Rock is FormedHow Igneous Rock is Formed
• Igneous rock starts as magma• As it surfaces, it cools and solidifies –
depending on how it happens, different results:– Extrusive – cooling above ground, quick, only
small crystals form– Intrusive – cooling below ground, slow, larger
crystals form
Examples of Igneous RockExamples of Igneous Rock
Diorite – intrusive
(notice the large crystals/grains)
Obsidian – extrusive
(notice lack of crystals/grains)
How Metamorphic Rock is FormedHow Metamorphic Rock is Formed
• Hardest to identify• Igneous and sedimentary rock can be
turned into metamorphic rock through the use of heat and pressure
• Heat and pressure causes a literal “metamorphosis” to occur as rocks are rearranged
Examples of Metamorphic RockExamples of Metamorphic Rock
Gneiss(“nice”)
Marble
The Rock CycleThe Rock Cycle(You need to KNOW this!)(You need to KNOW this!)
A SLOW series of chemical orphysical processes that canchange one type of rock intoanother
14.3 What Are Mineral Resources and What Are The 14.3 What Are Mineral Resources and What Are The Environmental Effects of Using Them?Environmental Effects of Using Them?
• Some naturally occurring materials in the Earth’s crust can be extracted and made into useful products in processes that provide economic benefits and jobs.
• Extracting and using mineral resources can disturb the land, erode soils, produce large amounts of solid waste, and pollute the air, water, and soil.
• Some naturally occurring materials in the Earth’s crust can be extracted and made into useful products in processes that provide economic benefits and jobs.
• Extracting and using mineral resources can disturb the land, erode soils, produce large amounts of solid waste, and pollute the air, water, and soil.
MineralsMinerals
• Mineral Resource: Naturally occurring, inorganic, material from crust
• Ore: Rock that contains a large concentration of a mineral– High Grade Ore: Large amount of mineral– Low Grade Ore: Smaller amount of mineral
Ore ExamplesOre Examples• If you can’t grow it, you have to MINE it!
Element Ore
Silicon Quartz
Aluminum Bauxite
Iron Magnetite or Hematite
Calcium Gypsum or Calcite
Sodium Halite
Magnesium Magnesite or Dolomite
Potassium Sylvite
Copper Chalcopyrite
Tin Cassiterite
Lead Galena
Zinc Sphalerite
Estimating Mineral ResourcesEstimating Mineral Resources
• Key terms used by USGS:– Identified: location, quantity, and quality
known based on direct measurements.– Undiscovered: potential supplies assumed to
exist.– Reserves: identified resources that can be
extracted profitably.
Effects of Mineral UseEffects of Mineral Use
• No matter the mineral, all steps use large amounts of energy and creates pollution.
• High grade = less energy needed• Low grade = more energy needed
Harmful EffectsHarmful Effects
Extracting Minerals from DepositsExtracting Minerals from Deposits
• Surface Mining– Remove overburden (discarded as spoils) to
get to mineral deposits
• Types– Open-Pit– Strip– Contour Strip– Mountain-Top Removal
Open Pit MiningOpen Pit Mining• Machines dig large holes in ground, remove ores• Toxic water can collect at bottom of pit
Strip MiningStrip Mining
• Similar to open-pit, but only useful when deposits are horizontal and near surface
Contour Strip MiningContour Strip Mining
• Used in hilly or mountain areas
• Cut terraces• Remove
overburden and use to make new terrace
Mountain-Top RemovalMountain-Top Removal• Literally remove the top of mountains (!!!)
Mountain-Top Removal ExampleMountain-Top Removal Example
Removing Metals from OresRemoving Metals from Ores
• Negative consequences:– Scarring/disruption of land surface– Large amount of spoils– Large amounts of solid waste– Toxic or acidification of water (H2SO4, etc.)– Gangue (“gang”)– Air pollution
14.4 How Long Will Supplies of 14.4 How Long Will Supplies of Nonrenewable Mineral Resources Last?Nonrenewable Mineral Resources Last?
• All nonrenewable mineral resources exist in finite amounts, and as we get closer to depleting any mineral resource, the environmental impacts of extracting it generally become more harmful.
• An increase in the price of a scarce mineral resource can lead to increased supplies and more efficient use of the mineral, but there are limits to this effect.
• All nonrenewable mineral resources exist in finite amounts, and as we get closer to depleting any mineral resource, the environmental impacts of extracting it generally become more harmful.
• An increase in the price of a scarce mineral resource can lead to increased supplies and more efficient use of the mineral, but there are limits to this effect.
Depletion of ResourcesDepletion of Resources
• Future supply depends on two factors:– Actual supply– Rate of use
• Depletion time– Use up 80% of resource
• After depletion:– Recycle, waste less, use
less, find a substitute, do without
RESERVES (known supplies)
OTHER RESERVES (potential supplies)
IDENTIFIED UNDISCOVERED
SUBE
CON
OM
IC
ECO
NO
MIC
Increasingly uncertainty
Incr
easi
ng c
ost
RESERVES (known supplies)
OTHER RESERVES (potential supplies)
IDENTIFIED UNDISCOVERED
SUBE
CON
OM
IC
ECO
NO
MIC
Increasingly uncertainty
Incr
easi
ng c
ost
Economic DepletionEconomic Depletion
• As known resources are depleted, it becomes more expensive and difficult to get to new supplies
• We might still have resources left, but it will be TOO COSTLY to utilize them on a wide-scale
U.S. General Mining Law of 1872U.S. General Mining Law of 1872
• To encourage mining of “hard rock” minerals• How it works:
– File claim that you believe land contains valuable minerals– Promise to spend $500 to improve it– Purchase public land for $2.50 to $5.00 an acre (!!!)– Pay $120 a year for each 20-acre parcel of land
• Law frozen in 1995 – by that time, estimated $285 billion of public land “given away” at 1872 prices
• Since clean up requirements only came in 1992, there are an estimated 500,000 sites that will cost taxpayers $32-72 billion to clean up!
Example of 1872 Law “Give Away”Example of 1872 Law “Give Away”
• In 2004, a mining company purchased 155 acres of public land near Crested Butte for $875
• Land could be worth $155 million• Each year, companies remove $4 billion
worth of minerals each year and only pay 2.3% of the value in tax (compared to 13.2% for oil or 14% for grazing rights)
14.5 How Can We Use Mineral 14.5 How Can We Use Mineral Resources More Sustainably?Resources More Sustainably?
• We can try to find substitutes for scarce resources, reduce resource waste, and recycle and reuse minerals.
• We can try to find substitutes for scarce resources, reduce resource waste, and recycle and reuse minerals.
ReclamationReclamation
• The good news: Mining now requires reclamation• Reclamation: Returning the land as close as
possible to original state.
Industrial EcosystemsIndustrial Ecosystems
• Design industrial process to mimic nature