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)

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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