Geology and Nonrenewable Mineralschapter 14

Core Case Study: Environmental Effects of Gold Mining

Gold producers• South Africa• Australia• United States• Canada

Cyanide heap leaching- controversial• Extremely toxic to birds and mammals• Ponds can leak or overflow• 2000: Collapse of a dam retaining a cyanide

leach pond• Impact on organisms and the environment

Gold Mine with Cyanide Leach Piles and Ponds in South Dakota, U.S.

GOLD IN GEORGIA

Has been found in 37 counties 1829-1933 The gold rush started near

Dahlonega. By 1940, gold was harder to find and many miners left for California

14-1 What Are the Earth’s Major Geological Processes and Hazards?

Concept 14-1A Gigantic plates in the earth’s crust move very slowly atop the planet’s mantle, and wind and water move the matter from place to place across the earth’s surface.

Concept 14-1B Natural geological hazards such as earthquakes, tsunamis, volcanoes, and landslides can cause considerable damage.

The Earth Is a Dynamic Planet

What is geology? (dynamic processes that occur on the Earth’s surface and in its interior)

http://ngm.nationalgeographic.com/video/player#/?titleID=how-big-is-7billion

Three major concentric zones of the earth• Core – solid inner core and liquid outer core• Mantle• Including the asthenosphere – partly melted rock

that flows

• Crust• Continental crust• Oceanic crust: 71% of crust

Planet Earth: Lithosphere

Lithosphere - Earth’s crust and upper mantle Thickness varies from 10 to 200 km1. Oceanic crust – floor of deep ocean basins

- Composed of basalt (igneous). Also iron, magnesium and calcium.

- Thin (4-5 km) and young. 2. Continental crust -- forms continents.

- Composed of granite (igneous). Also silicon, aluminum, sodium and potassium.

- Thickness 35 to 70 km. - Old crust.

The Lithosphere

The crust and the upper layer of the mantle together make up a zone of rigid, brittle rock called the Lithosphere.

The Crust

The crust is composed of two rocks. The continental crust is mostly granite. The oceanic crust is basalt. Basalt is much denser than the granite. Because of this, the less dense continents ride on the denser oceanic plates.

The Mantle

The Mantle is the largest layer of the Earth. The middle mantle is composed of very hot dense rock that flows like asphalt under a heavy weight. The movement of the middle mantle (asthenosphere) is the reason that the crustal plates of the Earth move.

Convection Currents

The middle mantle "flows" because of convection currents. Convection currents are caused by the very hot material at the deepest part of the mantle rising, then cooling and sinking again --repeating this cycle over and over.

Convection Currents

The next time you heat anything like soup or water in a pan you can watch the convection currents move in the liquid. When the convection currents flow in the asthenosphere they also move the crust. The crust gets a free ride with these currents, like the cork in this illustration.

The Outer Core

The core of the Earth is like a ball of very hot metals. The outer core is so hot that the metals in it are all in the liquid state. The outer core is composed of the melted metals of nickel and iron.

The Inner Core

The inner core of the Earth has temperatures and pressures so great that the metals are squeezed together and are not able to move about like a liquid, but are forced to vibrate in place like a solid. (Ni, Fe, Au, Pt and U)

Let’s Review!• What are the 3 concentric zones of the

earth?

• CRUST, MANTLE AND CORE

• What is the main rock that comprises the continental crust?

• GRANITE

• What is the main rock that comprises the oceanic crust?

• BASALT

• The crust and upper mantle make up the _____.

• LITHOSPHERE

• What makes the crustal plates move?

• CONVECTION CURRENTS

• The layer of the mantle that flows and is responsible for these convection currents is the _____.

• ASTHENOSPHERE

Fig. 14-2, p. 346

Volcanoes Folded mountain beltAbyssal

floorOceanic

ridgeAbyssal

floor Trench Abyssal plain

Abyssal hills Craton

Oceanic crust (lithosphere)

Aby

ssal

pla

in

Continental shelf Continental

slopeContinental rise Mantle

(lithosphere) Continental crust (lithosphere)

Mantle (lithosphere)

Mantle (asthenosphere)

The Earth Beneath Your Feet Is Moving (2) Three types of boundaries between plates• Divergent plates • Oceanic ridge and continental rift valleys• EX: Mid-Atlantic Ridge, East Pacific Rise, East

African Great Rift Valley• Convergent plates• Subduction, subduction zone• Trench• EX: Cascade Mt Range (Ca to Wa- Mt. St.

Helens)• Transform faults

• Sliding of plates past each other• EX: San Andreas Fault

Fig. 14-3, p. 346

Spreading center

Ocean trench

Plate movement

Subduction zone Oceanic crust Oceanic crust

Continental crust

Continental crust

Material cools as it reaches

the outer mantle

Cold dense material falls back through

mantle

Hot material rising

through the mantle

Mantle convection

cell

Two plates move towards each other. One is subducted back into the mantle on a falling convection current.

Mantle

Hot outer core Inner

core

Plate movement

Fig. 14-4, p. 347

EURASIAN PLATE

NORTH AMERICAN PLATE

ANATOLIAN PLATE

JUAN DE FUCA PLATE

CARIBBEAN PLATE

PHILIPPINE PLATE

CHINA SUBPLATE

AFRICAN PLATE

ARABIAN PLATE INDIA

PLATEPACIFIC PLATE

PACIFIC PLATECOCOS

PLATESOUTH AMERICAN PLATE

NAZCA PLATE AUSTRALIAN

PLATESOMALIAN SUBPLATE

SCOTIA PLATE ANTARCTIC PLATE

Transform faultsDivergent plate boundaries Convergent plate boundaries

PLATES

• Move at about the rate a fingernail grows• Mountains, earthquakes and volcanoes

occur at plate boundaries• Divergent- ridges in ocean/rifts on land• Convergent- subduction/trenches in oceans

and mountains (orogonic belt) on land • Transform fault- 2 plates slide past one

another (San Andreas Fault)

The San Andreas Fault as It Crosses Part of the Carrizo Plain in California, U.S.

Mount Everest Base Camp

Himalayas

Khumbu Icefall

Mount Everest

Mt Everest- tallest mountain on land (29,029 ft = 8848 m) 1.6-3.9 (4-10 cm) inches higher every year

Everest is part of the Himalaya mountain range along the border of Nepal and Tibet.

At 9,800 feet, for example, there's about 2/3 of the oxygen in the air than at sea level. At 20,000 ft, there is roughly half the oxygen content in the air. At 29,035ft, the summit of Everest, there is only a third of the oxygen in the air.

At the summit, the temperature can be 100°F below zero. But on a good summit day, a climber can expect around -15°F

On May 29, 1953, Tenzing

Norgay Sherpa of Nepal &

Edmund Percival Hillary of

New Zealand climbed to

the summit of Everest via

the Southeast Ridge Route

http://www.youtube.com/watch?feature=endscreen&NR=1&v=56nWTyDTLZc

Divergent boundaries Africa’s Great Rift Valley

The oceanic ridge is a continuous submarine mountain chain extending approximately 80,000 km (50,000 miles) through all the world’s oceans

Some Parts of the Earth’s Surface Build Up and Some Wear Down

Internal geologic processes • Generally build up the earth’s surface

External geologic processes (driven by the sun and influenced by gravity)• Weathering (key in soil formation)• Physical, Chemical, and Biological processes that

break down rock• Erosion• Wind• Flowing water• Human activities• Glaciers- (formed the Great Lakes)

Fig. 14-6, p. 348

Parent material (rock)

Biological weathering (tree roots and lichens)

Chemical weathering (water, acids, and gases)

Physical weathering (wind, rain, thermal expansion and contraction, water freezing)

Particles of parent material

Volcanoes Release Molten Rock from the Earth’s Interior

Volcano • Fissure- vent or crack• Magma• Lava

1980: Eruption of Mount St. Helens (Mount Pinatubo)

1991: Eruption of Mount Pinatubo- Philippines

Benefits of volcanic activity- forms mountains, lakes (Crater Lake, OR), fertile soils

Fig. 14-7, p. 349

Extinct volcanoes

Eruption cloud

AshAsh flow

Lava flow

Mud flow

Landslide Central vent

Magma conduit

Magma reservoir

Solid

lithosphere

Upwelling

magmaPartially molten

asthenosphere

Acid rain

Earthquakes Are Geological Rock-and-Roll Events (1)

Earthquake• Seismic waves- vibrations caused by

earthquakes• Focus • Epicenter• Magnitude – amount of energy released• Amplitude – size of seismic waves

Earthquakes Are Geological Rock-and-Roll Events (2)

Richter scale – a logarithmic scale recorded by a seismograph. Measures the amplitudes of the waves produced. An earthquake of magnitude 5 has 10X more ground shaking than a magnitude of 4. It is the energy though that knocks down buildings and causes damage. A magnitude of 5 releases 32X more energy than a magnitude 4 eq.• 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

Earthquakes Are Geological Rock-and-Roll Events (3) Foreshocks and aftershocksForeshocks and aftershocks http://earthquake.usgs.gov/learn/animations/animation.php?

flash_title=Foreshocks%2C+Mainshocks%2C+and+Aftershocks+Flash+Animation&flash_file=aftershock&flash_width=400&flash_height=275

Primary effects of earthquakesPrimary effects of earthquakes

Due to the shaking and the resulting damage to buildings/infrastructure and due to loss of life or injury, land displacement

Secondary effectsSecondary effects

Rock slides, flooding, liquefaction of sediments, fires, and tsunamis

Reduce damageReduce damage by mapping faults, strengthening building codes, preparing emergency teams, storing supplies and educating the public

Fig. 14-8, p. 350

Liquefaction of recent sediments causes buildings to sink

Two adjoining plates move laterally along the fault line

Earth movements cause flooding in low-lying areas

Landslides may occur on hilly ground

Shock waves

EpicenterFocus

Areas of Greatest Earthquake Risk in the United States

Areas of Greatest Earthquake Risk in the World

EQ TRIVIA!

There are over 1 million eq a year There are over 10,000 eq in California a year. San Andreas Fault is over 800 miles long.

Earthquakes on the Ocean Floor Can Cause Huge Waves Called Tsunamis

Tsunami, tidal waveTsunami, tidal wave Can travel as fast as a jet plane Detection of tsunamisDetection of tsunamis

buoys, pressure recorder December 26, 2004: Indian Ocean tsunamiDecember 26, 2004: Indian Ocean tsunami• Magnitude of 9.15 earthquake• Waves as high as 100 feet, 228,000 were killed• Coral reefs and mangrove forests reduce wave

impact. (mangrove forests had been cleared and many reefs have been damaged in last 30 years)

Shore near Gleebruk in Indonesia before and after the Tsunami on June 23, 2004

http://www.youtube.com/watch?feature=player_embedded&v=tUN_UTY0GNo#!

Fig. 14-11, p. 352

Earthquake in seafloor swiftly pushes water upwards, and starts a series of waves

Waves move rapidly in deep ocean reaching speeds of up to 890 kilometers per hour.

As the waves near land they slow to about 45 kilometers per hour but are squeezed upwards and increased in height.

Waves head inland causing damage in their path.

Undersea thrust fault

Upward waveBangladesh

India

Thailand

Sri Lanka MalaysiaEarthquake

SumatraIndonesia

December 26, 2004, tsunami

Burma

Gravity and Earthquakes Can Cause Landslides

Mass wasting • Slow movement or• Fast movement • Rockslides• Avalanches• Mudslides • 1970, earthquake in Peru caused massive

landslide that killed 17,000 people

Effect of human activities such as forest clearing, road building and crop growing increases the frequency of and damage caused

What do you remember??

What mountains were formed at a convergent boundary?

CASCADES AND HIMALAYAS How were the Hawaiian Islands formed BY A HOT SPOT Name a feature at a divergent boundary AFRICAN RIFT VALLEY, OCEANIC RIDGE Name a famous transform fault SAN ANDREAS FAULT

How are earthquakes recorded? RICHTER SCALE What is the tallest mountain on land? MOUNT EVEREST Name 3 factors of erosion WIND, WATER, GLACIERS AND HUMAN

ACTIVITIES

Study the following website. For site #3, take the quiz, save it as a word document, and send it to me through edmodo.

http://www.geo.cornell.edu/hawaii/220/PRI/continental_puzzle.html

http://www.wwnorton.com/college/geo/egeo2/content/animations/2_6.htm (hotspots)

www.learner.org/interactives/dynamicearth/index.html

14-2 How Are the Earth’s Rocks Recycled?

Concept 14-2 The three major types of rocks found in the earth’s crust—sedimentary, igneous, and metamorphic—are recycled very slowly by the process of erosion, melting, and metamorphism.