Energy Energy

Drives Drives earthquakes and earthquakes and volcanic eruptionsvolcanic eruptions

Concentrated at Concentrated at certain tectonic certain tectonic settingssettings

Associated with Associated with the Earth’s the Earth’s formationformation

Driving Forces on and Driving Forces on and within the Earth?within the Earth?

Heat formation: Heat formation: – Impact of asteroids and comets in Impact of asteroids and comets in

Earth’s early historyEarth’s early history– Decay of radioactive elementsDecay of radioactive elements– Gravitational contractionGravitational contraction– Differentiation into layersDifferentiation into layers

Driving Forces within the EarthDriving Forces within the Earth

Artist Impression, NASA

Earth’s internal heatEarth’s internal heat– Flows within the mantle (largest volume Flows within the mantle (largest volume

of Earth)of Earth)– Release in terms of volcanic activity and Release in terms of volcanic activity and

earthquakesearthquakes– Long-term: continents, oceans and Long-term: continents, oceans and

atmosphereatmosphere– Movement of tectonic platesMovement of tectonic plates

Driving Forces on and within Driving Forces on and within the Earth?the Earth?

Greg Houseman, University of Leeds

GravityGravity: the attraction between : the attraction between bodiesbodies– Segregating elements within the EarthSegregating elements within the Earth– Movement along the Earth’s surfaceMovement along the Earth’s surface

landslideslandslides

– Movement within the EarthMovement within the Earth Subducting oceanic slab moving into the Subducting oceanic slab moving into the

mantlemantle

Driving Forces on the EarthDriving Forces on the Earth

Landslide, China

The SunThe Sun– ¼ of the Sun’s energy reaches the Earth¼ of the Sun’s energy reaches the Earth– Evaporation Evaporation – Warming of atmosphere and Warming of atmosphere and

hydrospherehydrosphere– Weather: movement of air from warm to Weather: movement of air from warm to

cooler areascooler areas

Driving Forces on the EarthDriving Forces on the Earth

Formation of Solar SystemFormation of Solar System

What happened in the past and how What happened in the past and how is this currently reflected?is this currently reflected?– Gravitional forceGravitional force– Variations of temperaturesVariations of temperatures– RotationRotation– Composition of materialComposition of material– Different states of matterDifferent states of matter

A nebula is formed from A nebula is formed from a collection of gases a collection of gases (98%) and dust (2%) (98%) and dust (2%)

The mass rotates and is The mass rotates and is held together by held together by gravity.gravity.

The Nebular HypothesisThe Nebular Hypothesis

The solar system formation

Where do we see this in our Where do we see this in our sky?sky?

Third star down Third star down on Orion’s belton Orion’s belt

Star nurseryStar nursery 100 light years 100 light years

across (1 light across (1 light year equals 6 year equals 6 trillion miles)trillion miles)

Reflection of dust Reflection of dust and hydrogenand hydrogen

Orion ConstellationOrion Constellation

Winter sky Winter sky constellationconstellation

Hunter in Greek Hunter in Greek mythologymythology

New stars in New stars in several hundred several hundred million yearsmillion years

Nebula: Step INebula: Step I

Nebula exists and Nebula exists and through time:through time:– Contracts causing Contracts causing

the nebula to the nebula to increase increase temperature in temperature in center and increase center and increase speed of rotationspeed of rotation

The Nebula The Nebula collapses: step collapses: step

22

The collapsed The collapsed mass forms a mass forms a proto-sun and proto-sun and disc-shape disc-shape rotating mass of rotating mass of gas and dust.gas and dust.

The Orion nebula The Orion nebula contains about 153 contains about 153 visible visible protoplanetary disksprotoplanetary disks

2-17 times larger 2-17 times larger than our solar than our solar systemsystem

Rotation increasesRotation increases Temperature increases: 1,800,000 degrees Temperature increases: 1,800,000 degrees

FahrenheitFahrenheit Fusion beginsFusion begins

Protosun

FusionFusion

What does “to fuse” mean?What does “to fuse” mean? Remember, what is the composition Remember, what is the composition

of the nebula?of the nebula? Look on the periodic tableLook on the periodic table What is the relation or difference What is the relation or difference

between Hydrogen and Helium?between Hydrogen and Helium? Can you predict what fuses?Can you predict what fuses?

FusionFusion

Hydrogen (1 proton) fuses with Hydrogen (1 proton) fuses with another Hydrogen (1 proton) = another Hydrogen (1 proton) = Helium (2 protons)Helium (2 protons)

E = mcE = mc22

E = energyE = energy m= mass (very small)m= mass (very small) c squared =speed of light c squared =speed of light

(186,000 miles/second)(186,000 miles/second)

Step 3: Sun FormsStep 3: Sun Forms

The disk is The disk is “cleared out” due “cleared out” due to the immense to the immense amount of energy amount of energy released.released.

Dust and gases Dust and gases cool, condense cool, condense and accrete and accrete forming forming planetesimals.planetesimals.

Defined orbits Defined orbits around the sunaround the sun

Earth’s internal heat from Earth’s internal heat from formation

Our Our Sun

Collapsed disk not shownCollapsed disk not shown Sun is about 5 billion Sun is about 5 billion

years oldyears old 5 billion years until a red 5 billion years until a red

giant is formedgiant is formed

Temperature Temperature differences with differences with respect from the respect from the sunsun

Terrestrial planets Terrestrial planets (closer)(closer)

Jovian or gaseous Jovian or gaseous planets (farther planets (farther away)away)

                                                                                                                                                                                                                                                                                                                                      

Step 4: Material Cools and Step 4: Material Cools and Condenses; planet Condenses; planet

formationformation

Solar SystemSolar System

The first four planets are terrestrial The first four planets are terrestrial (iron and silicate)(iron and silicate)

The last planets are composed of The last planets are composed of gasesgases

Moon’s Moon’s FormationFormation

A large size planet , A large size planet , thought to be the thought to be the size of Mars, size of Mars, collided with Earth- collided with Earth- 4.4 billion years ago4.4 billion years ago

The debris formed The debris formed the moonthe moon

The impact, set the The impact, set the Earth on its axis Earth on its axis

23 degrees23 degrees

5:20

The Earth tilted on its axis in response to the collision

The Early EarthThe Early Earth

Hot Hot HomogenousHomogenous Crust as we know it, Crust as we know it,

not developednot developed 4.6 billion years ago4.6 billion years ago Melted again due to Melted again due to

the collision of the the collision of the Mars size planetMars size planet

Transitional EarthTransitional Earth

Segregation of Segregation of elements by densityelements by density

Iron moves to the Iron moves to the centercenter

Gravitational pull Gravitational pull and rotation and rotation

Chemically distinct Chemically distinct layerslayers

Crust: oxygen and Crust: oxygen and silicon (70%)silicon (70%)

Mantle: iron, Mantle: iron, magnesium, lower % magnesium, lower % Si, OSi, O

Core: iron and nickelCore: iron and nickel

Physically Distinct LayersPhysically Distinct Layers

Inner core: solidInner core: solid Outer core: liquidOuter core: liquid Mantle: capable of Mantle: capable of

flowflow Asthenosphere: Asthenosphere:

acts like a hot acts like a hot plasticplastic

Lithosphere: rigidLithosphere: rigid

LithosphereLithosphere

Rigid layer that lies between the Rigid layer that lies between the surface and 60-100 milessurface and 60-100 miles

““Floats” on the asthenosphereFloats” on the asthenosphere The tectonic plates are composed of The tectonic plates are composed of

lithospherelithosphere

Contains crust and upper mantleContains crust and upper mantle

Lithosphere

Continental Continental CrustCrust

Less denseLess dense Higher % of silicon Higher % of silicon

and oxygenand oxygen Lower % of iron Lower % of iron

and magnesiumand magnesium Thicker (15-25 Thicker (15-25

miles)miles) 30 % of Earth’s 30 % of Earth’s

surfacesurface

Oceanic CrustOceanic Crust

More denseMore dense Higher % of iron Higher % of iron

and magnesiumand magnesium Lower % of silicon Lower % of silicon

and oxygenand oxygen Thinner (5-7 miles)Thinner (5-7 miles) 70 % of Earth’s 70 % of Earth’s

surfacesurface

AsthenosphereAsthenosphere

Relatively soft layer capable of flow Relatively soft layer capable of flow that lies below a depth of 60-100 that lies below a depth of 60-100 miles (upper mantle)miles (upper mantle)

Dr. Railsback, University of Georgia

The MantleThe Mantle

Largest portion of the EarthLargest portion of the Earth Very rich in iron and magnesiumVery rich in iron and magnesium Very poor in silicon and oxygenVery poor in silicon and oxygen The mantle is solid but because of The mantle is solid but because of

high temperatures and pressures, it high temperatures and pressures, it is soft enough to flowis soft enough to flow

The The asthenosphereasthenosphere is part of the is part of the upper mantleupper mantle

The CoreThe Core

Outer core-liquid which can flow and Outer core-liquid which can flow and generates the Earth’s magnetic generates the Earth’s magnetic fieldfield

Inner core- solid and rotates faster Inner core- solid and rotates faster than the Earththan the Earth

Mostly iron, some nickelMostly iron, some nickel

Complex fields in the core contribute to the dipole field at the surface (UC Berkeley)

The magnetic field protects The magnetic field protects the Earth from solar the Earth from solar

radiationradiation

External Source of Earth’s External Source of Earth’s WaterWater

The collision of The collision of comets with the comets with the Earth’s surfaceEarth’s surface

As the ice hits the As the ice hits the warm Earth, the ice warm Earth, the ice melts to watermelts to water

Gravity holds the Gravity holds the water to the water to the surfacesurfaceHaley’s comet contains ices

and dust. The tail is created by ice to sublimate to steam.

Water vapor is Water vapor is released during released during volcanismvolcanism

Cooling of the hot Cooling of the hot Earth involved Earth involved intense volcanismintense volcanism

Water condensesWater condenses

Internal Source of Earth’s Internal Source of Earth’s WaterWater

Formation of AtmosphereFormation of Atmosphere

Gas is expelled Gas is expelled from magma during from magma during volcanic eruptionsvolcanic eruptions

Nitrogen, carbon Nitrogen, carbon dioxide, hydrogen, dioxide, hydrogen, sulfur dioxide and sulfur dioxide and waterwater

Early Earth’s Early Earth’s atmosphere did atmosphere did not contain which not contain which gas? Why?gas? Why?

                        

        

History of the History of the EarthEarth

4.6 billion years old4.6 billion years old 4.4 bya, formation of moon4.4 bya, formation of moon 3.9 bya, oldest rock (sedimentary rock)3.9 bya, oldest rock (sedimentary rock)

– sedimentary rocks are made-up of sedimentary rocks are made-up of fragments of preexisting rocksfragments of preexisting rocks

– Sediments are carried and deposited by Sediments are carried and deposited by water and windwater and wind

– implies the existence of weather and implies the existence of weather and waterwater

4.1 bya, age of particles within the 4.1 bya, age of particles within the sedimentary rocksedimentary rock

Early Earth

3.5 bya, first bacteria3.5 bya, first bacteria 3.2 bya, algae (product?)3.2 bya, algae (product?) plantsplants

– photosynthesis, by-product is oxygenphotosynthesis, by-product is oxygen worms and jelly fishworms and jelly fish 500 million years ago, Cambrian (life) 500 million years ago, Cambrian (life)

explosion: marine fauna; modern phyla: explosion: marine fauna; modern phyla: sponges, mollusks (clams and snails), sponges, mollusks (clams and snails), echinoderms (sea urchins and stars), echinoderms (sea urchins and stars), anthropoda -trilobites(crabs, lobsters)anthropoda -trilobites(crabs, lobsters)

History of History of the Earththe Earth

Fossil Worm, Cambrian

Sponge

Trilobite

Earth as an Earth as an evolving systemevolving system

Creation and early EarthCreation and early Earth Earth’s chemically and physically Earth’s chemically and physically

distinct layersdistinct layers Atmosphere (air)Atmosphere (air) Hydrosphere (water)Hydrosphere (water) Biosphere (plants and animals)Biosphere (plants and animals)

SummarySummary

The Nebular HypothesisThe Nebular Hypothesis Earth’s heat sourcesEarth’s heat sources

– Radioactive decayRadioactive decay– Initial heat produced by collision of Initial heat produced by collision of

other objectsother objects Moon, water and gas formationMoon, water and gas formation Earth’s layers, differences and Earth’s layers, differences and

locationslocations Importance of gravitational pullImportance of gravitational pull

Think Quest