Earth’s InteriorEarth’s Interior

p. 124-131p. 124-131

Chapter 5.1Chapter 5.1

Exploring inside the EarthExploring inside the Earth

Since we cannot travel deep inside the Since we cannot travel deep inside the Earth scientist use evidence to learn about Earth scientist use evidence to learn about the Earth interiorthe Earth interior

1. Direct evidence from rock samples1. Direct evidence from rock samples

Deepest mine: 3.8 kilometers or 6.1 Deepest mine: 3.8 kilometers or 6.1 miles miles

Deepest hole dug: 12 km or 19 milesDeepest hole dug: 12 km or 19 miles

2. Indirect evidence from seismic waves2. Indirect evidence from seismic waves

Earthquake waves speed and pathEarthquake waves speed and path

2 main layers inside Earth2 main layers inside Earth

1. Crust1. Crust 2. Mantle2. Mantle CoreCore All vary greatly in temperature, size, All vary greatly in temperature, size,

composition, and texturecomposition, and texture

TemperatureTemperature

Temperature- at 20 meters down you Temperature- at 20 meters down you begin to feel warmth. begin to feel warmth.

After that every 40 meters down you After that every 40 meters down you go the temperature increase 1go the temperature increase 1°° C. C.

The heat is from the formation of The heat is from the formation of planet and radioactive materials in planet and radioactive materials in the Earth.the Earth.

PressurePressure Increasing Depth = Increasing Increasing Depth = Increasing

PressurePressure

CrustCrust

Outermost layerOutermost layer Includes dry land and the ocean floorIncludes dry land and the ocean floor It is thickest under high mountains(up to It is thickest under high mountains(up to

70 km) and thinnest under the ocean(5 70 km) and thinnest under the ocean(5 km) km)

The average is 40 km thickThe average is 40 km thick Crust under ocean is called oceanic crust Crust under ocean is called oceanic crust

(mostly basaltic rock-heavier)(mostly basaltic rock-heavier) Land crust is called continental crust Land crust is called continental crust

(mostly granitic rock-lighter)(mostly granitic rock-lighter)

MantleMantle

At about 40 km down you cross a At about 40 km down you cross a boundary into the mantle. It is boundary into the mantle. It is divided into 3 very hot layers which divided into 3 very hot layers which together are about 3000 km thick.together are about 3000 km thick.

LithosphereLithosphere AsthenosphereAsthenosphere Lower mantleLower mantle

LithosphereLithosphere Uppermost layerUppermost layer Lithosphere is crust and uppermost Lithosphere is crust and uppermost

mantle together.mantle together. ““Lithos”Lithos” means “stone” in Greek and means “stone” in Greek and

averages about 100 km thick.averages about 100 km thick. Very rigidVery rigid

AsthenosphereAsthenosphere

Less rigidLess rigid Like road tar in the sun it is soft, Like road tar in the sun it is soft,

plastic-like and very bendable.plastic-like and very bendable. ““Asthenes”Asthenes” in Greek means “weak” in Greek means “weak” Still SolidStill Solid

The Lower MantleThe Lower Mantle

Beneath the asthenosphere, the Beneath the asthenosphere, the mantle is solid.mantle is solid.

Goes all the way to the core.Goes all the way to the core.

The COREThe CORE

Made of iron and nickelMade of iron and nickel 2 parts2 parts Liquid outer coreLiquid outer core Solid inner core-squeezed so tightly Solid inner core-squeezed so tightly

the atoms cannot spread apart to be the atoms cannot spread apart to be liquidsliquids

May also contain: oxygen, silicon, May also contain: oxygen, silicon, and sulfurand sulfur

Together about 3486 km thickTogether about 3486 km thick

Magnetic FieldMagnetic Field

Movement in the liquid outer core Movement in the liquid outer core forms the magnetic field for the forms the magnetic field for the Earth. Earth.

This produces a protective shield This produces a protective shield around the Earth and the whole around the Earth and the whole planet acts as a bar magnet. planet acts as a bar magnet.

This means we have a north and This means we have a north and south pole.south pole.

Over the course of history, the poles Over the course of history, the poles will actually switchwill actually switch

Convection and the Convection and the MantleMantle

p. 132-135p. 132-135

5.25.2

HeatHeat

Heat is energy in motion. This means Heat is energy in motion. This means the warmer the object the faster the the warmer the object the faster the particles are moving or the more particles are moving or the more energy they have.energy they have.

Heat always is transferred from Heat always is transferred from warm to cool.warm to cool.

When you open the door in the When you open the door in the winter, are you letting the cold air in winter, are you letting the cold air in or the warm air out?or the warm air out?

Types of Heat TransferTypes of Heat Transfer

Three types of heat transfer:Three types of heat transfer: Radiation, convection, conductionRadiation, convection, conduction

RadiationRadiation

Transfer of energy through space Transfer of energy through space with no direct contact between the with no direct contact between the heat source and the object.heat source and the object.

Examples: energy from the sun, Examples: energy from the sun, flame, fireflame, fire

ConductionConduction

Heat transfer between objects in Heat transfer between objects in direct contact with one another. They direct contact with one another. They must be touching.must be touching.

Example: touching a hot stove, Example: touching a hot stove, cooking on the stove, etc.cooking on the stove, etc.

ConvectionConvection

Heat transfer by a movement of fluids Heat transfer by a movement of fluids (liquid or gas)(liquid or gas)

Differences in temp and density can Differences in temp and density can cause convection.cause convection.

When something is heated the When something is heated the particles move fast and require MORE particles move fast and require MORE space, so they spread out. This cause space, so they spread out. This cause the density to decrease.the density to decrease.

Cooler objects are closer and more Cooler objects are closer and more dense.dense.

Convection currentsConvection currents Is the flow that Is the flow that

transfers heat in a transfers heat in a fluidfluid

Heat rises and cool Heat rises and cool sinks.sinks.

This continues as This continues as long as heat is long as heat is added.added.

Also occurs in airAlso occurs in air Have you ever Have you ever

looked at the looked at the pavement on a hot pavement on a hot summer day?summer day?

Convection Currents in EarthConvection Currents in Earth Heat from the core and the mantle Heat from the core and the mantle

causes convection currents in the causes convection currents in the mantle.mantle.

Drifting ContinentsDrifting Continents

5.35.3

p. 136-140p. 136-140

Continental DriftContinental Drift

Early in the 1800’s when the first Early in the 1800’s when the first complete maps on the Earth’s complete maps on the Earth’s surface were being made showing all surface were being made showing all the continents, something was the continents, something was noticed. The edges of the continents noticed. The edges of the continents looked as if they could fit together looked as if they could fit together like puzzle pieces.like puzzle pieces.

Alfred Wegener thought that was no Alfred Wegener thought that was no coincidence, and wrote the theory that all coincidence, and wrote the theory that all the continents were once joined together the continents were once joined together and had drifted apart. He called this theory and had drifted apart. He called this theory the continental drift theory. the continental drift theory.

He believed that 300 million years ago all He believed that 300 million years ago all the continents were together and they the continents were together and they began to move horizontally apart. He called began to move horizontally apart. He called the large landmass containing all the the large landmass containing all the continents Pangaea, which means “All continents Pangaea, which means “All Land.”Land.”

Evidence to back up the theoryEvidence to back up the theory

Wegener gathered evidence to Wegener gathered evidence to support his theory.support his theory.

He used land features, fossils, and He used land features, fossils, and climate change.climate change.

In 1915, he published In 1915, he published The Origin of The Origin of Continents and oceans.Continents and oceans.

Land Feature EvidenceLand Feature Evidence

Mountain ranges lined up on different Mountain ranges lined up on different continents South America and Africa.continents South America and Africa.

Coal fields in Europe and North Coal fields in Europe and North America lined up.America lined up.

Fossil EvidenceFossil Evidence

Glossopteris Glossopteris is a fern fossil that has been is a fern fossil that has been found on several continents: africa, South found on several continents: africa, South america, Australia, Asia(India) and america, Australia, Asia(India) and Antartica. Based on climate now: Some of Antartica. Based on climate now: Some of these ferns could not have grown there, these ferns could not have grown there, also plants could not have traveled across also plants could not have traveled across oceans.oceans.

Other fossils of fresh water reptiles had Other fossils of fresh water reptiles had been found across oceans and they could been found across oceans and they could not have swum those great distances.not have swum those great distances.

Climate evidenceClimate evidence

Climate changes as a continent Climate changes as a continent moves but the fossils there remain.moves but the fossils there remain.

Tropical plant fossils have been Tropical plant fossils have been found in the Arctic Circle.found in the Arctic Circle.

Glacier evidence was found in South Glacier evidence was found in South Africa where it is very warm now.Africa where it is very warm now.

Wegener’s theory rejectedWegener’s theory rejected

Though some believed him when he Though some believed him when he was alive, most accepted his theory was alive, most accepted his theory after more evidence was discovered after more evidence was discovered after his death in 1930.after his death in 1930.

It was not widely accepted because It was not widely accepted because he lacked evidence as to HOW the he lacked evidence as to HOW the continents moved.continents moved.