op ch02 lecture_earth3

Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 2: Journey to the Center of the Earth

Chapter 2Journey to the Center of the Earth

©2008 W. W. Norton & Company, Inc.

Portrait of a PlanetThird Edition

earthearth

LECTURE OUTLINE

Journey to the Center of the EarthJourney to the Center of the Earth

Prepared by

Ronald ParkerEarlham College Department of Geosciences

Richmond, Indiana

Prepared by

Ronald ParkerEarlham College Department of Geosciences

Richmond, Indiana


Earth’s SurfaceEarth’s SurfaceEarth’s SurfaceEarth’s Surface Our experience with Earth is limited to its surface.Our experience with Earth is limited to its surface. Yet Earth has a complicated interior. Yet Earth has a complicated interior. Earth is characterized by…Earth is characterized by…

An internally generated magnetic field.An internally generated magnetic field. Solid and liquid surfaces.Solid and liquid surfaces. A gaseous envelope.A gaseous envelope. A layered interior.A layered interior.

Our experience with Earth is limited to its surface.Our experience with Earth is limited to its surface. Yet Earth has a complicated interior. Yet Earth has a complicated interior. Earth is characterized by…Earth is characterized by…

An internally generated magnetic field.An internally generated magnetic field. Solid and liquid surfaces.Solid and liquid surfaces. A gaseous envelope.A gaseous envelope. A layered interior.A layered interior.


The Solar System The Solar System The Solar System The Solar System Human perceptions have changed. Human perceptions have changed.

Early history – Planets as moving lights.Early history – Planets as moving lights. 1600s – 11600s – 1stst telescopes saw hazy spheres. telescopes saw hazy spheres. Today – A complex, evolving system. Today – A complex, evolving system.

Structure Structure HistoryHistory

Space probes have photographed Space probes have photographed and analyzed planets. and analyzed planets.

Scientists have hypothesized likely Scientists have hypothesized likely origins of the solar system. origins of the solar system.

Human perceptions have changed. Human perceptions have changed. Early history – Planets as moving lights.Early history – Planets as moving lights. 1600s – 11600s – 1stst telescopes saw hazy spheres. telescopes saw hazy spheres. Today – A complex, evolving system. Today – A complex, evolving system.

Structure Structure HistoryHistory

Space probes have photographed Space probes have photographed and analyzed planets. and analyzed planets.

Scientists have hypothesized likely Scientists have hypothesized likely origins of the solar system. origins of the solar system.


Earth and the Solar System Earth and the Solar System Earth and the Solar System Earth and the Solar System What would solar system visitors notice? What would solar system visitors notice?

Magnetic field.Magnetic field. Atmosphere.Atmosphere. Surface features.Surface features.

Continents.Continents.Oceans.Oceans.Polar ice caps.Polar ice caps.Evidence of humanity? Evidence of humanity?

Structures.Structures.Dams.Dams.Great Wall of China.Great Wall of China.Cities.Cities.Roads / canals.Roads / canals.

Electric lights.Electric lights.

What would solar system visitors notice? What would solar system visitors notice? Magnetic field.Magnetic field. Atmosphere.Atmosphere. Surface features.Surface features.

Continents.Continents.Oceans.Oceans.Polar ice caps.Polar ice caps.Evidence of humanity? Evidence of humanity?

Structures.Structures.Dams.Dams.Great Wall of China.Great Wall of China.Cities.Cities.Roads / canals.Roads / canals.

Electric lights.Electric lights.


The Celestial Neighborhood The Celestial Neighborhood The Celestial Neighborhood The Celestial Neighborhood Interstellar space: a vacuum with a virtual absence of matter. Interstellar space: a vacuum with a virtual absence of matter. The amount of matter greatly increases approaching the Sun. The amount of matter greatly increases approaching the Sun. The Sun ejects matter outward into space as the solar wind.The Sun ejects matter outward into space as the solar wind.

Interstellar space: a vacuum with a virtual absence of matter. Interstellar space: a vacuum with a virtual absence of matter. The amount of matter greatly increases approaching the Sun. The amount of matter greatly increases approaching the Sun. The Sun ejects matter outward into space as the solar wind.The Sun ejects matter outward into space as the solar wind. Solar wind:Solar wind:

Magnetically charged particles.Magnetically charged particles. Stream outward in all directions. Stream outward in all directions. Consists of…Consists of…

Protons (+ charge).Protons (+ charge).Electrons (– charge).Electrons (– charge).

A small percentage of the solar A small percentage of the solar wind impinges upon Earth. wind impinges upon Earth.

Solar wind:Solar wind: Magnetically charged particles.Magnetically charged particles. Stream outward in all directions. Stream outward in all directions. Consists of…Consists of…

Protons (+ charge).Protons (+ charge).Electrons (– charge).Electrons (– charge).

A small percentage of the solar A small percentage of the solar wind impinges upon Earth. wind impinges upon Earth.


Magnetic FieldMagnetic FieldMagnetic FieldMagnetic Field The Earth has a prominent dipolar magnetic field.The Earth has a prominent dipolar magnetic field. Like a bar magnet, the field has north and south ends. Like a bar magnet, the field has north and south ends. Magnetic flux has a direction that flows N to S.Magnetic flux has a direction that flows N to S.

The Earth has a prominent dipolar magnetic field.The Earth has a prominent dipolar magnetic field. Like a bar magnet, the field has north and south ends. Like a bar magnet, the field has north and south ends. Magnetic flux has a direction that flows N to S.Magnetic flux has a direction that flows N to S. Magnetic field lines…Magnetic field lines…

Extend into space.Extend into space. Weaken with distance.Weaken with distance. Create a shield around Create a shield around

Earth (the magnetosphere).Earth (the magnetosphere).

Magnetic field lines…Magnetic field lines… Extend into space.Extend into space. Weaken with distance.Weaken with distance. Create a shield around Create a shield around

Earth (the magnetosphere).Earth (the magnetosphere).


The Van Allen BeltsThe Van Allen Belts The solar wind is deflected by the magnetosphere. Near the Earth, the stronger magnetic field forms the Van

Allen belts, which arrest deadly cosmic radiation.

The solar wind is deflected by the magnetosphere. Near the Earth, the stronger magnetic field forms the Van

Allen belts, which arrest deadly cosmic radiation.



AuroraeAuroraeAuroraeAurorae Some ions escape Van Allen belts.Some ions escape Van Allen belts.

These ions are pulled to the magnetic poles.These ions are pulled to the magnetic poles. The ions create light in the upper atmosphere.The ions create light in the upper atmosphere.

Spectacular aurora follow solar flares.Spectacular aurora follow solar flares. Aurora borealis – Northern lights.Aurora borealis – Northern lights. Aurora australis – Southern lights. Aurora australis – Southern lights.

Some ions escape Van Allen belts.Some ions escape Van Allen belts. These ions are pulled to the magnetic poles.These ions are pulled to the magnetic poles. The ions create light in the upper atmosphere.The ions create light in the upper atmosphere.

Spectacular aurora follow solar flares.Spectacular aurora follow solar flares. Aurora borealis – Northern lights.Aurora borealis – Northern lights. Aurora australis – Southern lights. Aurora australis – Southern lights.


The AtmosphereThe AtmosphereThe AtmosphereThe Atmosphere Earth has a well developed atmosphere. Earth has a well developed atmosphere. Thus, Earth is unique among the terrestrial planets.Thus, Earth is unique among the terrestrial planets. Densest at sea-level, the atmosphere thins upward.Densest at sea-level, the atmosphere thins upward.

Earth has a well developed atmosphere. Earth has a well developed atmosphere. Thus, Earth is unique among the terrestrial planets.Thus, Earth is unique among the terrestrial planets. Densest at sea-level, the atmosphere thins upward.Densest at sea-level, the atmosphere thins upward.


The atmosphere is mostly nitrogen.The atmosphere is mostly nitrogen. Oxygen was absent from the atmosphere before 2.5 Ga.Oxygen was absent from the atmosphere before 2.5 Ga.

Other gases include:Other gases include:

The atmosphere is mostly nitrogen.The atmosphere is mostly nitrogen. Oxygen was absent from the atmosphere before 2.5 Ga.Oxygen was absent from the atmosphere before 2.5 Ga.

Other gases include:Other gases include:

The AtmosphereThe AtmosphereThe AtmosphereThe Atmosphere

Argon (Ar)Argon (Ar) Carbon dioxide (COCarbon dioxide (CO22))

Carbon monoxide (CO)Carbon monoxide (CO) Methane (CHMethane (CH44))

Neon (Ne)Neon (Ne) Ozone (OOzone (O33))

Sulfur dioxide (SOSulfur dioxide (SO22)) Chlorofluorocarbons (CFCs)Chlorofluorocarbons (CFCs)


The AtmosphereThe AtmosphereThe AtmosphereThe Atmosphere 99% of atmosphere is below 50 km, 99% of atmosphere is below 50 km,

the rest is between 50 and 500 km.the rest is between 50 and 500 km. The atmosphere is layered.The atmosphere is layered.

Troposphere (0-11 km).Troposphere (0-11 km).Mixing layer.Mixing layer.Weather is limited to this layer.Weather is limited to this layer.

Tropopause (11-12 km).Tropopause (11-12 km). Stratosphere (12-30 km).Stratosphere (12-30 km).

Sea-level atmospheric pressure.Sea-level atmospheric pressure. 14.7 pounds per square inch (psi).14.7 pounds per square inch (psi). 1.0 bar.1.0 bar.

99% of atmosphere is below 50 km, 99% of atmosphere is below 50 km, the rest is between 50 and 500 km.the rest is between 50 and 500 km.

The atmosphere is layered.The atmosphere is layered. Troposphere (0-11 km).Troposphere (0-11 km).

Mixing layer.Mixing layer.Weather is limited to this layer.Weather is limited to this layer.

Tropopause (11-12 km).Tropopause (11-12 km). Stratosphere (12-30 km).Stratosphere (12-30 km).

Sea-level atmospheric pressure.Sea-level atmospheric pressure. 14.7 pounds per square inch (psi).14.7 pounds per square inch (psi). 1.0 bar.1.0 bar.


Surface FeaturesSurface FeaturesSurface FeaturesSurface Features Earth’s surface is dominated by water and land. Earth’s surface is dominated by water and land. Water is a part of the hydrosphere.Water is a part of the hydrosphere.

Surface waterSurface water Ground water.Ground water. Glacial ice. Glacial ice.

Impact craters occur rarely on Earth.Impact craters occur rarely on Earth. Removed by weathering and erosion.Removed by weathering and erosion. Unlike other planets in the solar system.Unlike other planets in the solar system.

Earth’s surface is dominated by water and land. Earth’s surface is dominated by water and land. Water is a part of the hydrosphere.Water is a part of the hydrosphere.

Surface waterSurface water Ground water.Ground water. Glacial ice. Glacial ice.

Impact craters occur rarely on Earth.Impact craters occur rarely on Earth. Removed by weathering and erosion.Removed by weathering and erosion. Unlike other planets in the solar system.Unlike other planets in the solar system.


Surface FeaturesSurface FeaturesSurface FeaturesSurface Features Earth’s surface reveals high continents and low ocean basins. Earth’s surface reveals high continents and low ocean basins.

Position due to the differing buoyancy of each type of crust.Position due to the differing buoyancy of each type of crust.

Earth’s surface reveals high continents and low ocean basins. Earth’s surface reveals high continents and low ocean basins.

Position due to the differing buoyancy of each type of crust.Position due to the differing buoyancy of each type of crust.


Hypsometric CurveHypsometric CurveHypsometric CurveHypsometric Curve Most land lies within 1 km of sea level.Most land lies within 1 km of sea level. Most ocean floors are close to 5 km depth.Most ocean floors are close to 5 km depth. Extremes of depth or height are rare.Extremes of depth or height are rare.

Most land lies within 1 km of sea level.Most land lies within 1 km of sea level. Most ocean floors are close to 5 km depth.Most ocean floors are close to 5 km depth. Extremes of depth or height are rare.Extremes of depth or height are rare.

The 2 dominant The 2 dominant “levels” reflect “levels” reflect continental vs. continental vs. oceanic crust. oceanic crust.

The 2 dominant The 2 dominant “levels” reflect “levels” reflect continental vs. continental vs. oceanic crust. oceanic crust.


Elemental CompositionElemental CompositionElemental CompositionElemental Composition ~Ninety percent of Earth is comprised of 4 elements. ~Ninety percent of Earth is comprised of 4 elements.

Iron (Fe) ~35%Iron (Fe) ~35% Oxygen (O) ~30%Oxygen (O) ~30% Silicon (Si) ~15%Silicon (Si) ~15% Magnesium (Mg) ~10% Magnesium (Mg) ~10%

The remaining 88 naturallyThe remaining 88 naturally

occurring elements?occurring elements? Form ~10% of Earth. Form ~10% of Earth.

~Ninety percent of Earth is comprised of 4 elements. ~Ninety percent of Earth is comprised of 4 elements. Iron (Fe) ~35%Iron (Fe) ~35% Oxygen (O) ~30%Oxygen (O) ~30% Silicon (Si) ~15%Silicon (Si) ~15% Magnesium (Mg) ~10% Magnesium (Mg) ~10%

The remaining 88 naturallyThe remaining 88 naturally

occurring elements?occurring elements? Form ~10% of Earth. Form ~10% of Earth.


Earth MaterialsEarth MaterialsEarth MaterialsEarth Materials Elements combine in a variety of Earth materials. Elements combine in a variety of Earth materials.

Organic compounds – Carbon-containing compounds.Organic compounds – Carbon-containing compounds.Most are residue from once-living creatures.Most are residue from once-living creatures.Include wood, peat, lignite, coal, and oil. Include wood, peat, lignite, coal, and oil. Geologically rare (decomposes in contact with oxygen).Geologically rare (decomposes in contact with oxygen).

Elements combine in a variety of Earth materials. Elements combine in a variety of Earth materials. Organic compounds – Carbon-containing compounds.Organic compounds – Carbon-containing compounds.

Most are residue from once-living creatures.Most are residue from once-living creatures.Include wood, peat, lignite, coal, and oil. Include wood, peat, lignite, coal, and oil. Geologically rare (decomposes in contact with oxygen).Geologically rare (decomposes in contact with oxygen).


Earth MaterialsEarth MaterialsEarth MaterialsEarth Materials Elements combine in a variety of Earth materials. Elements combine in a variety of Earth materials.

Minerals – Inorganic crystalline solids. Minerals – Inorganic crystalline solids. Comprise rocks and, hence, most of the Earth.Comprise rocks and, hence, most of the Earth.Most rocks on Earth are silicates (based on Si and O).Most rocks on Earth are silicates (based on Si and O).

Glasses – Non-crystalline mineral-like matter. Glasses – Non-crystalline mineral-like matter. Rocks – Aggregates of minerals. There are many types.Rocks – Aggregates of minerals. There are many types.

Igneous – Cooled from a liquid (melt).Igneous – Cooled from a liquid (melt).Sedimentary – Debris cemented from pre-existing rock. Sedimentary – Debris cemented from pre-existing rock. Metamorphic – Rock altered by pressure and temperature. Metamorphic – Rock altered by pressure and temperature.

Elements combine in a variety of Earth materials. Elements combine in a variety of Earth materials. Minerals – Inorganic crystalline solids. Minerals – Inorganic crystalline solids.

Comprise rocks and, hence, most of the Earth.Comprise rocks and, hence, most of the Earth.Most rocks on Earth are silicates (based on Si and O).Most rocks on Earth are silicates (based on Si and O).

Glasses – Non-crystalline mineral-like matter. Glasses – Non-crystalline mineral-like matter. Rocks – Aggregates of minerals. There are many types.Rocks – Aggregates of minerals. There are many types.

Igneous – Cooled from a liquid (melt).Igneous – Cooled from a liquid (melt).Sedimentary – Debris cemented from pre-existing rock. Sedimentary – Debris cemented from pre-existing rock. Metamorphic – Rock altered by pressure and temperature. Metamorphic – Rock altered by pressure and temperature.


Earth MaterialsEarth MaterialsEarth MaterialsEarth Materials Metals – Solids made of metallic elements.Metals – Solids made of metallic elements. Melts – Rocks that have been heated to a liquid. Melts – Rocks that have been heated to a liquid.

Magma – Molten rock beneath the surface.Magma – Molten rock beneath the surface. Lava – Molten rock at the surface.Lava – Molten rock at the surface.

Volatiles – Materials that turn into gas at the surface. Volatiles – Materials that turn into gas at the surface. HH22O, COO, CO22,, CHCH44,, and SOand SO22

Volatiles are released from volcanic eruption. Volatiles are released from volcanic eruption.

Metals – Solids made of metallic elements.Metals – Solids made of metallic elements. Melts – Rocks that have been heated to a liquid. Melts – Rocks that have been heated to a liquid.

Magma – Molten rock beneath the surface.Magma – Molten rock beneath the surface. Lava – Molten rock at the surface.Lava – Molten rock at the surface.

Volatiles – Materials that turn into gas at the surface. Volatiles – Materials that turn into gas at the surface. HH22O, COO, CO22,, CHCH44,, and SOand SO22

Volatiles are released from volcanic eruption. Volatiles are released from volcanic eruption.


A Layered EarthA Layered EarthA Layered EarthA Layered Earth We live on the thin outer skin of Earth. We live on the thin outer skin of Earth. Early perceptions about Earth’s interior were wrong.Early perceptions about Earth’s interior were wrong.

Open caverns filled with magma, water, and air.Open caverns filled with magma, water, and air. Furnaces and flames.Furnaces and flames.

We now know that Earth is comprised of layers.We now know that Earth is comprised of layers. The Crust.The Crust. The Mantle.The Mantle. The Core.The Core.

Outer Core.Outer Core.Inner Core.Inner Core.

We live on the thin outer skin of Earth. We live on the thin outer skin of Earth. Early perceptions about Earth’s interior were wrong.Early perceptions about Earth’s interior were wrong.

Open caverns filled with magma, water, and air.Open caverns filled with magma, water, and air. Furnaces and flames.Furnaces and flames.

We now know that Earth is comprised of layers.We now know that Earth is comprised of layers. The Crust.The Crust. The Mantle.The Mantle. The Core.The Core.

Outer Core.Outer Core.Inner Core.Inner Core.


A Layered EarthA Layered EarthA Layered EarthA Layered Earth Several clues indicate a layered structure.Several clues indicate a layered structure. Density – Plumb bob deflection estimates density.Density – Plumb bob deflection estimates density.

Average density greater than surface density.Average density greater than surface density. Density must increase with depth. Density must increase with depth.

Shape – A rotating sphere requires centered mass. Shape – A rotating sphere requires centered mass. Mass away from center would result in a flattened disk.Mass away from center would result in a flattened disk. Solid interior - Surface doesn’t undulate from tidal forces.Solid interior - Surface doesn’t undulate from tidal forces.

Several clues indicate a layered structure.Several clues indicate a layered structure. Density – Plumb bob deflection estimates density.Density – Plumb bob deflection estimates density.

Average density greater than surface density.Average density greater than surface density. Density must increase with depth. Density must increase with depth.

Shape – A rotating sphere requires centered mass. Shape – A rotating sphere requires centered mass. Mass away from center would result in a flattened disk.Mass away from center would result in a flattened disk. Solid interior - Surface doesn’t undulate from tidal forces.Solid interior - Surface doesn’t undulate from tidal forces.


A Layered EarthA Layered EarthA Layered EarthA Layered Earth Earthquake clues - Earthquake energy transmitted Earthquake clues - Earthquake energy transmitted

as seismic waves that pass through Earth.as seismic waves that pass through Earth. Seismic waves have been used to probe the interior. Seismic waves have been used to probe the interior.

Wave velocity changes with density.Wave velocity changes with density.Velocity changes give depth of layer changes. Velocity changes give depth of layer changes.

Changes with depth.Changes with depth. Pressure. Pressure. Temperature. Temperature.

Earthquake clues - Earthquake energy transmitted Earthquake clues - Earthquake energy transmitted as seismic waves that pass through Earth.as seismic waves that pass through Earth. Seismic waves have been used to probe the interior. Seismic waves have been used to probe the interior.

Wave velocity changes with density.Wave velocity changes with density.Velocity changes give depth of layer changes. Velocity changes give depth of layer changes.

Changes with depth.Changes with depth. Pressure. Pressure. Temperature. Temperature.


Earth (and other planets) have layered interiors.Earth (and other planets) have layered interiors. CrustCrust

Continental Continental OceanicOceanic

MantleMantleUpperUpperLowerLower

CoreCoreOuter – LiquidOuter – LiquidInner – SolidInner – Solid

Earth (and other planets) have layered interiors.Earth (and other planets) have layered interiors. CrustCrust

Continental Continental OceanicOceanic

MantleMantleUpperUpperLowerLower

CoreCoreOuter – LiquidOuter – LiquidInner – SolidInner – Solid

Earth’s Interior LayersEarth’s Interior LayersEarth’s Interior LayersEarth’s Interior Layers

© W. W. Norton© W. W. Norton


The CrustThe CrustThe CrustThe Crust The outermost “skin” of Earth with variable thickness.The outermost “skin” of Earth with variable thickness.

Thickest under mountain ranges (70 km – 40 miles).Thickest under mountain ranges (70 km – 40 miles). Thinnest under mid-ocean ridges (3 km – 2 miles).Thinnest under mid-ocean ridges (3 km – 2 miles).

The Mohorovicic discontinuity is the lower boundary.The Mohorovicic discontinuity is the lower boundary. Separates the crust from the upper mantle. Separates the crust from the upper mantle. Discovered in 1909 by Andrija Mohorovicic.Discovered in 1909 by Andrija Mohorovicic. Marked by a change in the velocity of seismic P waves. Marked by a change in the velocity of seismic P waves.

The outermost “skin” of Earth with variable thickness.The outermost “skin” of Earth with variable thickness. Thickest under mountain ranges (70 km – 40 miles).Thickest under mountain ranges (70 km – 40 miles). Thinnest under mid-ocean ridges (3 km – 2 miles).Thinnest under mid-ocean ridges (3 km – 2 miles).

The Mohorovicic discontinuity is the lower boundary.The Mohorovicic discontinuity is the lower boundary. Separates the crust from the upper mantle. Separates the crust from the upper mantle. Discovered in 1909 by Andrija Mohorovicic.Discovered in 1909 by Andrija Mohorovicic. Marked by a change in the velocity of seismic P waves. Marked by a change in the velocity of seismic P waves.


Two Types of CrustTwo Types of Crust Two Types of CrustTwo Types of Crust Continental crust – Underlies the continents.Continental crust – Underlies the continents.

Average rock density about 2.7 g/cmAverage rock density about 2.7 g/cm33.. Average thickness 35-40 km.Average thickness 35-40 km. Granitic in composition. Granitic in composition.

Oceanic crust – Underlies the ocean basins.Oceanic crust – Underlies the ocean basins. Density about 3.0 g/cmDensity about 3.0 g/cm33. . Avg. thickness 7-10 km.Avg. thickness 7-10 km. Basaltic in composition. Basaltic in composition.

Continental crust – Underlies the continents.Continental crust – Underlies the continents. Average rock density about 2.7 g/cmAverage rock density about 2.7 g/cm33.. Average thickness 35-40 km.Average thickness 35-40 km. Granitic in composition. Granitic in composition.

Oceanic crust – Underlies the ocean basins.Oceanic crust – Underlies the ocean basins. Density about 3.0 g/cmDensity about 3.0 g/cm33. . Avg. thickness 7-10 km.Avg. thickness 7-10 km. Basaltic in composition. Basaltic in composition.


Two Types of CrustTwo Types of Crust Two Types of CrustTwo Types of Crust Crustal density controls surface position. Crustal density controls surface position.

Continental crust Continental crust Less dense; “floats higher.”Less dense; “floats higher.”

Oceanic crust Oceanic crust More dense: “floats lower.”More dense: “floats lower.”

Crustal density controls surface position. Crustal density controls surface position. Continental crust Continental crust

Less dense; “floats higher.”Less dense; “floats higher.” Oceanic crust Oceanic crust

More dense: “floats lower.”More dense: “floats lower.”


Crustal CompositionCrustal CompositionCrustal CompositionCrustal Composition 98.5% of the crust is comprised of just 8 elements.98.5% of the crust is comprised of just 8 elements. Oxygen is (by far!) the most abundant element in the crust.Oxygen is (by far!) the most abundant element in the crust.

This reflects the importance of silicate (SiOThis reflects the importance of silicate (SiO44-based) minerals.-based) minerals.

As a large atom, oxygen occupies ~93% of crustal volume.As a large atom, oxygen occupies ~93% of crustal volume.

98.5% of the crust is comprised of just 8 elements.98.5% of the crust is comprised of just 8 elements. Oxygen is (by far!) the most abundant element in the crust.Oxygen is (by far!) the most abundant element in the crust.

This reflects the importance of silicate (SiOThis reflects the importance of silicate (SiO44-based) minerals.-based) minerals.

As a large atom, oxygen occupies ~93% of crustal volume.As a large atom, oxygen occupies ~93% of crustal volume.


Earth’s MantleEarth’s Mantle Earth’s MantleEarth’s Mantle Solid rock layer between the crust and the core. Solid rock layer between the crust and the core. 2,885 km thick, the mantle is 82% of Earth’s volume. 2,885 km thick, the mantle is 82% of Earth’s volume. Mantle composition is the ultramafic rock peridotite.Mantle composition is the ultramafic rock peridotite. Below ~100-150 km, the rock is hot enough to flow. Below ~100-150 km, the rock is hot enough to flow. It convects: hot mantle rises, cold mantle sinks. It convects: hot mantle rises, cold mantle sinks. Three subdivisions: upper, transitional, and lower. Three subdivisions: upper, transitional, and lower.

Solid rock layer between the crust and the core. Solid rock layer between the crust and the core. 2,885 km thick, the mantle is 82% of Earth’s volume. 2,885 km thick, the mantle is 82% of Earth’s volume. Mantle composition is the ultramafic rock peridotite.Mantle composition is the ultramafic rock peridotite. Below ~100-150 km, the rock is hot enough to flow. Below ~100-150 km, the rock is hot enough to flow. It convects: hot mantle rises, cold mantle sinks. It convects: hot mantle rises, cold mantle sinks. Three subdivisions: upper, transitional, and lower. Three subdivisions: upper, transitional, and lower.


The CoreThe CoreThe CoreThe Core An iron-rich sphere with a radius of 3,471 km. An iron-rich sphere with a radius of 3,471 km. 2 components with differing seismic wave behavior.2 components with differing seismic wave behavior.

Flow in the outer core generates the magnetic field.Flow in the outer core generates the magnetic field.

An iron-rich sphere with a radius of 3,471 km. An iron-rich sphere with a radius of 3,471 km. 2 components with differing seismic wave behavior.2 components with differing seismic wave behavior.

Flow in the outer core generates the magnetic field.Flow in the outer core generates the magnetic field.

Outer coreOuter coreLiquid iron-nickel-sulfurLiquid iron-nickel-sulfur2,255 km thick2,255 km thickDensity – 10-12 g/cmDensity – 10-12 g/cm33

Inner core Inner core Solid iron-nickel alloySolid iron-nickel alloyRadius of 1,220 km.Radius of 1,220 km.Density – 13 g/cmDensity – 13 g/cm33

Outer coreOuter coreLiquid iron-nickel-sulfurLiquid iron-nickel-sulfur2,255 km thick2,255 km thickDensity – 10-12 g/cmDensity – 10-12 g/cm33

Inner core Inner core Solid iron-nickel alloySolid iron-nickel alloyRadius of 1,220 km.Radius of 1,220 km.Density – 13 g/cmDensity – 13 g/cm33


Lithosphere-AsthenosphereLithosphere-AsthenosphereLithosphere-AsthenosphereLithosphere-Asthenosphere Lithosphere – The outermost 100-150 km of Earth.Lithosphere – The outermost 100-150 km of Earth.

Behaves as a non-flowing, rigid material. Behaves as a non-flowing, rigid material. The material that moves as tectonic plates.The material that moves as tectonic plates. Made of 2 components: crust and upper mantle. Made of 2 components: crust and upper mantle.

Asthenosphere – Upper mantle Asthenosphere – Upper mantle belowbelow lithosphere. lithosphere. Shallower under oceanic lithosphere.Shallower under oceanic lithosphere. Deeper under continental lithosphere. Deeper under continental lithosphere. Flows as a soft solid.Flows as a soft solid.

Lithosphere – The outermost 100-150 km of Earth.Lithosphere – The outermost 100-150 km of Earth. Behaves as a non-flowing, rigid material. Behaves as a non-flowing, rigid material. The material that moves as tectonic plates.The material that moves as tectonic plates. Made of 2 components: crust and upper mantle. Made of 2 components: crust and upper mantle.

Asthenosphere – Upper mantle Asthenosphere – Upper mantle belowbelow lithosphere. lithosphere. Shallower under oceanic lithosphere.Shallower under oceanic lithosphere. Deeper under continental lithosphere. Deeper under continental lithosphere. Flows as a soft solid.Flows as a soft solid.


Earth’s Interior Earth’s Interior



Chapter 2Journey to the Center of the Earth

©2008 W. W. Norton & Company, Inc.

Portrait of a PlanetThird Edition

earthearth

LECTURE OUTLINE

This concludes the

op ch02 lecture_earth3

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solar wind

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stronger magnetic field

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solar system visitors