Earth: Portrait of a Planet

Earth: Portrait of a Planet, 4th edition, by Stephen Marshak Earth: Portrait of a Planet, 4th edition, by Stephen Marshak Chapter 2: Journey to the Center of the Earth Chapter 2: Journey to the Center of the Earth© 2011, W. W. Norton

Chapter 2Journey to the Center of the EarthJourney to the Center of the Earth


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

Prepared by:Prepared by:

Ronald ParkerRonald Parker, , Senior GeologistSenior Geologist

Fronterra Geosciences,Fronterra Geosciences,

Denver, ColoradoDenver, Colorado


Earth’s SurfaceEarth’s Surface Our experience with Earth is limited to its surface.Our experience with Earth is limited to its surface. Dramatic elevation changes—mountains, canyons—are Dramatic elevation changes—mountains, canyons—are

tiny “scratches” on this surface.tiny “scratches” on this surface. Our Earth is much more vast and complex than the Our Earth is much more vast and complex than the

surface suggests.surface suggests.

Fig. 2.0


A Journey through SpaceA Journey through Space A probe to Earth from an extra-solar planet, would:A probe to Earth from an extra-solar planet, would:

Traverse the profound vacuum of interstellar space.Traverse the profound vacuum of interstellar space. Encounter the diffuse edge of the Solar System, which is:Encounter the diffuse edge of the Solar System, which is:

Defined by the faint pull of the Sun’s gravity.Defined by the faint pull of the Sun’s gravity.Populated by fragments of ice and rock, the Oort Cloud.Populated by fragments of ice and rock, the Oort Cloud.50,000 AUs from the Sun. (One AU, an astronomical unit, is 50,000 AUs from the Sun. (One AU, an astronomical unit, is

the distance between Earth and the Sun, 93 million miles).the distance between Earth and the Sun, 93 million miles).


The Solar SystemThe Solar System The boundary of the heliosphere is 200 AU from the Sun.The boundary of the heliosphere is 200 AU from the Sun.

This is the outer reach of the solar wind.This is the outer reach of the solar wind. The Kuiper Belt is an diffuse band of icy objects.The Kuiper Belt is an diffuse band of icy objects.

Some are up to 1,200 km across.Some are up to 1,200 km across. Comets originate here.Comets originate here. Neptune is the inner edge.Neptune is the inner edge.

Neptune’s orbit defines Neptune’s orbit defines

interplanetary space.interplanetary space.

Fig. 2.1


The PlanetsThe Planets All planetary orbits lie on the same plane (the ecliptic).All planetary orbits lie on the same plane (the ecliptic). Eight planets constitute the Solar System.Eight planets constitute the Solar System.

Outer ice-giant planets (Neptune and Uranus)Outer ice-giant planets (Neptune and Uranus) Gas-giant planets (Saturn and Jupiter)Gas-giant planets (Saturn and Jupiter) Terrestrial planets (Mars, Earth, Venus, and Mercury)Terrestrial planets (Mars, Earth, Venus, and Mercury)

The asteroid belt lies between Jupiter and Mars.The asteroid belt lies between Jupiter and Mars.

Fig. 2.5


AsteroidsAsteroids Asteroids: small bodies of rock or metal orbiting the Asteroids: small bodies of rock or metal orbiting the

Sun.Sun. Planetesimals that were never part of a larger planet.Planetesimals that were never part of a larger planet. Fragmented larger planetesimals.Fragmented larger planetesimals. Most occur in a belt between Jupiter and Mars.Most occur in a belt between Jupiter and Mars. Range in size.Range in size.

Up to 30 km acrossUp to 30 km acrossMillions >1km in diameterMillions >1km in diameterToo small to be reshaped Too small to be reshaped

by gravityby gravity Asteroids can strike Earth.Asteroids can strike Earth.

Fig. Bx2.1a


CometsComets Comets: icy planetesimals that orbit the Sun.Comets: icy planetesimals that orbit the Sun.

They traverse highly elliptical orbits around the Sun.They traverse highly elliptical orbits around the Sun. When approaching the Sun, they develop a long coma (tail).When approaching the Sun, they develop a long coma (tail).

The tail is comprised of evaporating gas and dust.The tail is comprised of evaporating gas and dust.The tail always points away from the Sun.The tail always points away from the Sun.

Short-period comets originate in the Kuiper Belt.Short-period comets originate in the Kuiper Belt. Longer period comets may derive from the Oort Cloud.Longer period comets may derive from the Oort Cloud. ““Dirty snowballs” made of:Dirty snowballs” made of:

HH22O, COO, CO22, CH, CH44, NH, NH33

Other volatilesOther volatilesOrganic compounds Organic compounds DustDust

Comets can strike Earth.Comets can strike Earth.

Fig. Bx2.1b


Magnetic FieldMagnetic Field Space visitors would notice Earth’s magnetic field.Space visitors would notice Earth’s magnetic field. Earth’s magnetic field is like a giant dipole bar magnet.Earth’s magnetic field is like a giant dipole bar magnet.

The field has north and south ends. The field has north and south ends. The field grows weaker with distance.The field grows weaker with distance. The magnetic flux is directional.The magnetic flux is directional.

Flows from S pole to N pole along the bar magnetFlows from S pole to N pole along the bar magnetFlows from N to S along field lines outside the barFlows from N to S along field lines outside the bar

Fig. 2.3a


Magnetic FieldMagnetic Field Earth’s magnetic field is like a giant dipole bar magnet.Earth’s magnetic field is like a giant dipole bar magnet. The N pole of the bar is near Earth’s geographic S pole.The N pole of the bar is near Earth’s geographic S pole.

A compass needle aligns with the field lines.A compass needle aligns with the field lines. The N compass arrow points to the bar magnet S pole.The N compass arrow points to the bar magnet S pole.

Opposites attract.Opposites attract. Magnetic field lines:Magnetic field lines:

Extend into space.Extend into space. Weaken with distance.Weaken with distance. Form a shield aroundForm a shield around

Earth (magnetosphere).Earth (magnetosphere).

Fig. 2.3b


Magnetic FieldMagnetic Field The solar wind distorts the magnetosphere.The solar wind distorts the magnetosphere.

Shaped like a teardropShaped like a teardrop Deflects most of the solar wind, protecting EarthDeflects most of the solar wind, protecting Earth

The strong magnetic field of the Van Allen belts arrests The strong magnetic field of the Van Allen belts arrests deadly cosmic radiation. deadly cosmic radiation.

Fig. 2.3c


Magnetic FieldMagnetic Field The magnetic field is revealed by spectacular aurorae. The magnetic field is revealed by spectacular aurorae.

Some charged particles make it past the Van Allen belts.Some charged particles make it past the Van Allen belts. These are channeled along magnetic field lines.These are channeled along magnetic field lines. They cause atmospheric gases in polar regions to glow.They cause atmospheric gases in polar regions to glow.

Northern lights: aurora borealis.Northern lights: aurora borealis. Southern lights: aurora australis.Southern lights: aurora australis.

Fig. 2.3d


Our atmosphere is mostly nitrogen (NOur atmosphere is mostly nitrogen (N22) and oxygen (O) and oxygen (O22).). The remaining gases, (totaling less than 1%) include:The remaining gases, (totaling less than 1%) include:

Argon (0.93%), carbon dioxide (0.039%), neon (0.0018%)Argon (0.93%), carbon dioxide (0.039%), neon (0.0018%) Other, less common, gases (helium, methane, krypton).Other, less common, gases (helium, methane, krypton).

The atmosphere thins away from Earth.The atmosphere thins away from Earth. Atmospheric layers have distinct characteristics.Atmospheric layers have distinct characteristics.

Pressure, temperature, density, moisture compositionPressure, temperature, density, moisture composition

The AtmosphereThe Atmosphere

Fig. 2.4a,b


The atmosphere is more dense closer to Earth.The atmosphere is more dense closer to Earth. Sea-level atmospheric pressure:Sea-level atmospheric pressure:

14.7 pounds per square inch (psi)14.7 pounds per square inch (psi) 1.01 bar1.01 bar

With increasing elevation:With increasing elevation: Pressure decreases.Pressure decreases. Density decreases.Density decreases. Oxygen content decreases. Oxygen content decreases.


Fig. 2.4c


Atmospheric layers are separated by pauses.Atmospheric layers are separated by pauses. Troposphere (0–11 km): Troposphere (0–11 km):

The lower mixing layer.The lower mixing layer.Weather is confined to this layer.Weather is confined to this layer.Temperature decreases upward.Temperature decreases upward.

Stratosphere (12–47 km):Stratosphere (12–47 km):No mixing occurs.No mixing occurs.Temperature increases upward.Temperature increases upward.

Mesosphere (47–82 km):Mesosphere (47–82 km):Temperature decreases upward.Temperature decreases upward.

Thermosphere (82 km+):Thermosphere (82 km+):Outermost layer.Outermost layer.Temperature increases upward.Temperature increases upward.


Fig. 2.4d


The Earth System The Earth System Orbiting around Earth, space visitors would notice:Orbiting around Earth, space visitors would notice:

Atmosphere—the gaseous envelope.Atmosphere—the gaseous envelope. Hydrosphere—the blue liquid water. Hydrosphere—the blue liquid water. Cryosphere—the frozen world.Cryosphere—the frozen world. Biosphere—the wealth of life.Biosphere—the wealth of life. Lithosphere—the solid Earth.Lithosphere—the solid Earth.

Interaction of these componentsInteraction of these components interactions, interactions, comprises the Earth System.comprises the Earth System.

Earth is in the habitable zone.Earth is in the habitable zone. Only Earth has liquid water, andOnly Earth has liquid water, and

hence, life.hence, life.

Fig. 2.2


Land and water are the most prominent surface features. Land and water are the most prominent surface features.

Icecaps and living organisms are also in evidence.Icecaps and living organisms are also in evidence.

Earth’s SurfaceEarth’s Surface

Fig. 2.6


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 in depth.Most ocean floors are close to 5 km in depth. Extreme highs or lows of depth or height are rare.Extreme highs or lows of depth or height are rare. The two dominant “levels” reflect continental vs. oceanic The two dominant “levels” reflect continental vs. oceanic

crust. crust.

Hypsometric CurveHypsometric Curve

Fig. 2.7


91.2% of Earth is comprised of just four elements. 91.2% of Earth is comprised of just four elements. Iron (Fe)—32.1%Iron (Fe)—32.1% Oxygen (O)—30.1%Oxygen (O)—30.1% Silicon (Si)—15.1%Silicon (Si)—15.1% Magnesium (Mg)—13.9% Magnesium (Mg)—13.9%

The remaining eighty-eight are naturally occurring The remaining eighty-eight are naturally occurring elements: 8.8%elements: 8.8%

These ratios differ for Earth’s crust. These ratios differ for Earth’s crust.

Elemental CompositionElemental Composition

Fig. 2.8


Earth 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.These include wood, peat, lignite, coal, and oil. These include wood, peat, lignite, coal, and oil. Geologically rare (organic in contact with oxygen).Geologically rare (organic in contact with oxygen).



Minerals—naturally-occurring crystalline solids.Minerals—naturally-occurring crystalline solids.Crystal—a single coherent mineral with geometric faces.Crystal—a single coherent mineral with geometric faces.Grain—an irregularly shaped fragment of a larger crystal.Grain—an irregularly shaped fragment of a larger crystal.Minerals comprise rocks and, therefore, most of the earth.Minerals comprise rocks and, therefore, most of the earth.

Glasses—noncrystalline solids. Glasses—noncrystalline solids. Glasses form by rapid cooling—too fast for crystal growth.Glasses form by rapid cooling—too fast for crystal growth.



Rocks—aggregates of minerals, grains, and/or glass.Rocks—aggregates of minerals, grains, and/or glass. Igneous—cooled from a liquid (melt).Igneous—cooled from a liquid (melt).Sedimentary—debris cemented from preexisting rock. Sedimentary—debris cemented from preexisting rock. Metamorphic—rock altered by pressure and temperature.Metamorphic—rock altered by pressure and temperature.

Rocks may be made of a single mineral.Rocks may be made of a single mineral.



Sediment—an accumulation of loose mineral grains.Sediment—an accumulation of loose mineral grains.Weathered and eroded from preexisting rocks.Weathered and eroded from preexisting rocks.Precipitated from evaporating water.Precipitated from evaporating water.

Metals—solids composed of metal atoms (Al, Fe, Cu, Sn).Metals—solids composed of metal atoms (Al, Fe, Cu, Sn).Metals have high density, are shiny and conduct electricity.Metals have high density, are shiny and conduct electricity.



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, CO2, 2, CHCH4 4 and SOand SO22

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


Earth MaterialsEarth Materials Most rocks on Earth are silicates (based on Si and O).Most rocks on Earth are silicates (based on Si and O). There are four fundamental silicate igneous rock types.There are four fundamental silicate igneous rock types.

Vary by silica (SiOVary by silica (SiO44) to iron (Fe) and magnesium (Mg).) to iron (Fe) and magnesium (Mg).Felsic—most Si-rich, Fe and Mg-poor. Ex: GraniteFelsic—most Si-rich, Fe and Mg-poor. Ex: Granite IntermediateIntermediateMaficMaficUltramafic—most Ultramafic—most

Si-poor, Fe and Si-poor, Fe and

Mg-rich. Mg-rich.

Ex: PeridotiteEx: Peridotite


A Layered EarthA Layered Earth How do we know that the Earth has a layered interior?How do we know that the Earth has a layered interior? Early speculations sought to explain:Early speculations sought to explain:

The source of lava.The source of lava. Gem and mineral enrichment.Gem and mineral enrichment. Spring waters.Spring waters. Earthquakes.Earthquakes.

Early guesses were wrong.Early guesses were wrong. Open caverns to the interiorOpen caverns to the interior Flowing lava, air, waterFlowing lava, air, water

Fig. 2.9


A Layered EarthA Layered Earth The first key to understanding Earth’s interior: density.The first key to understanding Earth’s interior: density.

A plumb bob is deflected by a nearby mountain mass.A plumb bob is deflected by a nearby mountain mass. Degree of deflection can be used to calculate Earth’s mass. Degree of deflection can be used to calculate Earth’s mass. The density from this method (4.5 g/cmThe density from this method (4.5 g/cm33) is much higher ) is much higher

than the density of the thin outer crust (2.5 g/cmthan the density of the thin outer crust (2.5 g/cm33). ). This suggests that density must increase with depth. This suggests that density must increase with depth.

Fig. 2.10


A Layered EarthA Layered Earth The first key to understanding Earth’s interior: density.The first key to understanding Earth’s interior: density.

In 1896, Emil Wiechert made important contributions.In 1896, Emil Wiechert made important contributions.He determined that metal must be present in Earth’s interior.He determined that metal must be present in Earth’s interior.He deduced that the metal must occur at the Earth’s center.He deduced that the metal must occur at the Earth’s center.

We now know he was correct. We now know he was correct. His ideas led to a model:His ideas led to a model:

Earth is like an egg.Earth is like an egg. Thin, light crust (eggshell)Thin, light crust (eggshell) Thicker, more dense mantle (eggwhite)Thicker, more dense mantle (eggwhite) Innermost, very dense core (yolk)Innermost, very dense core (yolk)

Other density observations:Other density observations:The land doesn’t have large tides, hence Earth must be solid.The land doesn’t have large tides, hence Earth must be solid.

Fig. 2.11


A Layered EarthA Layered Earth Earthquakes: seismic energy from fault motion.Earthquakes: seismic energy from fault motion.

Seismic waves provide insight into Earth’s interior. Seismic waves provide insight into Earth’s interior. Seismic wave velocities change with density.Seismic wave velocities change with density.We can determine the depth of seismic velocity changes.We can determine the depth of seismic velocity changes.Hence, we can tell where densities change in Earth’s interior. Hence, we can tell where densities change in Earth’s interior.

Fig. 2.12


A Layered EarthA Layered Earth Changes with depth.Changes with depth.

Pressure (P)Pressure (P)The weight of overlyingThe weight of overlying

rock increases with depth.rock increases with depth. Temperature (T)Temperature (T)

Heat is generated inHeat is generated in

Earth’s interior.Earth’s interior. T increases with depth. T increases with depth.

Geothermal gradientGeothermal gradient The rate of T changes with depth.The rate of T changes with depth. The geothermal gradient varies.The geothermal gradient varies.

High of 50°C per kmHigh of 50°C per kmLow of 15°C per kmLow of 15°C per kmDetermined by tectonic settingDetermined by tectonic setting Fig. 2.13


Layer CompositionsLayer Compositions Geologists strived to understand the nature of the layers.Geologists strived to understand the nature of the layers.

Studied meteorites as analogues for core and mantle.Studied meteorites as analogues for core and mantle. Conducted laboratory experiments.Conducted laboratory experiments.

Density measurements of rocks from the interiorDensity measurements of rocks from the interiorCharacteristics of mantle-derived rocks and mineralsCharacteristics of mantle-derived rocks and mineralsDetermined high P and T stability field of rocks and mineralsDetermined high P and T stability field of rocks and minerals

Fig. Bx.2.2c


Layer CompositionsLayer Compositions End result of a century of investigation? End result of a century of investigation?

We know much about the nature of Earth’s interior.We know much about the nature of Earth’s interior. This knowledge continues to evolve.This knowledge continues to evolve.

Earth’s layers consist of the crust, upper, transitional, and Earth’s layers consist of the crust, upper, transitional, and lower mantles, and liquid outer and solid inner cores.lower mantles, and liquid outer and solid inner cores.

Much complexity characterizes even these layers.Much complexity characterizes even these layers.

Geology at a Glance


The CrustThe Crust The outermost “skin” of our planet; highly variable.The outermost “skin” of our planet; highly variable.

Thickest under mountain ranges (70 km or 40 miles).Thickest under mountain ranges (70 km or 40 miles). Thinnest under mid-ocean ridges (7 km or 4 miles).Thinnest under mid-ocean ridges (7 km or 4 miles).

Relatively as thick as the membrane of a toy balloon.Relatively as thick as the membrane of a toy balloon. The Mohorovičić discontinuity (Moho) is the base.The Mohorovičić discontinuity (Moho) is the base.

Seismic velocity change between crust and upper mantle.Seismic velocity change between crust and upper mantle. The crust is the upper part of a tectonic plate.The crust is the upper part of a tectonic plate.

Fig. 2.14a


The CrustThe Crust There are two kinds of crust: There are two kinds of crust: continentalcontinental and and oceanicoceanic..

Continental crust underlies the continents.Continental crust underlies the continents.Average density of ~2.7 g/cmAverage density of ~2.7 g/cm33

Average thickness 35–40 kmAverage thickness 35–40 kmFelsic (granitic) to intermediate in composition. Felsic (granitic) to intermediate in composition.

Oceanic crust underlies the ocean basins.Oceanic crust underlies the ocean basins.Average density of ~3.0 g/cmAverage density of ~3.0 g/cm33

Average thickness 7–10 kmAverage thickness 7–10 kmMafic (basaltic and gabbroic) in composition. Mafic (basaltic and gabbroic) in composition.

Fig. 2.14a


The CrustThe Crust There are two kinds of crust: There are two kinds of crust: continentalcontinental and and oceanicoceanic.. 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”

Fig. 2.14c


98.5% of the crust is comprised of just eight elements.98.5% of the crust is comprised of just eight elements. Oxygen is the most abundant element in the crust.Oxygen is the most abundant element in the crust.

This reflects the importance of silicate (SiOThis reflects the importance of silicate (SiO44) minerals.) minerals. Oxygen is large. It occupies ~93% of crustal volume.Oxygen is large. It occupies ~93% of crustal volume.

Crustal CompositionCrustal Composition

Fig. 2.15


Solid rock, 2,885 km thick, 82% of Earth’s volume. Solid rock, 2,885 km thick, 82% of Earth’s volume. The mantle is entirely the ultramafic rock peridotite.The mantle is entirely the ultramafic rock peridotite. Convection below 100 km mixes the mantle.Convection below 100 km mixes the mantle.

Like oatmeal on a stove: hot rises, cold sinks.Like oatmeal on a stove: hot rises, cold sinks. Convection aids tectonic plate motion.Convection aids tectonic plate motion.

Upper, transitional, and lower. Upper, transitional, and lower.

The MantleThe Mantle

Fig. Bx2.3c

Geology at a Glance


An iron-rich sphere with a radius of 3,471 km. An iron-rich sphere with a radius of 3,471 km. Seismic waves segregate two radically different parts.Seismic waves segregate two radically different parts.

The outer core is liquid; inner core solid.The outer core is liquid; inner core solid. Outer coreOuter core

Liquid iron-nickel-sulfurLiquid iron-nickel-sulfur 2,255 km thick2,255 km thick Density is 10–12 g/cmDensity is 10–12 g/cm33

Inner core Inner core Solid iron-nickel alloySolid iron-nickel alloy Radius of 1,220 kmRadius of 1,220 km Density is 13 g/cmDensity is 13 g/cm33

Outer core flow generates Outer core flow generates

Earth’s magnetic field.Earth’s magnetic field.

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

The CoreThe Core

Geology at a Glance


Earth has a layered interior.Earth has a layered interior. CrustCrust

Continental Continental OceanicOceanic

MantleMantleUpperUpperTransitional Transitional LowerLower

CoreCoreOuter—liquidOuter—liquid Inner—solidInner—solid

These layers are subdivided These layers are subdivided

on the basis of seismic waves.on the basis of seismic waves.

Summarizing Earth’s LayersSummarizing Earth’s Layers

Fig. 2.14b


Lithosphere-AsthenosphereLithosphere-Asthenosphere We can also regard layering based on rock strength.We can also regard layering based on rock strength.

Lithosphere—the outermost 100–150 km of Earth.Lithosphere—the outermost 100–150 km of Earth.Behaves rigidly, as a nonflowing material. Behaves rigidly, as a nonflowing material. Comprised of two components: crust and upper mantle. Comprised of two components: crust and upper mantle. This is the material that makes up tectonic plates.This is the material that makes up tectonic plates.

Asthenosphere—upper mantle Asthenosphere—upper mantle belowbelow the lithosphere. the lithosphere. Shallow under oceanic lithosphere; deeper under continental. Shallow under oceanic lithosphere; deeper under continental. Flows as a soft solid.Flows as a soft solid.

Fig. 2.16


NASA Solar System ExplorationNASA Solar System Exploration http://solarsystem.nasa.gov/index.cfmhttp://solarsystem.nasa.gov/index.cfm

AGU Geomagnetism and PaleomagnetismAGU Geomagnetism and Paleomagnetism http://www.agu.org/sections/geomag/background.htmlhttp://www.agu.org/sections/geomag/background.html

NOAA Weather and Atmosphere NOAA Weather and Atmosphere http://www.education.noaa.gov/Weather_and_Atmosphere/http://www.education.noaa.gov/Weather_and_Atmosphere/

USGS Earthquake Hazards ProgramUSGS Earthquake Hazards Program http://earthquake.usgs.gov/earthquakes/http://earthquake.usgs.gov/earthquakes/

NESTA Structure of the Interior of the EarthNESTA Structure of the Interior of the Earth http://www.windows2universe.org/earth/Interior_Structure/interior.htmlhttp://www.windows2universe.org/earth/Interior_Structure/interior.html

Useful Web ResourcesUseful Web Resources


Photo CreditsPhoto Credits


W. W. Norton & CompanyW. W. Norton & CompanyIndependent and Employee-OwnedIndependent and Employee-Owned

This concludes the Norton Media LibraryThis concludes the Norton Media LibraryPowerPoint Slide Set for Chapter 2PowerPoint Slide Set for Chapter 2

Earth: Portrait of a PlanetEarth: Portrait of a Planet

44thth edition (2011) edition (2011)

by Stephen Marshakby Stephen Marshak

Powerpoint slides prepared by Powerpoint slides prepared by

Ronald L. ParkerRonald L. ParkerSenior Geologist, Senior Geologist,

Fronterra Geosciences, Fronterra Geosciences,

Denver, ColoradoDenver, Colorado

Earth: Portrait of a Planet

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Transcript of Earth: Portrait of a Planet