NEW - Earth's Geologic History-Interior - Quia · PDF fileExtensive coal-forming forests ......

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Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc.

ALL RIGHTS RESERVED.

The EarthThe Earth’’s Geologic Historys Geologic History

andand

The EarthThe Earth’’s Interiors Interior



EarthEarth’’s Geologic Historys Geologic History�� Geologic timescaleGeologic timescale

•• Divides EarthDivides Earth’’s history into relative s history into relative timetimeperiodsperiods

•• Relative dating based onRelative dating based on::(apply for entire universe)(apply for entire universe)

�� Principle of Principle of superposition superposition ((rock layersrock layers))

�� Principle of Principle of crosscross--cutting relationshipscutting relationships

((A rock or fault is younger than any rock (or A rock or fault is younger than any rock (or faultfault))

through which it cuts.through which it cuts.))

••Igneous intrusions, faultsIgneous intrusions, faults

www.classzone.comwww.classzone.com



FossilsFossils

�� Provide Provide informationinformation on geologic timescaleon geologic timescale

�� Three basic ways fossils can be preservedThree basic ways fossils can be preserved::

•• Original preservationOriginal preservation——preserved actual preserved actual organismorganism

•• MineralizationMineralization——rocklike copy of the originalrocklike copy of the original

•• Fossil impressionFossil impression——impressionimpression in soft in soft sedimentssediments

�� Index fossilsIndex fossils——lived short time on Earthlived short time on Earth

www.kgs.ku.eduCopyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc.


Radiometric DatingRadiometric Dating

�� 18951895 -- Antoine Henri Antoine Henri BecquerelBecquerel

•• Discovered that Discovered that uraniumuranium atoms atoms

undergo undergo radioactive decayradioactive decay

•• Form a Form a new element new element ------ leadlead

•• Occurs at a specific rateOccurs at a specific rate——called called halfhalf--lifelife

�� UseUse::•• Uranium 238Uranium 238——halfhalf--life 4.5 billion yearslife 4.5 billion years

•• Potassium 40Potassium 40——halfhalf--life 1.3 billion yearslife 1.3 billion years

•• Uranium 235Uranium 235——halfhalf--life 700 million yearslife 700 million years

•• Carbon 14Carbon 14——halfhalf--lifelife 5,730 years5,730 years

�� Used because all things living contained carbonUsed because all things living contained carbon





The Geologic Timescale

�� Used to represent Used to represent history of Earthhistory of Earth

�� Largest period is called the Largest period is called the eoneon

�� Three eons make up EarthThree eons make up Earth’’s historys history::

•• ArcheanArchean

•• ProterozoicProterozoic

•• PhanerozoicPhanerozoic

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updatecenter.britannica.compubs.usgs.gov



The Archean EonThe Archean Eon

�� Began approximately Began approximately 4.5 billion years ago4.5 billion years ago

�� Violent timeViolent time in Earthin Earth’’s historys history

�� Bombardment by meteorites and asteroidsBombardment by meteorites and asteroids

•• Evidenced by surface of the MoonEvidenced by surface of the Moon

�� First lifeFirst life--formsforms

•• StromatolitesStromatolites——colonies of singlecolonies of single--celled celled

cyanobacteriacyanobacteria

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Time of origin of Time of origin of

EarthEarth

Geochemical Geochemical

evidence of evidence of

oldest biological oldest biological

fixing carbonfixing carbon

Oldest known Oldest known

rocksrocks

Transition to Transition to

atmosphere atmosphere

containing Ocontaining O22

Oldest Oldest

microfossilsmicrofossils




4.6 billion years 4.6 billion years

agoago

3.4 to 4.6 billion 3.4 to 4.6 billion

years agoyears ago


years agoyears ago


years agoyears ago

StromatolitesStromatolitesEarlyEarly




MiddleMiddle

LateLate

Archean



The Proterozoic EonThe Proterozoic Eon

�� Archean eon Archean eon ended 2.5 billion years agoended 2.5 billion years ago

�� Period before 570 million years agoPeriod before 570 million years ago

•• Included Archean and Proterozoic eonsIncluded Archean and Proterozoic eons

•• Known as Known as PrecambrianPrecambrian timetime

�� Proterozoic ended 570 million years agoProterozoic ended 570 million years ago

•• Entered the eon in which we liveEntered the eon in which we live

•• Called the Called the Phanerozoic Phanerozoic eoneon



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First appearance First appearance

of sexually of sexually

reproducing reproducing

organismsorganisms

Oldest Oldest

multicellular lifemulticellular life


years agoyears ago


years agoyears ago

1.0 billion to 570 1.0 billion to 570

million years agomillion years ago

SoftSoft--bodied bodied

organismsorganismsEarlyEarly

MiddleMiddle

Edicaran faunaEdicaran faunaLateLate

Proterozoic

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The The PhanerozoicPhanerozoic Eon Eon The Paleozoic EraThe Paleozoic Era

�� Phanerozoic eon composed of Phanerozoic eon composed of three time periodsthree time periods::

•• Called Called eraseras

•• Based on the occurrence of Based on the occurrence of mass extinctionsmass extinctions

•• Each era subdivided into specific periodsEach era subdivided into specific periods

�� Paleozoic consists of Paleozoic consists of six periodssix periods





�� Six periods:Six periods:

•• Early began 570 million years agoEarly began 570 million years ago

CambrianCambrian——lasted 65 million yearslasted 65 million years

OrdovicianOrdovician——lasted 67 million yearslasted 67 million years

SilurianSilurian——lasted 30 million yearslasted 30 million years

DevonianDevonian——lasted 45 million yearslasted 45 million years

CarboniferousCarboniferous——lasted 73 million years lasted 73 million years

PermianPermian——lasted 45 million yearslasted 45 million years


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The Phanerozoic EonThe Phanerozoic Eon

505 to 570 505 to 570


438 to 505 438 to 505


408 to 438 408 to 438

million years million years

agoago

Earliest fishEarliest fish

Algal reefsAlgal reefs

Burgess shale faunaBurgess shale fauna

Earliest chordates, diverse Earliest chordates, diverse

trilobitestrilobites

Earliest trilobitesEarliest trilobites

Earliest marine animals with Earliest marine animals with

shellsshells

CambrianCambrian

Invertebrates dominantInvertebrates dominant

——mollusks become abundantmollusks become abundant

Diverse coral and echinodermsDiverse coral and echinoderms

Graptolites abundantGraptolites abundant

OrdovicianOrdovician

Earliest insectsEarliest insects

Earliest land plants and Earliest land plants and

animalsanimals

Peak development of Peak development of

EurypteridsEurypterids

SilurianSilurian

Paleozoic



363 to 408 363 to 408


agoago

290 to 363 290 to 363


agoago

245 to 290 245 to 290


agoago

Earliest amphibians, Earliest amphibians,

ammonoids, sharksammonoids, sharks

Extinction of armored fish, Extinction of armored fish,

other fish abundantother fish abundantDevonianDevonian

Earliest reptilesEarliest reptiles

Extensive coalExtensive coal--forming forestsforming forests

CarboniferoCarboniferousus

Extinction of many kinds of Extinction of many kinds of

marine animals, including marine animals, including

trilobitetrilobite

First mammalFirst mammal--like reptileslike reptiles

PermianPermian

Paleozoic

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The Mesozoic EraThe Mesozoic Era

�� Began approximately 245 million years agoBegan approximately 245 million years ago

�� Three periodsThree periods::

•• TriassicTriassic PeriodPeriod——lasted 37 million yearslasted 37 million years

•• Jurassic Jurassic PeriodPeriod——lasted 62 million yearslasted 62 million years

•• CretaceousCretaceous PeriodPeriod——lasted 81 million yearslasted 81 million years

�� Extinction of dinosaursExtinction of dinosaurs 65 million years ago65 million years ago



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570 to 635 570 to 635


agoago

505 to 438 505 to 438


agoago

438 to 363 438 to 363


agoago

Modern coral groups appearModern coral groups appear

Earliest dinosaurs and Earliest dinosaurs and

mammals with abundant mammals with abundant

cycads and coniferscycads and conifersTriassicTriassic

Earliest birdsEarliest birds

Abundant dinosaurs and Abundant dinosaurs and

ammonoidsammonoidsJurassicJurassic

Extinction of dinosaurs and Extinction of dinosaurs and

ammonoidsammonoids

Earliest placental mammalsEarliest placental mammals

Climax of dinosaurs and Climax of dinosaurs and

ammonoidsammonoids

Earliest flowering plantsEarliest flowering plants

Decline of brachiopodsDecline of brachiopods

Diverse bony fishesDiverse bony fishes

CretaceousCretaceous

Mesozoic



The Cenozoic Era

�� MammalsMammals emerged as dominant lifeemerged as dominant life--formform

�� Began 65 million years agoBegan 65 million years ago

�� Divided into:Divided into:

•• TertiaryTertiary periodperiod——appearance of appearance of grassesgrasses

�� Lasted 63 million yearsLasted 63 million years

�� Divided into periods called Divided into periods called epochsepochs

•• QuaternaryQuaternary——largelarge--scale scale glaciationglaciation

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2 to 65 million 2 to 65 million

years agoyears ago

Present to 2 Present to 2


agoago

Large carnivoresLarge carnivores

Abundant grazing mammalsAbundant grazing mammals

Earliest grassesEarliest grasses

Large running mammalsLarge running mammals

Many modern groups of Many modern groups of

mammalsmammals

Tertiary:Tertiary:

NeogeneNeogene

PaleogenePaleogene

Humans, mastodons, Humans, mastodons,

mammothsmammothsQuaterinaryQuaterinary

Cenozoic



The EarthThe Earth’’s Interiors InteriorA ModelA Model

�� Developed using Developed using seismic wavesseismic waves

�� Deepest drillingDeepest drilling is is 9 miles9 miles

�� Deepest mineDeepest mine is slightly over is slightly over 2 miles2 miles

�� Model is constructed by Model is constructed by inferenceinference---- cancan’’t travel there!t travel there!

Earth is so large Earth is so large

–– cancan’’t be studied by direct observation!t be studied by direct observation!

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Three major layersThree major layers

Core Core ---- MantleMantle ---- CrustCrust



EarthEarth’’s Interiors Interior

1 1 -- The CoreThe Core�� Outer Outer liquidliquid portionportion

�� Inner Inner solidsolid portionportion

�� Composition believed to be Composition believed to be iron and nickeliron and nickel



� 2900 kilometers thick

� 83% of the Earth's volume

� It is solid

�� 1,800 miles to outer core1,800 miles to outer core

�� 1,300 miles to inner core1,300 miles to inner core

�� Core is extremely Core is extremely hot hot

= 8,000= 8,000°°FF

�� Used Used seismic wavesseismic waves to reveal compositionto reveal composition

�� Impossible to observe directlyImpossible to observe directly because it is so because it is so hothot and has extremely and has extremely high pressurehigh pressure



2 2 -- The MantleThe Mantle

�� MostMost of Earthof Earth’’s s volumevolume

�� Composed of a Composed of a hot solidhot solid materialmaterial

•• Silicon, oxygen, iron, aluminum, and Silicon, oxygen, iron, aluminum, and

magnesiummagnesium

•• 1,800 miles thick 1,800 miles thick ---- extremely extremely high high

pressurespressures

•• Heat moves upwardHeat moves upward through mantlethrough mantle

�� Forms Forms convectionconvection cellscells



�� Extreme heat comes fromExtreme heat comes from::

•• Radioactive decayRadioactive decay

•• FrictionFriction

•• Residual heatResidual heat

•• All are left over from EarthAll are left over from Earth’’s formations formation

�� Upper mantle called the Upper mantle called the asthenosphereasthenosphere

•• FlowsFlows like thick syruplike thick syrup

•• Top layer Top layer -- 100 to 200 kilometers100 to 200 kilometers below below

surface. surface.

•• Physical properties are differentPhysical properties are different from the rest from the rest

of the upper mantle of the upper mantle ---- rocks rocks in this upper in this upper

portion of the mantle are portion of the mantle are more rigid and brittlemore rigid and brittle

because of because of cooler temperatures and lower cooler temperatures and lower

pressures. pressures. Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc.


EarthEarth’’s crusts crust floatsfloats on top of upper mantleon top of upper mantle

(Like a cracker floating on soup)(Like a cracker floating on soup)

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3 3 -- CrustCrust

�� Outer portionOuter portion composed of composed of solid rocksolid rock

�� Thickness Thickness from from 40 miles to 3 miles40 miles to 3 miles

•• 40 miles40 miles under under mountainsmountains

•• 3 miles3 miles under parts of the under parts of the oceanocean

�� Oceanic crustOceanic crust made of made of basaltbasalt



SevenSeven elements make up elements make up 99%99% of crustof crust

Oxygen and siliconOxygen and silicon = 72% of the crust= 72% of the crust

Aluminum, iron, calcium, magnesiumAluminum, iron, calcium, magnesium, , sodiumsodium form remainderform remainder



LithosphereLithosphere

Solid outer Solid outer crustcrust of Earthof Earth

Rock and hot plasticRock and hot plastic--like upper like upper mantlemantle





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