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Geology 101

2. Qatar University
College of Arts and Sciences
Chemistry and Earth Sciences Department
Principles of General Geology -GEOL_101
Spring 2024
The Earth and Universe

4. What is the universe?
How did the universe originate?
What is the fastest thing in the universe?
What is the solar system?
The Planet Earth

5. TheUniverse(Latin:universus)isallofspaceandtimeandtheircontents,
includingallformsofmatterandenergy
Energyappearsintheformof:light,heat,motion,orcosmicrays
Matter(solid,liquid,andgas)includes:galaxiesthatconsistof
billionsofstarsinadditiontoplanets,moons,comets,meteors,gas
cloudsanddustcloudscallednebulae
TheUniverseiseverythingwecantouch,feel,sense,measureordetect.It
includeslivingthings,planets,stars,galaxies,dustclouds,light,andeven
time
What is The Universe?
So

6. Origin of the Universe
The Great Cloud
or
The Big Bang Theory
IntheBigBangtheory,theuniversebeganapproximately13.7billionyears
ago
Anextremelydense,hotbodyofmatter(Allmassandenergyinasinglepoint)
expanded
Theuniversecooled
Atomsbegantobond
HydrogenformedH2molecules-Thefuelofstars
Thesimplestelementsformed
Gravitycausedformationofgaseousnebulae
Gravitygraduallydrewmattertogethertoformthefirststarsandthefirst
galaxies

8. Evidences for the Big Bang Theory
Theuniverseisexpandingfromacentralpoint
Hubble’sdiscoveryinthe1920sofarelationshipbetweenagalaxy’sdistance
fromEarthanditsspeed
Theentireuniversehasapervasiveandconstantbackgroundradiation,
thoughttobethefaintafterglowoftheBigBang
Theamountofhydrogenandheliumgasesintheuniverse
PhotographingtheremnantsofthecosmicsmokeresultingfromtheBigBang
ontheoutskirtsoftheuniversein1989.Thereisanimpressionamong
scientiststhattheamountofmovementresultingfromthisexplosionwillrun
outsomedayandthatwillinevitablyleadtoareflectionandturntheuniverse
intoafoldaccordingtowhatthetheoryofthegreatconvergenceassumes

9. Allah/God
Allahcreatedtheuniverseandthevariousprocessesdrivingphysicaland
biologicalevolution.Theseprocessesthenresultedinthecreationofgalaxies,
oursolarsystem,……
AllahcreatedlifeonEarth
Allahcreatedeverything
Who is the creator of Universe?

10. Agalaxyisahugecollectionofgas,dust,andbillionsofstarsandtheirsolar
systems
Agalaxyisheldtogetherbygravity
TheUniversecontainsbillionsofgalaxies,eachcontainingmillionsorbillions
ofstars,planetsandasteroids,comets,meteors,gases,andsolidandvery
fineparticlesthatareorganizedwitheachotherintheuniverse
Atthelargestscale,galaxiesaredistributeduniformlyandthesameinall
directions,meaningthattheuniversehasneitheranedgenoracenter
Galaxiesdifferandvaryinsize:someofthemaresmall,consistingofonlya
fewmillionstars,someofthemareofmediumsize,andsomeofthemare
large,whichcontainmorethan400billionstars
Galaxiesalsodifferintheirshapes,someofwhicharespherical,semi-
spherical,disc,spiral,fusiform,ellipticalorsemi-elliptical.Thediskshapeis
themostwidespread
Galaxies

11. What galaxy do we live in?
WeliveinoneofthearmsofalargeSpiralgalaxycalledtheMilkyWay.The
Sunanditsplanets(includingEarth)lieinthisquietpartofthegalaxy,about
halfwayoutfromthecenter
TheMilkyWayisthegalaxythatcontainsourSolarSystem,withthename
describingthegalaxy'sappearancefromEarth:ahazybandoflightseenin
thenightskyformedfromstarsthatcannotbeindividuallydistinguishedby
thenakedeye
Radius:52,850lightyears
Age:13.51billionyears
Escapevelocity:550km/s
Numberofstars:100-400billion
Distance:25.6–27.1kly(7.86–8.32kpc)
Constellations:Orion,Sagittarius,Scorpius,Carina,Ara
Ourgalaxy,theMilkyWay,alsohasasupermassiveblackholeinthemiddle
TheMilkyWayGalaxy

12. TheMilkyWayGalaxy

13. Light Year
Thelight-yearisaunitoflengthusedtoexpressastronomicaldistancesand
isequivalenttoabout9.46trillionkilometersor5.88trillionmiles
AsdefinedbytheInternationalAstronomicalUnion,alight-yearisthe
distancethatlighttravelsinvacuuminoneJulianyear
Thespeedoflightinvacuum,commonlydenotedc,isauniversalphysical
constantimportantinmanyareasofphysics.Itsexactvalueisdefinedas
299792458meterspersecond(~300000kmpersecond)

14. Starsareimmenseballsofincandescentgasheldtogetherbygravity
Thecentralcoreofastarisextremelyhotandproducesenergy.Some
ofthisenergyisreleasedasvisiblelight,whichmakesthestarglow
Starscomeindifferentsizes,colors,andtemperatures.OurSun,the
centerofoursolarsystem,isayellowstarofaveragetemperatureand
size
Thesurfacetemperaturesofstarsareveryhigh,reaching30,000°Cin
somespecies,andtheirinternaltemperaturesreachmillionsof
degrees
Thestarsappearintheskyintheformofbrightpoints,andthereason
forthisisthattheyarefarawayfromthesurfaceoftheearth
Gravitybindsstarstogetherintovastgalaxies
Stars

15. Nebula
Anebulaisagiantcloudofdustandgas(hydrogengas,heliumgasandother
ionizedgases)inspace
Somenebulae(morethanonenebula)comefromthegasanddustthrownout
bytheexplosionofadyingstar,suchasasupernova.Othernebulaeare
regionswherenewstarsarebeginningtoform
Themaindifferencebetweengalaxiesandnebulaeareanextremedifferencein
size,aswellastheirbasicstructure.Anebulaisacloudofdustandgas,
usuallytenstohundredsoflightyearsacross.Agalaxyismuchlarger—
usuallythousandstohundredsofthousandsoflightyearsacross

16. Planets
Planetsarelarge,opaquecelestialbodiesorbitingastar(theSun)
aresmallerthanastarbutlargerthananasteroid
Donotproducetheirownlightbutareilluminatedbylightfromthestars
aroundwhichtheyrevolves
Havesufficientmasstogivethemasphericalshape
Arealoneintheirorbits(haveclearedtheirneighborhoodofotherobjects)
Moons
Aresoliddarkbodieslockedinorbitaroundaplanet
Moonsfollowtheplanetsandrevolveintheirorbits
Donotemitlight,butcanreflectlightfromtheneareststar

17. Asteroids
Asteroids,sometimescalledminorplanets,arerocky,airlessremnantsleft
overfromtheearlyformationofoursolarsystemabout4.6billionyearsago
MostofthisancientspacerubblecanbefoundorbitingtheSunbetweenMars
andJupiterwithinthemainasteroidbelt
AsteroidsrangeinsizefromVesta—thelargestatabout329miles(530
kilometers)indiameter—tobodiesthatarelessthan33feet(10meters)
across
ThetotalmassofalltheasteroidscombinedislessthanthatofEarth'sMoon

18. Comets
Cometsarecosmicsnowballsoffrozengases(MethaneandAmmonia),rock
anddustthatorbittheSun.Whenfrozen,theyarethesizeofasmalltown
Cometsarefrozenleftoversfromtheformationofthesolarsystem
Whenacomet'sorbitbringsitclosetotheSun,itheatsupandspewsdust
andgasesintoagiantglowingheadlargerthanmostplanets.Thedustand
gasesformatailthatstretchesawayfromtheSunformillionsofmiles
TherearelikelybillionsofcometsorbitingourSunintheKuiperBeltandeven
moredistantOortCloud

19. Meteoroids, Meteors & Meteorites
They’reallrelatedtotheflashesoflightcalled“shootingstars”sometimes
seenstreakingacrossthesky.Butwecallthesameobjectbydifferentnames,
dependingonwhereitis
Meteoroidsareobjectsinspacethatrangeinsizefromdustgrainstosmall
asteroids.Thinkofthemas“spacerocks.“Thistermonlyapplieswhenthey’re
inspace
Mostarepiecesofother,largerbodiesthathavebeenbrokenorblastedoff.
Somecomefromcomets,othersfromasteroids,andsomeevencomefrom
theMoonandotherplanets
Somemeteoroidsarerocky,whileothersaremetallic,orcombinationsofrock
andmetal

20. Type of Meteorites
WhenmeteoroidsenterEarth’satmosphere(orthatofanotherplanet,like
Mars)athighspeedandburnup,thefireballsor“shootingstars”arecalled
meteors
Whenameteoroidsurvivesatripthroughtheatmosphereandhitstheground,
it’scalledameteorite
MeteoritesmayresembleEarthrocks,buttheyusuallyhaveaburnedexterior
thatcanappearshiny.This“fusioncrust”formsasthemeteorite’souter
surfacemeltswhilepassingthroughtheatmosphere.
Therearethreemajortypesofmeteorites:the"irons,"the"stonys,"andthe
stony-irons.AlthoughthemajorityofmeteoritesthatfalltoEartharestony,
mostofthemeteoritesdiscoveredlongaftertheyfallareirons.Ironsare
heavierandeasiertodistinguishfromEarthrocksthanstonymeteorites

21. IRONMETEORITES:Ironmeteoritesaremadeupofpurenickelandironmetal
withsomeimpuritiessuchasgraphiteandthemineraltroilite
STONYMETEORITES:Stonymeteoritesaremeteoritesmadeofrock,butcan
alsocontainsmallamountsofiron.Therearetwotypesofstonymeteorites;
chondritesandachondrites
STONY-IRONMETEORITES:Stony-Ironmeteoritesarealmostevenmixesof
bothmetallicandrockymaterial

22. Why Do We Care About
Meteorites?

23. The Solar System
TheSolarSystemisthegravitationallyboundsystemoftheSunandthe
objectsthatorbitit,eitherdirectlyorindirectly
OftheobjectsthatorbittheSundirectly,thelargestaretheeight/nineplanets,
withtheremainderbeingsmallerobjects,thedwarfplanetsandsmallSolar
Systembodies
Solarsystem:Asun,planets,moonsandotherobjects
Thesolarsystemalsoincludesasteroidsandcomets
Theshapeofthesolarsystemisellipticalandconsistsofstars(themost
famousofwhichisthesun),planets,moons,asteroids,meteors,comets,
nebulae,gasesandsuspendedfinematerials
ItispartoftheMilkyWaygalaxy.Thesunisthirtythousandlightyearsaway
fromthecenterofthegalaxy
Thisgroupformedabout4.6billionyearsago

24. The Solar System

25. The Sun
TheSunisthelargestobjectwithinoursolarsystem,comprising99.8%ofthe
system'smass.TheSunislocatedatthecenterofoursolarsystem,and
Earthorbits93millionmilesawayfromit.Thoughmassive,theSunstillisn't
aslargeasothertypesofstars.It'sclassifiedasayellowdwarfstar
Ayellowstarofmediumsize,whichisveryclosetotheEarth,soitcanbe
studiedaccuratelyandtheresultsofthisstudycanbeusedtoexplainmany
astronomicalobservationsonotherstars
Thesunisaluminousbodyrotatingarounditselfataspeedof220km/s,
andcompletingonerevolutionarounditscenterinaperiodoftimeof200
millionyearsandcancontaininsideit1,300,000objectsthesizeoftheEarth
Thesurfacetemperatureofthesunreachesabout5700degreesCelsius,the
interiortemperaturereaches14milliondegreesCelsius,andthepressure
reachesonebillionairpressure.Mostoftheearth'sheatisfromthesun
Oursunisoneof300billionstarsintheMilkyWay

27. Planets of the Solar System
ThereareeightplanetsintheSolarSystemaccordingtotheIAUdefinition.In
orderofincreasingdistancefromtheSun,theyarethefourterrestrials,
Mercury,Venus,Earth,andMars,thenthefourgiantplanets,Jupiter,Saturn,
Uranus,andNeptune
Theorderoftheplanetsinthesolarsystem,startingnearestthesunand
workingoutwardisthefollowing:Mercury,Venus,Earth,Mars,Jupiter,
Saturn,Uranus,NeptuneandthenthepossiblePlanetNine.Ifyouinsiston
includingPluto,itwouldcomeafterNeptuneonthelist

28. Planets of the Solar System
TheyaretheplanetsclosetothesunandincludeMercury,Venus,Earthand
Mars
Theyarerelativelysmallandmadeupmainlyofrocksandminerals
1.TerrestrialsorInnerplanetsorrockydwarves
2.OuterplanetsorGasGiants
TheyaretheplanetsfarawayfromthesunandincludeJupiter,Saturn,
Uranus,NeptuneandPluto
TheyarelargeplanetsexceptforPluto
Theyareoftencomposedoflightgaseswithasmallrockycore
Alltheplanetsrevolvearoundthesunina
counterclockwisedirection

29. Moons or natural satellites of the Solar System
UpfirstareMercuryandVenus.Neitherofthemhasamoon
Alotofmoonsornomoonsatall?
MercuryandVenus
WeonEarthhavejustonemoon,butsomeplanetshavedozensofthem.Others
don’thaveany
Whichplanetshavemoons,andwhichdon’t?
Let’sgoinorderfromtheSun
UpnextisEarth,andofcoursewehaveoneconfirmedmoon
Earth(That'sus!)
Marshastwomoons
Mars

30. Uranushas27moonsthatweknowof.Someofthemarehalfmadeofice
Uranus
Lastly,Neptunehas14namedmoons.OneofNeptune'smoons,Triton,isas
bigasdwarfplanetPluto
Neptune
Nextarethegiantouterplanets.Theyhavelotsofmoons.Jupiter,forinstance,
has79moons!(53confirmedand26provisional)
Thesemoonsaresobigyoucanseethemwithjustapairofbinoculars
Jupiter
Saturnhas53moonsthathavebeennamed
Saturnalsohas29moonsawaitingconfirmation.They’reunconfirmed
becausewe’rewaitingtogetmoreinformationaboutthem.Ifallofthese
moonsgetconfirmed,Saturnwillhave82moons.Andthat’snotcounting
Saturn’sbeautifulrings
Saturn

33. Moon of the Earth
TheMoonisEarth’sonlynaturalsatelliteandthefifthlargestmooninthesolar
system
TheMoon’spresencehelpsstabilizeourplanet’swobble,whichhelpsstabilize
ourclimate
TheMoon’sdistancefromEarthisabout240,000miles(385,000km)
Earth'sMoonistheonlyplacebeyondEarthwherehumanshavesetfoot
Thebrightestandlargestobjectinournightsky
TheMoonwaslikelyformedafteraMars-sizedbodycollidedwithEarth
TheMooncausestides
TheMoonhasaverythinatmospherecalledanexosphere
TheMoon’sentiresurfaceiscrateredandpittedfromimpacts

34. Moon of the Earth

35. Motion of the Moon around the Earth
ThemotionofthemoonaroundtheEarthiscalledRevolution
AsiderealmonthisthetimeittakestheMoontocompleteoneorbitaround
Earth.Thistakes,onaverage,27.3days
AlunarmonthisthetimeittakestheMoontopassthroughalloftheMoon
phases,measuredfromoneNewMoontothenextNewMoon.Thistakes,on
average,29.53days

36. Phases or Cycles of the Moon
ThephasesoftheMoonarethedifferentwaystheMoonlooksfromEarthover
aboutamonth
AstheMoonorbitsaroundtheEarth,thehalfoftheMoonthatfacestheSun
willbelitup
ThedifferentshapesofthelitportionoftheMoonthatcanbeseenfromEarth
areknownasphasesoftheMoon
Thedifferenceintheshapeofthemoon(crescent,hump,orfullmoon)isdue
tothelightfallingonitshalffacingthesunandtheangleofitspositionwith
respecttousinhabitantsoftheearth(theangleatwhichweseetheparton
whichthelightfalls
Thehalffacingthesunisalwaysluminous,soifthemoonmovesinitsorbit
aroundtheearth,thenasmallpartofitsluminouspartbeginstoappearinthe
formofacrescentandthenincreasesdayafterdayuntiltheentirebrightpart
isfacingusandweseeitasafullmoon,andthisisafter14daysofThe
movementofthemoonbeganandthengraduallydiminishesuntilit
disappearsafteranother14daysofbeingfullandthushascompleteditscycle

37. What causes the phases of the moon to
change each night?
Thephasesofthemoonarethechangesintheamountofthesurfaceofthe
moonthatarelitupoverthecourseofamonth,asviewedfromearth
BecausethepositionsoftheEarth,Moon,andSunvarythroughoutthecourse
ofthemonth,theamountofthemoon'ssurfacethatwecanseechangesa
littlebiteverynight

38. Eclipse
Aneclipseisanastronomicalevent.Itiswhenoneobjectintheskymoves
intotheshadowofanothersuchobject
Thetermeclipseismostoftenusedtodescribeasolareclipse,whenthe
Moon'sshadowcrossestheEarth'ssurface,oralunareclipse,whentheMoon
movesintotheshadowofEarth
Solar Eclipse Lunar Eclipse

39. Earthisaterrestrialplanet.Itissmallandrocky
Earthsharesthesolarsystemwith7or8planets
Earth,ourhome,isthethirdplanetfromthesun.It'stheonlyplanetknownto
haveanatmospherecontainingfreeoxygen,oceansofwateronitssurface
and,ofcourse,life
Earthisthefifthlargestoftheplanetsinthesolarsystem.It'ssmallerthanthe
fourgasgiants—Jupiter,Saturn,UranusandNeptune—butlargerthanthe
threeotherrockyplanets,Mercury,MarsandVenus
TheEarthisthedensestplanetintheSolarSystem
Earthhasadiameterofroughly8,000miles(13,000kilometers)andisround
becausegravitypullsmatterintoaball.But,it'snotperfectlyround.Earthis
reallyan"oblatespheroid,"becauseitsspincausesittobesquashedatits
polesandswollenattheequator
The Planet Earth

40. EarthhasapowerfulGravitationalForce
EarthhasapowerfulCentrifugalForce
EarthhasapowerfulMagneticForce
TheEarth'sMoltenIronCoreCreatesaMagneticField
TheEarth'ssurfaceisactuallyacombinationofgravitationalandcentrifugal
forces
Watercoversroughly71percentofEarth'ssurface,andmostofthatisinthe
oceans.AboutafifthofEarth'satmosphereconsistsofoxygen,producedby
plants

41. WhileEarthorbitsthesun,theplanetissimultaneouslyspinningonan
imaginarylinecalledanaxisthatrunsfromtheNorthPoletotheSouthPole.It
takesEarth23.934hourstocompletearotationonitsaxis(resultinginday
andnight)and365.26daystocompleteanorbitaroundthesun(resultingin
theseasons)
EarthrotatesarounditsownaxisCounterclockwiseintheNorthPoleand
ClockwiseintheSouthPole
Earth'saxisofrotationistiltedinrelationtotheeclipticplane,animaginary
surfacethroughtheplanet'sorbitaroundthesun.ThismeanstheNorthern
andSouthernhemisphereswillsometimespointtowardorawayfromthesun
dependingonthetimeofyear,andthischangestheamountoflightthe
hemispheresreceive,resultingintheseasons
Earth's orbit

42. Averagedistancefromthesun:92,956,050miles(149,598,262km)
Perihelion(closestapproachtothesun):91,402,640miles(147,098,291km)
Aphelion(farthestdistancefromthesun):94,509,460miles(152,098,233km)
Lengthofsolarday(singlerotationonitsaxis):23.934hours
Lengthofyear(singlerevolutionaroundthesun):365.26days
Equatorialinclinationtoorbit:23.4393degrees
Statistics about Earth's orbit,
according to NASA:

43. GEO-SPHERES
TheareanearthesurfaceoftheearthcanbedividedintoFiveinter-connected
"geo-spheres:"theatmosphere,hydrosphere,lithosphere,magnetosphere,
andthebiosphere

45. Centrifugalforceisanoutwardforce
TheEarthacquiredthispropertyasaresultoftheEarth'srapidrotation
arounditsaxis
SinceEarthrotatesaroundafixedaxis,thedirectionofcentrifugalforceis
alwaysoutwardawayfromtheaxis.Thusitisoppositetothedirectionof
gravityattheequator;atEarth'spolesitiszero
Thispropertyexpelsthecomponentsoftheplanetfromthecentertothe
outside,whichiswhyitiscalledthecentrifugalforce.Itworksagainstthe
forceofgravitythatattractsobjectstowardsthecenter
Thecentrifugalforceissmallatthepolesoftheglobeandlargeattheequator
TheEarth'ssurfaceisactuallyacombinationofgravitationalandcentrifugal
forces
Centrifugal Force

46. Gravityistheforceofattractingobjectstowardstheearthsothatthemasses
ofobjectstendtofallonthesurfaceoftheearthwiththesameforcethat
gravityproduces
Gravityisnotapropertyoftheearthalone.Infact,everyobjectinthe
universeexertsforceoneveryotherobject(So,thereisgravityonjupiterand
otherplanets).Thisforceisknownasthegravitationalforce
Gravitycontrolsallcomponentsoftheuniverse,includingtheEarth.Allthe
planetsofthesolarsystemremainintheirorbitsbytheforceofattraction
betweenthemandthesun
Theearthisuniqueinitsabilitytoattractobjectslocatedwithinthe
gravitationalfieldtowardsitscenterandthereforethispropertyisattributed
totheearthexclusivelyandthesphericalshapeoftheearthresultsfromthe
earth'sattractiontoallitsconstituentpartstotheinside
Gravitational Force

47. TheEarthactslikeahugemagnet.Otherplanetsdonothavethisproperty
Likeabarmagnet,Earthhasadipolarmagneticfield
MagneticfieldlinesflowfromNtoSand
ExtendintospaceandweakenwithdistancefromEarth
CreateashieldaroundEarth(themagnetosphere)
Themagnetosphereistheregionabovetheionospherethatisdefinedbythe
extentoftheEarth'smagneticfieldinspace.Itextendsseveraltensof
thousandsofkilometersintospace,protectingtheEarthfromthecharged
particlesofthesolarwindandcosmicraysthatwouldotherwisestripaway
theupperatmosphere,includingtheozonelayerthatprotectstheEarthfrom
theharmfulultravioletradiation
Magnetic Force

48. Ifweputafree-movingmagneticneedle,ittakesapositionparalleltothe
Earth'smagneticfield,meaningitindicatesthemagneticnorthandsouth.The
magneticnorthandsouthdonotcoincidewiththegeographicnorthand
south.Thereisananglebetweenthemcalled:theangleofmagnetic
declinationandisequalto11.5degrees
Magnetic Declination

49. Themagneticfieldisgeneratedbyelectriccurrentsduetothemotionof
convectioncurrentsofamixtureofmoltenironandnickelintheEarth'souter
core:theseconvectioncurrentsarecausedbyheatescapingfromthecore,a
naturalprocesscalledageodynamo
Therefore,theearthworksasifitisalargeelectricgenerator,whereelectrical
currentsaregeneratedasaresultofthemechanicalenergyresultingfromthe
rapidrotationoftheeartharounditsaxisandtheconvectioncurrentsinits
outercoreandconcomitantmagneticenergygeneration
ThiswillbediscussedindetaillaterwhenwestudytheinterioroftheEarth
Generation of the Magnetic Field