Download 8-Plate_Tectonics short

2/13/17
GeologicTime- RelativeAgeDetermination
GeologicTime- RelativeAgeDetermination
A)PrincipleofUniformitarianism =Fornaturaldisasters,
uniformitarianismusedtopredictfutureevents.
Examples?
Whichrocklayerisoldest(bottom,middleortop)?
B)PrincipleofSuperposition =movingupwardthrough
sequenceofsedimentaryrocks,agebecomesyounger
GeologicTime- RelativeAgeDetermination
C)PrincipleofCross-CuttingRelations =Ifigneousintrusion
(orfaultorrivervalley)cutsacrossrocklayers,itisyounger
thanrocklayers
Clickerquestion
Whendidthefaultontherightsideofthediagramoccur?
A. AfterlayerGwaslaiddownbutbeforelayerJwaslaiddown
B. AfterigneousrockMintruded,butbeforelayerKwaslaiddown.
C. AfterlayerKwaslaiddown,butbeforelayerFwaslaiddown.
GeologicTime- RelativeAgeDetermination
D)PrincipleofFossilSuccession =Whenfossilsin
sedimentaryrocksarearrangedbyrelativeage,groupsof
fossilplants+animalshavechangedform(evolved)over
geologictimeindefinite+recognizableorder.
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GeologicTime- RelativeAgeDetermination
GeologicTimeScale
D)PrincipleofFossilSuccession =Groupsoffossilsinrock
canrepresentintervalofgeologictime.
Usingfossils+
radiometricagesof
rocksfromallover
worldresultedin
GeologicTimeScale tableofagesrepresents
Earth'sgeologichistory
GeologicTimeScale- ImportantEvents
AgeofEarth=4.6b.y.(fromageofmeteorites,moonrocks)
Age-datedmeteorite
Age-datedmoonrock
4,400
GeologicTimeScale- ImportantEvents
PreCambrian =Largestblockoftime(88%ofEarthhistory);
lifeevolvedat~3- 3.5b.y.a.(bacteria).Onlysoft-bodied
organismslived,sofewfossilsarepreserved.
GeologicTimeScale- ImportantEvents
PreCambrian/Paleozoicboundary =Appearanceofabundant
animalswithshells;fossilscommonfromthistimeandlater
Extremevolcanism- EarlyPrecambrian
3.5b.y.oldstromatolites (cyanobacteria)
IronFormation- MiddlePrecambrian
AbundantnewlifeinEarlyPaleozoic
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GeologicTimeScale- ImportantEvents
Paleozoic("Oldlife")Era =Trilobites,crinoids,coralreefs,
snails;Appearanceoffish,plants,amphibians,insects
AbundantoceanlifeinPaleozoic
GeologicTimeScale- ImportantEvents
Paleozoic/Mesozoicboundary =Massextinction.Halfofall
familiesoforganismssuddenlydisappeared.
GeologicTimeScale- ImportantEvents
Paleozoic("Oldlife")Era =CarboniferousPeriodinvolved
extensiveforests,swamps(laterbecamecoal).
CarboniferousForestandSwamp
GeologicTimeScale- ImportantEvents
Mesozoic ("Middlelife")Era =Dominanceofreptiles
(dinosaurs),Firstbirds.
DinosaursofMesozoicEra
GeologicTimeScale- ImportantEvents
Mesozoic/Cenozoicboundary =Massextinctionof1/4ofall
familiesoforganisms.Extinctionofalldinosaurs.
GeologicTimeScale- ImportantEvents
Cenozoic("Recentlife")Era =Dominanceofmammals,
Appearanceofhumans,currentlyexperiencingmass
extinction.
MammalsofCenozoic
Mesozoic/CenozoicMassExtinction
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WebExercise1– Duetwodaysago
Exam#1
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MondayFebruary27th
7:15PM
141LoomisHallforA- N
151LoomisHallforO– Z
#8PlateTectonics
• 2-pointpenaltyforevery24-hourperiodthatassignmentislate.
NoWebExercise#1isacceptedafter1pmonFriday
• After~5PMFriday,WebExercise#1scoreswillbevisibleinIL
CompassGradebook;atthesametime,feedback,includingyour
answersandthecorrectanswers,willbeavailableinILCompass
Questions?ContacttheTA
WebExercise#2- StartsFriday2/10;due2/17
• WebExercise#2(Earthquakes)willbeavailableontheGEOL118
ILCompassWebsiteonFriday
• WebExercise#2willincludequestionsbasedoninformationin
HazardCity software(MasteringGeology WebSite)andthe
Internet.
• YoumustbuyaccesstoMasteringGeologyandRegister(see
classwebpagesforinstructions)
https://www.youtube.com/watch?v=uLah
VJNnoZ4
Startat2:00
PlateTectonics
PlateTectonicstheory =outerportionofEarthconsistsof
numberofthickslabsofrock(tectonicplates)thatslowly
movearoundglobe;Inmapview,tectonicplatecanconsist
entirelyofoceaniccrustorbothoceanic+continentalcrust.
PlateTectonics
Incross-section,tectonicplate=lithosphere - ~cool,outer
rigidlayerwhererockscanbreak,~100kmthick,includes
entirecrust+outerpartofmantle;belowlithosphereis
asthenosphere - layerof~hot,weakrockthatflows,from
~100- ~300kmindepth,onlymantlerock.
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PlateTectonics
TheasthenosphereisNOT
alayerofliquid
PlateTectonicBoundaries
Threetypesofplateboundaries:Divergent,Convergent,
Transform
PlateTectonicBoundaries
I)Divergentboundary - whereplatesmoveapart.Defined
byoceanicridge - underseavolcanicmountain rangeof
non-explosivevolcanoes whereoceaniccrust (basalt)is
produced duetorisingmoltenrock (whichgeneratesminor
EQ'sonly);cooledrockmoveslaterallyawayfromridge
PlateTectonicBoundaries
Tectonicplateboundariesaredefinedbyzonesoffrequent
earthquakes.Volcanoesandmountainrangesarealso
commonatplateboundaries.
PlateTectonicBoundaries
I)Divergentboundary - whereplatesmoveapart.
PlateTectonicBoundaries
http://earthguide.ucsd.edu/eoc/teachers/t_tectonics/p_se
afloorspreading.html
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PlateTectonicBoundaries- Divergent
Divergentboundary/oceanicridgewrapsaroundglobe
PlateTectonicBoundaries- Divergent
Examples=
Mid-Atlanticridge,
Iceland
Betterviewedin
GoogleEarth
Oceanicridgeshowninred
PlateTectonicBoundaries
II)Convergentboundary - whereplatescometogether;
definedbysubduction zone,whereoldoceanlithosphereis
subducted (descendsbackintomantle+melts)+destroyed
PlateTectonicBoundaries- Convergent
Manyearthquakes (EQs,majorandminor)asrocksgrind
pasteachother
PlateTectonicBoundaries- Convergent
Oceanic trench (deeplineartrough)=wheresubduction
begins.Ascrust+mantlemelt(partially),produces
explosivevolcaniceruptions +volcanicmountains
PlateTectonicBoundaries- Convergent
Oceanic trench (deeplineartrough)=wheresubduction
begins.Ascrust+mantlemelt(partially),produces
explosivevolcaniceruptions +volcanicmountains
SeeGoogleEarthtrenches
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PlateTectonicBoundaries- Convergent
Examples=Andesmountains(ocean/continent
convergence),Japan(ocean/oceanconvergence)
PlateTectonicBoundaries- Convergent
Ifalloceanlithosphereissubducted,thereis
continent/continentcollision;continentscan'tsubduct
(~lowdensity),creatingtremendousmountainrange(and
major+minorEQs)butnovolcanoes(e.g.,Himalayas).
PlateTectonicBoundaries- Transform
Wheretwoplatesgrindpasteachotherwithhorizontal
motion;definedbymajorfault (transformfault);not
creatingnewcrustordestroyingoldcrust(norockmelts),
sonomountainsorvolcanoes;grindingtwoblocksofcrust
pasteachother,solotsofEQ's(major+minor).
PlateTectonicBoundaries- Convergent
MarginofPacificOcean="RingofFire"(lotsofEQs+
volcanoes),thereisconvergentboundaryatmostlocations
PlateTectonicBoundaries
- Convergent
Continent/ContinentCollisionZone
Example=Himalayas
PlateTectonicBoundaries- Transform
Example=SanAndreasFault,CA.
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Clickerquestion
Whichtypeofplateboundaryusuallygenerates
explosivevolcanoes?
A. Divergentplateboundary
B. Convergentplateboundary
C. Transformplateboundary
D. Alloftheabove
E. Noneoftheabove
PlateTectonicMotion- Speed
Platesmoveatspeedsof2- 10cm/yr (measuredbyageof
oceancrustandbyaccuratepositionsoflocationsonEarth
fromlaser-satellitedata)
PlateTectonicMotion- OverGeologicTime
Platesmoveatspeedsof2- 10cm/yr;Overgeologictime,
Earth'ssurfaceisconstantlychangingplace
Clickerquestion
Whichtypeofplateboundarydoesnotoftengenerate
large,damagingearthquakes?
A. Divergentplateboundary
B. Convergentplateboundary
C. Transformplateboundary
Skippednext4slides
PlateTectonicMotion- FutureProjections
Continentpositions50m.y.infuture
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PlateTectonicMotion- FutureProjections
Californiawon’tfallintoPacificOcean
PlateTectonic
MotionFuture
Projections
California
PlateTectonicTheory- Importance
PlateTectonicTheory- Importance
WhyisPlateTectonicstheoryrelevanttoNaturalDisasters?
WhyisPlateTectonicstheoryrelevanttoNatural
Disasters?
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