Plate Plate TectonicTectonic

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Name: Name: ______________________________

Date: _________Date: _________

Period: ___Period: ___

What is Plate Tectonics?What is Plate Tectonics?

The theory of the ___________, The theory of the ___________, ____________, and ____________ of the ____________, and ____________ of the earth’s broken crust.earth’s broken crust.

The ___________________( moving pieces) The ___________________( moving pieces) are made from the rigid ________________ are made from the rigid ________________ and fluid ___________________ of the crust and fluid ___________________ of the crust and upper mantle.and upper mantle.

The movement is caused by convection The movement is caused by convection currents of the upper mantle fluid currents of the upper mantle fluid material (magma).material (magma).

15 Major Plates15 Major Plates

ContinentalContinental ArabianArabian AfricaAfrica AustralianAustralian North AmericaNorth America South AmericaSouth America AntarcticaAntarctica EurasiaEurasia IndiaIndia

Oceanic Oceanic PacificPacific CaribbeanCaribbean CoccosCoccos Juan de FucaJuan de Fuca PhilippinePhilippine NazcaNazca ScotiaScotia

Picture of earth’s platesPicture of earth’s plates

Lithospheric PlatesLithospheric Plates

Pieces of the crust and upper mantle Pieces of the crust and upper mantle that movethat move

________________ Crust:________________ Crust: Thicker, but less denseThicker, but less dense Felsic mineralsFelsic minerals Range from 5 to 35 kilometers thickRange from 5 to 35 kilometers thick

_________________ Crust:_________________ Crust: Thinner, but denserThinner, but denser Mafic mineralsMafic minerals Range from 1 to 5 kilometers thickRange from 1 to 5 kilometers thick

The Father of The Father of Continental DriftContinental Drift

Alfred Wegener: German scientistAlfred Wegener: German scientist 1912, proposed a theory that the 1912, proposed a theory that the

earth did not always look the way it earth did not always look the way it does today.does today.

“ “ the continents drifted, or moved, to the continents drifted, or moved, to their present locations over time”their present locations over time”

Many observations/ pieces of Many observations/ pieces of evidence to support this theory:evidence to support this theory:

Picture of Al and Picture of Al and continental driftcontinental drift

Al’s Evidence #1Al’s Evidence #1

The coastlines of The coastlines of western Africa and western Africa and eastern South eastern South America fit America fit together like together like pieces of a jig-saw pieces of a jig-saw puzzle.puzzle.

Al’s Evidence #2Al’s Evidence #2

_________________: _________________: a fresh water a fresh water lizard that lived lizard that lived 270 million years 270 million years ago found only on ago found only on coastal areas of coastal areas of South America and South America and AfricaAfrica

Al’s Evidence #3Al’s Evidence #3

______________________________: ancient fern : ancient fern fossil found in fossil found in Antarctica Antarctica suggested that suggested that this place was this place was warmer in the warmer in the past.past.

Al’s Evidence #4Al’s Evidence #4 Climate Clue: Climate Clue:

Glacier Glacier markings on the markings on the southern southern continents can continents can be connected to be connected to make them one make them one smooth mark smooth mark instead of the instead of the random random directions seen directions seen todaytoday

Al’s Evidence #5Al’s Evidence #5 Rock Clues: Rock Clues:

distinctive distinctive mineral mineral deposits deposits can be can be matched up matched up on several on several continents continents to show one to show one large area large area that was that was connectedconnected

Al’s Evidence #6Al’s Evidence #6

Rock Clues: Rock Clues: Similarity of Similarity of mountain mountain chains and chains and rock rock formations formations can be can be matched up matched up to show one to show one large large formationformation

Al’s Evidence #7Al’s Evidence #7 Volcanoes Volcanoes

and and earthquakearthquakes show es show patterns patterns around around the earth. the earth. Mostly on Mostly on coastlinescoastlines..

Accepted or DeclinedAccepted or Declined

For all of Wegener’s evidence, it did For all of Wegener’s evidence, it did not answer the question “how the not answer the question “how the plates move”.plates move”.

The scientific community did not The scientific community did not ACCEPT his theory.ACCEPT his theory.

Al Wegener died before more Al Wegener died before more concrete evidence was found that concrete evidence was found that gave proof positive to his theorygave proof positive to his theory

New EvidenceNew Evidence 1940’s: with any war come new advances in 1940’s: with any war come new advances in

technologytechnology Planes equipped with Sonar flew back and forth Planes equipped with Sonar flew back and forth

across the Atlantic ocean and recorded magnetic across the Atlantic ocean and recorded magnetic abnormalities.abnormalities.

Recorded the iron minerals in the basalt rock of Recorded the iron minerals in the basalt rock of the ocean floor aligned with polar field of the the ocean floor aligned with polar field of the earth.earth.

The alignment presented itself with alternate The alignment presented itself with alternate bands across the seafloor proving polarity bands across the seafloor proving polarity switched multiple times during the earth’s history.switched multiple times during the earth’s history.

Magnetic FieldMagnetic Field The iron/nickel core of the earth rotates The iron/nickel core of the earth rotates

and produces an electrical field.and produces an electrical field. Due to the interaction of the special Due to the interaction of the special

properties of the mantle, this field properties of the mantle, this field intensifies and produces a shield around intensifies and produces a shield around the earth that protects us from the the earth that protects us from the GAMMA and X-Ray radiation of the sun.GAMMA and X-Ray radiation of the sun.

This field has flipped multiple times in This field has flipped multiple times in the past producing times of Reverse and the past producing times of Reverse and Normal polarity.Normal polarity.

MagneMagnetic tic

FieldField

Age of the Ocean FloorAge of the Ocean Floor More researched proved that the ocean floor More researched proved that the ocean floor

of the Atlantic was younger than of the of the Atlantic was younger than of the continents.continents.

Oldest Continental Rock: _____________ yrs oldOldest Continental Rock: _____________ yrs old Oldest Ocean Rock: _______________ yrs oldOldest Ocean Rock: _______________ yrs old The middle of the ocean has the mid-ocean The middle of the ocean has the mid-ocean

ridge which is :ridge which is : YoungerYounger HotterHotter Higher elevationHigher elevationThan the rock further from the centerThan the rock further from the center

Ocean floorOcean floor

Seafloor SpreadingSeafloor Spreading 1950’s: Robert Dietz theorized that the 1950’s: Robert Dietz theorized that the

continents moved due to the process of the sea continents moved due to the process of the sea floor creating new material in the center and floor creating new material in the center and pushing the continents further apart.pushing the continents further apart.

The process of convection currents inside the The process of convection currents inside the asthenosphere bring less dense, hot molten rock asthenosphere bring less dense, hot molten rock up to the surface and push the older, cooler, and up to the surface and push the older, cooler, and more dense rock apart.more dense rock apart.

Called these areas “Spreading Centers”Called these areas “Spreading Centers” Also called “construction Zones”Also called “construction Zones” There were also “Deconstruction Zones” where There were also “Deconstruction Zones” where

old seafloor was pushed under continents and old seafloor was pushed under continents and recycled. recycled.

Finalizing a TheoryFinalizing a Theory

1960’s: Wegener’s theory became 1960’s: Wegener’s theory became accepted with the help of a accepted with the help of a Princeton geologist: H. HessPrinceton geologist: H. Hess

He took the work of Wegener and He took the work of Wegener and Dietz and came up with the what, Dietz and came up with the what, how, and why of plate movementshow, and why of plate movements

Types of PlatesTypes of Plates

The plates of the earth move The plates of the earth move horizontally across the surfacehorizontally across the surface

They interact and form different They interact and form different boundaries based on their boundaries based on their interactions and their propertiesinteractions and their properties

DIVERGENT DIVERGENT

Two plates that move away from Two plates that move away from each othereach other

Physical Features: Physical Features: Mid ocean ridgeMid ocean ridge Rift ValleyRift Valley Example: Example:

Mid Atlantic Ridge (largest ridge system)Mid Atlantic Ridge (largest ridge system) East Africa Rift Valley (Africa is splitting East Africa Rift Valley (Africa is splitting

apart)apart)

DivergentDivergent

CONVERGENTCONVERGENT

Two plates that move togetherTwo plates that move together Types depend of properties of the Types depend of properties of the

platesplates SubductionSubduction CollisionCollision

ConvergentConvergent

SUBDUCTIONSUBDUCTION One plate is forced under the other due to One plate is forced under the other due to

density differencedensity difference Types:Types:

Continent to Ocean: ocean plate will subduct Continent to Ocean: ocean plate will subduct under the continent. under the continent.

Physical Feature: a sea trench on the coast of the Physical Feature: a sea trench on the coast of the continent and a chain of volcanic mountainscontinent and a chain of volcanic mountains

Example: The Peru Trench and Andes MountainsExample: The Peru Trench and Andes Mountains Ocean to Ocean: the denser plate will be Ocean to Ocean: the denser plate will be

forced under the other forced under the other Physical features: a deep sea trench and an arc of Physical features: a deep sea trench and an arc of

volcanic islandsvolcanic islands Example: Japanese Islands and the Mariana TrenchExample: Japanese Islands and the Mariana Trench

SubductionSubduction

COLLISIONCOLLISION

Two continental plates that crumble Two continental plates that crumble together and form folded mountainstogether and form folded mountains

Example: Himalaya MountainsExample: Himalaya Mountains

TransformTransform

When plates move horizontally past When plates move horizontally past each other with different speeds each other with different speeds and/or directionand/or direction

Physical feature: a fault linePhysical feature: a fault line Example: San Andreas FaultExample: San Andreas Fault

Causes of Plate Causes of Plate MovementMovement

Convection Currents in the mantle are the Convection Currents in the mantle are the driving force behind the plate movements.driving force behind the plate movements.

______________: when the current moves ______________: when the current moves the plate from the mid ocean ridge the plate from the mid ocean ridge utilizing the lower elevation of the sea utilizing the lower elevation of the sea floor.floor.

______________: the sinking edge of the ______________: the sinking edge of the plate is forced down at an subduction plate is forced down at an subduction boundary and drags the rest of the plate boundary and drags the rest of the plate with it.with it.

Convection currentConvection current

Plate Movement and Plate Movement and Continental GrowthContinental Growth

Using Wegener’s evidence, we have Using Wegener’s evidence, we have reconstructed the past and found the reconstructed the past and found the continents fit together like pieces of a continents fit together like pieces of a puzzle to form Pangaeapuzzle to form Pangaea

They do not fit perfectly together due to:They do not fit perfectly together due to: ErosionErosion WeatheringWeathering UpliftingUplifting Volcanic eruptionsVolcanic eruptions Deposition of sedimentsDeposition of sediments

Pangaea Pangaea The giant landmass that started to break up over The giant landmass that started to break up over

200 million years ago.200 million years ago. First broke into 2 large pieces:First broke into 2 large pieces:

Laurasia: Laurasia: North AmericaNorth America EurasiaEurasia GreenlandGreenland

Gondowana:Gondowana: AfricaAfrica South AmericaSouth America AustraliaAustralia AntarcticaAntarctica India India

Then those pieces continued to break apart and Then those pieces continued to break apart and form the present continentsform the present continents

                                                                                        

                        

                    

            

Ancient CoresAncient Cores

______________: The ancient rock ______________: The ancient rock core of Pangaea can be found on all core of Pangaea can be found on all continents.continents.

These cores have been buried under These cores have been buried under secondary continental growth from secondary continental growth from accumulation of deep sea sediments, accumulation of deep sea sediments, igneous rock, river sediments, and igneous rock, river sediments, and terranesterranes

CratonCraton