The Theory of Plate The Theory of Plate

TectonicsTectonics

And Continental DriftAnd Continental Drift

Essential QuestionsEssential Questions

►►What is the Theory of Continental Drift?What is the Theory of Continental Drift?

►►What is the Theory of Plate Tectonics?What is the Theory of Plate Tectonics?

►►What are the names of the plates?What are the names of the plates?

Practical Exercise 1Practical Exercise 1Supercontinents!Supercontinents!

►► If you look at a map of the world, you may notice that some of tIf you look at a map of the world, you may notice that some of the he

continents could fit together like pieces of a puzzle.continents could fit together like pieces of a puzzle.

The Birth of a TheoryThe Birth of a Theory

Earth Revealed SeriesEarth Revealed Series

►►While watching the video, complete the While watching the video, complete the

worksheet provided. This is to be put into worksheet provided. This is to be put into

your portfolio.your portfolio.

►►http://www.learner.org/vod/vod_window.hthttp://www.learner.org/vod/vod_window.ht

ml?pid=316ml?pid=316

►►19 19 minsmins

Global Tectonics: Global Tectonics:

Competing Theories Competing Theories

►►While watching the video, complete the While watching the video, complete the

worksheet provided. This is to be placed worksheet provided. This is to be placed

into your portfolio.into your portfolio.

►►http://learning.aliant.net/Player/ALC_Player.http://learning.aliant.net/Player/ALC_Player.

asp?ProgID=VEA_TECTONICSasp?ProgID=VEA_TECTONICS

►►22 22 minsmins

Global Tectonics: Global Tectonics:

Competing TheoriesCompeting Theories

►►After the video, answer the After the video, answer the ““after the after the

programprogram”” questions. These are due in 1 questions. These are due in 1

week.week.

The Development of the TheoryThe Development of the Theory

�Wegener’s continental drift hypothesis stated that the continents had once been joined to form a single supercontinent.�Wegener proposed that the supercontinent, Pangaea, began to break apart 200 million years ago and form the present landmasses.

�Wegner proposed this theory in 1912

Breakup of PangaeaBreakup of Pangaea

Continental DriftContinental Drift

����Evidence�The Continental Puzzle�Matching Fossils

�Fossil evidence for continental drift includes several fossil organisms found on different landmasses.

�Rock Types and Structures�Rock evidence for continental exists in the form of several mountain belts that end at one coastline, only to reappear on a landmass across the ocean.

�Ancient Climates

•

Problems With WegenerProblems With Wegener’’s Theorys Theory

►►No mechanism for movement of continentsNo mechanism for movement of continents

►►Wind and currents could possibly move Wind and currents could possibly move

fossilsfossils

►►Theory was not accepted by scientistsTheory was not accepted by scientists

Continental DriftContinental Drift continuedcontinued

� A New Theory Emerges�Wegener could not provide an explanation of exactly what made the continents move. �New technology lead to findings which then lead to a new theory called plate tectonics.

Testing Plate TectonicsTesting Plate Tectonics

����Evidence for Plate Tectonics�Paleomagnetism is the natural remnant

magnetism in rock bodies; this permanent

magnetization acquired by rock can be used to

determine the location of the magnetic poles at

the time the rock became magnetized.�Normal polarity—when rocks show the same magnetism as the present magnetism field�Reverse polarity—when rocks show the opposite magnetism as the present magnetism field�The discovery of strips of alternating polarity, which lie as mirror images across the ocean ridges, is among the strongest evidence of seafloor spreading.

Testing Plate Tectonics Testing Plate Tectonics

continuedcontinued�Earthquake Patterns

�Scientists found a close link between deep-focus earthquakes and ocean trenches.�The absence of deep-focus earthquakes along the oceanic ridge system was shown to be consistent with the new theory.

�Ocean Drilling�The data on the ages of seafloor sediment confirmed what the seafloor spreading hypothesis predicted.�The youngest oceanic crust is at the ridge crest, and the oldest oceanic crust is at the continental margins.

�Hot Spots�A hot spot is a concentration of heat in the mantle capable of producing magma, which rises to Earth’s surface; The Pacific plate moves over a hot spot, producing the Hawaiian Islands.�Hot spot evidence supports that the plates move over the Earth’s surface.

Time to PauseTime to Pause……

►►Plate Tectonics Theory assignment.Plate Tectonics Theory assignment.

Plate TectonicsPlate Tectonics

►► The EarthThe Earth’’s crust is divided into plates which s crust is divided into plates which move in various directions.move in various directions.

►► This plate motion causes them to collide, pull This plate motion causes them to collide, pull apart, or scrape against each other.apart, or scrape against each other.

►► Each type of interaction causes a characteristic Each type of interaction causes a characteristic set of Earth structures or set of Earth structures or ““tectonictectonic”” features.features.

►► The word, tectonic, refers to the deformation The word, tectonic, refers to the deformation of the crust as a consequence of plate of the crust as a consequence of plate interaction.interaction.

World PlatesWorld Plates

Major PlatesMajor Plates

►► North American PlateNorth American Plate�� covering most of covering most of North America, Greenland, Cuba, North America, Greenland, Cuba, Bahamas, and parts of Siberia and Iceland. Bahamas, and parts of Siberia and Iceland.

�� It extends eastward to the MidIt extends eastward to the Mid--Atlantic Ridge and Atlantic Ridge and westward to the westward to the CherskyChersky Range in eastern Siberia. Range in eastern Siberia.

►► Eurasian PlateEurasian Plate�� covering most of covering most of North America, Greenland, Cuba, North America, Greenland, Cuba, Bahamas, and parts of Siberia and Iceland. Bahamas, and parts of Siberia and Iceland.

�� It extends eastward to the MidIt extends eastward to the Mid--Atlantic Ridge and Atlantic Ridge and westward to the westward to the CherskyChersky Range Range in eastern Siberia. in eastern Siberia.

►► Pacific PlatePacific Plate�� is an oceanic is an oceanic tectonic plate beneath the Pacific Oceantectonic plate beneath the Pacific Ocean

�� at 103 million square at 103 million square kilometreskilometres it is the largest of all it is the largest of all tectonic plates tectonic plates

Major Plates continuedMajor Plates continued……►► South American PlateSouth American Plate

�� includes the includes the continent of South America and also a continent of South America and also a sizeable region of the Atlantic Ocean seabed extending sizeable region of the Atlantic Ocean seabed extending eastward to the Mideastward to the Mid--Atlantic Ridge. Atlantic Ridge.

►► Antarctic PlateAntarctic Plate�� includes the includes the continent of Antarctica and extending continent of Antarctica and extending outward under the surrounding oceansoutward under the surrounding oceans. .

►► Australian PlateAustralian Plate�� includes the includes the continent of Australia and surrounding continent of Australia and surrounding ocean, and extends northwest to include the Indian ocean, and extends northwest to include the Indian subcontinent and subcontinent and adjacent waters. adjacent waters.

►► African PlateAfrican Plate�� includes the includes the continent of Africacontinent of Africa, as well as oceanic crust , as well as oceanic crust which lies between the continent and various which lies between the continent and various surrounding ocean ridges. surrounding ocean ridges.

Minor PlatesMinor Plates

►► NazcaNazca PlatePlate�� an oceanic an oceanic tectonic plate in the eastern Pacific Ocean tectonic plate in the eastern Pacific Ocean basin off the west coast of South Americabasin off the west coast of South America. .

►► CarribeanCarribean PlatePlate�� mostly mostly oceanic tectonic plate underlying Central America oceanic tectonic plate underlying Central America and the Caribbean Sea off the north coast of South and the Caribbean Sea off the north coast of South America. America.

►► CocosCocos PlatePlate�� is an oceanic is an oceanic tectonic plate beneath the Pacific Ocean tectonic plate beneath the Pacific Ocean off the west coast of Central America off the west coast of Central America

►► Juan de Fuca PlateJuan de Fuca Plate�� generated from the generated from the Juan de Fuca Ridge Juan de Fuca Ridge

Minor Plates continuedMinor Plates continued……

►► Arabian PlateArabian Plate

�� consists mostly of the consists mostly of the Arabian peninsula; it extends Arabian peninsula; it extends

northward to Turkeynorthward to Turkey. .

►► Indian PlateIndian Plate

�� includes the includes the subcontinent of India and a portion of the subcontinent of India and a portion of the

basin under the Indian Ocean basin under the Indian Ocean

►► Philippine PlatePhilippine Plate

�� comprising most of the country of the comprising most of the country of the PhilippinesPhilippines. .

►► Scotia PlateScotia Plate

�� an oceanic an oceanic tectonic plate tectonic plate

Time to PauseTime to Pause……

►►Complete the worksheet Complete the worksheet –– Tectonic Plate Tectonic Plate

NamesNames

What are tectonic plates made of?What are tectonic plates made of?

►►Plates are Plates are

made of rigid made of rigid

lithospherelithosphere..

The lithosphere is

made up of the

crust and the upper

part of the mantle.

Plate MovementPlate Movement

►► ““PlatesPlates”” of lithosphere are moved around by of lithosphere are moved around by

the underlying hot mantle convection cellsthe underlying hot mantle convection cells

How can EarthHow can Earth’’s plates move? s plates move?

►►The plates of the lithosphere float on The plates of the lithosphere float on

the top of the the top of the asthenosphereasthenosphere

►►Convection currents rise in the Convection currents rise in the

asthenosphereasthenosphere and spread out beneath and spread out beneath

the lithospherethe lithosphere►►Geologists believe this causes plate movementGeologists believe this causes plate movement

Practical Exercise 2Practical Exercise 2

Where will Where will ““xx”” be in:be in:

1,000 years?1,000 years?

1,000,000 years?1,000,000 years?

1,000,000,000 years?1,000,000,000 years?