世界地理-地球的结构与板块构造英文版课件

1、The Structure of the Earth and Plate TectonicsThe Structure of the Earth andStructure of the EarthThe Earth is made up of 3 main layers:CoreMantleCrustInner coreOuter coreMantleCrustStructure of the EarthThe EartThe CrustThis is where we live!The Earths crust is made of:Continental Crust thick (10-7

2、0km)- buoyant (less dense than oceanic crust) - mostly oldOceanic Crust- thin (7 km)- dense (sinks under continental crust)- youngThe CrustThis is where we live世界地理地球的结构与板块构造英文版课件世界地理地球的结构与板块构造英文版课件If you look at a map of the world, you may notice that some of the continents could fit together like

3、pieces of a puzzle.If you look at a map of the woPlate TectonicsThe Earths crust is divided into 12 major plates which are moved in various directions.This plate motion causes them to collide, pull apart, or scrape against each other.Each type of interaction causes a characteristic set of Earth stru

4、ctures or “tectonic” features.The word, tectonic, refers to the deformation of the crust as a consequence of plate interaction.Plate TectonicsThe Earths cruWorld PlatesWorld PlatesWhat are tectonic plates made of?Plates are made of rigid lithosphere.The lithosphere is made up of the crust and the up

5、per part of the mantle.What are tectonic plates made What lies beneath the tectonic plates?Below the lithosphere (which makes up the tectonic plates) is the asthenosphere.What lies beneath the tectonicPlate Movement“Plates” of lithosphere are moved around by the underlying hot mantle convection cell

6、sPlate Movement“Plates” of lithPractical Exercise 1Supercontinents!Practical Exercise 1SupercontiWhat happens at tectonic plate boundaries?What happens at tectonic plateDivergentConvergentTransformThree types of plate boundaryDivergentThree types of plate Spreading ridgesAs plates move apart new mat

7、erial is erupted to fill the gapDivergent BoundariesSpreading ridgesDivergent BounAge of Oceanic CrustCourtesy of Age of Oceanic CrustCourtesy oIceland has a divergent plate boundary running through its middleIceland: An example of continental riftingIceland has a divergent plate There are three sty

8、les of convergent plate boundariesContinent-continent collisionContinent-oceanic crust collisionOcean-ocean collisionConvergent BoundariesThere are three styles of convForms mountains, e.g. European Alps, HimalayasContinent-Continent CollisionForms mountains, e.g. EuropeanHimalayasHimalayasCalled SU

9、BDUCTIONContinent-Oceanic Crust CollisionCalled SUBDUCTIONContinent-OceOceanic lithosphere subducts underneath the continental lithosphereOceanic lithosphere heats and dehydrates as it subsides The melt rises forming volcanismE.g. The AndesSubductionOceanic lithosphere subducts uWhen two oceanic pla

10、tes collide, one runs over the other which causes it to sink into the mantle forming a subduction zone. The subducting plate is bent downward to form a very deep depression in the ocean floor called a trench. The worlds deepest parts of the ocean are found along trenches. E.g. The Mariana Trench is

11、11 km deep!Ocean-Ocean Plate CollisionWhen two oceanic plates collid世界地理地球的结构与板块构造英文版课件Where plates slide past each otherTransform BoundariesAbove: View of the San Andreas transform faultWhere plates slide past each o世界地理地球的结构与板块构造英文版课件Practical Exercise 2Where will the UK be in:1,000 years?1,000,00

12、0 years?1,000,000,000 years?Practical Exercise 2Where willwhats the connection?Volcanoes and Plate Tectonicswhats the connection?VolcanoVolcanism is mostly focused at plate marginsPacific Ring of FireVolcanism is mostly focused at- Subduction - Rifting - HotspotsVolcanoes are formed by:- Subduction

13、- Rifting - HPacific Ring of FireHotspot volcanoesPacific Ring of FireHotspot voHot mantle plumes breaching the surface in the middle of a tectonic plateWhat are Hotspot Volcanoes?Photo: Tom Pfeiffer / The Hawaiian island chain are examples of hotspot volcanoes.Hot mantle plumes breaching thThe tect

14、onic plate moves over a fixed hotspot forming a chain of volcanoes.The volcanoes get younger from one end to the other.The tectonic plate moves over whats the connection?Earthquakes and Plate Tectonicswhats the connection?EarthquAs with volcanoes, earthquakes are not randomly distributed over the gl

15、obeAt the boundaries between plates, friction causes them to stick together. When built up energy causes them to break, earthquakes occur.Figure showing the distribution of earthquakes around the globeAs with volcanoes, earthquakesWhere do earthquakes form? Figure showing the tectonic setting of earthquakesWhere do earthquakes form? FigPlate Tectonics SummaryThe Earth is made up of 3 main layers (core, mantle, crust)On the surface of the Earth are tectonic plates that slowly move