Presentation on theme: "Preview Section 1 Inside the Earth Section 2 Restless Continents"— Presentation transcript:
1Preview Section 1 Inside the Earth Section 2 Restless Continents Plate TectonicsPreviewSection 1 Inside the EarthSection 2 Restless ContinentsSection 3 The Theory of Plate TectonicsSection 4 Deforming the Earth’s CrustConcept Mapping
2Section 1 Inside the Earth Question of the DayIf you journeyed to the center of the Earth, what doyou think you would see along the way?Draw an illustration of the journey for your QOD.
3Section 1 Inside the Earth ObjectivesIdentify the layers of the Earth by their chemical composition.Identify the layers of the Earth by their physical properties.Describe a tectonic plate.Explain how scientists know about the structure of Earth’s interior.
4The Composition of the Earth Section 1 Inside the EarthThe Composition of the EarthThe Earth is divided into three layers.CrustMantleCoreCrust - the thin and solid outermost layer of the Earth above the mantle.Crust is 5 to 100 km thick, and is the thinnest layer of the Earth.
5The Composition of the Earth, continued Section 1 Inside the EarthThe Composition of the Earth, continuedTwo types of crust—continental (land) and oceanic (ocean).Oceanic crust is thinner and denser than continental crust.
6The Composition of the Earth, continued Section 1 Inside the EarthThe Composition of the Earth, continuedMantle - the layer of rock between the Earth’s crust and core.The mantle is much thicker than the crust, it makes up about 2/3 of Earth.We have never dug down that deep, so scientists must draw conclusions about what the mantle is made of and other physical properties from the Earth’s surface.
7The Composition of the Earth, continued Section 1 Inside the EarthThe Composition of the Earth, continuedCore - the central part of the Earth below the mantle.The core makes up about one-third of Earth’s mass.Scientists think that the Earth’s core is made mostly of iron.
9The Physical Structure of the Earth Section 1 Inside the EarthThe Physical Structure of the EarthThe Earth is divided into five physical layers:The lithosphereThe asthenosphereThe mesosphereThe outer coreThe inner coreEach layer has its own set of physical properties.
10Physical Structure of the Earth, continued Section 1 Inside the EarthPhysical Structure of the Earth, continuedLithosphere – the solid, outer layer of the Earth that consists of the crust and the rigid upper part of the mantle.The lithosphere is divided into pieces that are called tectonic plates.
11Physical Structure of the Earth, continued Section 1 Inside the EarthPhysical Structure of the Earth, continuedAsthenosphere - the soft layer of the mantle on which the tectonic plates move.The asthenosphere is made of solid rock that flows very slowly.
13Physical Structure of the Earth, continued Section 1 Inside the EarthPhysical Structure of the Earth, continuedMesosphere - is the strong, lower part of the mantle between the asthenosphere and the outer core.The prefix meso- means “middle.”
14Physical Structure of the Earth, continued Section 1 Inside the EarthPhysical Structure of the Earth, continuedEarth’s core is divided into two parts.The outer core is liquid and is right under the mantle.The inner core is solid iron and is the center of the Earth.
16Section 1 Inside the Earth Tectonic PlatesTectonic Plate – a block of lithosphere that consists of the crust and the rigid, outermost part of the mantle.These plates make the Earth look covered in puzzle pieces.
17Tectonic Plates, continued Section 1 Inside the EarthTectonic Plates, continuedA Giant Jigsaw Puzzle Each tectonic plate fits together with the tectonic plates that surround it.The lithosphere is like a jigsaw puzzle. The tectonic plates are like the pieces of the puzzle.
18Tectonic Plates, continued Section 1 Inside the EarthTectonic Plates, continuedA Tectonic Plate Close-Up The following Visual Concept presentation shows the Earth’s major tectonic plates and how they fit together.The presentation also illustrates what a tectonic plate might look like if you could lift it out of its place.
19Tectonic Plates, continued Section 1 Inside the EarthTectonic Plates, continuedTectonic plates “float” on the asthenosphere.The plates bump into one another when they move.
20Mapping the Earth’s Interior Section 1 Inside the EarthMapping the Earth’s InteriorSince we can’t dig in the Earth how do we know what is there?Scientists measure speeds of seismic waves that travel through the Earth’s interior during earthquakes.By using seismographs, scientists have learned that the Earth is made of different layers.
21Question of the Day What is meant by the following statement: Section 2 Restless ContinentsQuestion of the DayWhat is meant by the following statement:“The United States is moving westward.”From what you know about geology and plate tectonics explain if you believe this statement to be true or false.
22Objectives Describe Wegener’s hypothesis of continental drift. Section 2 Restless ContinentsObjectivesDescribe Wegener’s hypothesis of continental drift.Explain how sea-floor spreading provides a way for continents to move.Describe how new oceanic lithosphere forms at mid-ocean ridges.Explain how magnetic reversals provide evidence for sea-floor spreading.
23Continental Drift Hypothesis Section 2 Restless ContinentsContinental Drift HypothesisContinental drift - the hypothesis that states that continents once formed a single landmass, broke up, and drifted to their present locations.
24Section 2 Restless Continents The Breakup of PangaeaIt was theorized that all of the present continents were once joined in a single, huge continent he called Pangaea.Pangaea is Greek for “all earth.”Pangaea existed about 245 million years ago.
25Section 2 Restless Continents Sea-Floor SpreadingEvidence supporting continental drift hypothesis comes from sea-floor spreading.Sea-floor spreading - the process by which new oceanic lithosphere forms as magma rises toward the surface and solidifies.
26Sea-Floor Spreading, continued Section 2 Restless ContinentsSea-Floor Spreading, continuedMid-ocean ridges are underwater mountain chains that run through Earth’s ocean basins where sea-floor spreading takes place.
28Sea-Floor Spreading, continued Section 2 Restless ContinentsSea-Floor Spreading, continuedSome of the most important evidence of sea-floor spreading comes from magnetic reversals recorded in the ocean floor.Molten rock at the mid-ocean ridge contains tiny grains of magnetic minerals that act like compasses.
29Sea-Floor Spreading, continued Section 2 Restless ContinentsSea-Floor Spreading, continuedWhen the Earth’s magnetic field reverses, the magnetic mineral grains align in the opposite direction. The new rock records the direction of the Earth’s magnetic field.
30Question of the Day If the sea floor is spreading an average of 4 cm a Section 3 The Theory of Plate TectonicsQuestion of the DayIf the sea floor is spreading an average of 4 cm ayear, how many years did it take New York and the west coast of Africa to reach their current locations, 6,760 km apart?Calculate your answer in your science journal.
31Objectives Describe the three types of tectonic plate boundaries. Section 3 The Theory of Plate TectonicsObjectivesDescribe the three types of tectonic plate boundaries.Describe the three forces thought to move tectonic plates.Explain how scientists measure the rate at which tectonic plates move.
32Tectonic Plate Boundaries Section 3 The Theory of Plate TectonicsTectonic Plate BoundariesAs scientists’ understanding of mid-ocean ridges and magnetic reversals grew, a theory was formed to explain how tectonic plates move.Plate tectonics is the theory that explains how large pieces of the Earth’s outermost layer, called tectonic plates, move and change shape.
33Tectonic Plate Boundaries, continued Section 3 The Theory of Plate TectonicsTectonic Plate Boundaries, continuedA boundary is a place where tectonic plates touch.All tectonic plates share boundaries with other tectonic plates.The type of boundary depends on which direction the tectonic plates move.
34Tectonic Plate Boundaries, continued Section 3 The Theory of Plate TectonicsTectonic Plate Boundaries, continuedThree types of boundaries:Convergent BoundariesDivergent BoundariesTransform Boundaries
35Tectonic Plate Boundaries, continued Section 3 The Theory of Plate TectonicsTectonic Plate Boundaries, continuedConvergent boundary – the boundary formed by the collision of two lithospheric plates.What happens at convergent boundaries depends on the kind of crust at the leading edge of each tectonic plate.
37Tectonic Plate Boundaries, continued Section 3 The Theory of Plate TectonicsTectonic Plate Boundaries, continuedDivergent boundary – the boundary between two tectonic plates that are moving away from each other.New sea floor forms at divergent boundaries. Sea-Floor Spreading.
38Tectonic Plate Boundaries, continued Section 3 The Theory of Plate TectonicsTectonic Plate Boundaries, continuedTransform boundary – the boundary between tectonic plates that are sliding past each other horizontally.The San Andreas Fault in California is an example of a transform boundary.
40Causes of Plate Movement Section 3 The Theory of Plate TectonicsCauses of Plate MovementWhat causes the motion of tectonic plates?Tectonic plates move because of changes in the density in the asthenosphere.The following Visual Concept presentation examines three possible driving forces of tectonic plate motion.
41Tracking Plate Movement Section 3 The Theory of Plate TectonicsTracking Plate MovementTectonic plate movements are so slow and gradual that you can’t see or feel them.Tectonic plate movement is measured in centimeters per year.Scientists use a system of satellites called the global positioning system (GPS) to measure the rate of tectonic plate movement.