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Lesson 3 Reading Guide - KC What is the theory of plate tectonics? What are the three types of plate boundaries? Why do tectonic plates move? The Theory.

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Presentation on theme: "Lesson 3 Reading Guide - KC What is the theory of plate tectonics? What are the three types of plate boundaries? Why do tectonic plates move? The Theory."— Presentation transcript:

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2 Lesson 3 Reading Guide - KC What is the theory of plate tectonics? What are the three types of plate boundaries? Why do tectonic plates move? The Theory of Plate Tectonics

3 Lesson 3 Reading Guide - Vocab plate tectonics lithosphere divergent plate boundary transform plate boundary convergent plate boundary The Theory of Plate Tectonics

4 Lesson 3 Reading Guide - Vocab subduction convection ridge push slab pull The Theory of Plate Tectonics

5 Lesson 3-1 The theory of plate tectonics, proposed in the late 1960s, states that Earth’s surface is made of rigid slabs of rock, or plates, that move with respect to each other.plate tectonics Plate tectonics suggests that Earth’s surface is divided into large plates of rigid rock and each plate moves over Earth’s hot and semiplastic mantle. The Plate Tectonics Theory

6 Lesson 3-1 The Plate Tectonics Theory (cont.) What is plate tectonics?

7 Lesson 3-1 Geologists use the word tectonic to describe the forces that shape Earth’s surface and the rock structures that form as a result. The cold and rigid outermost rock layer of the Earth is called the lithosphere.lithosphere The lithosphere is made up of the crust and the solid, uppermost mantle. The Plate Tectonics Theory (cont.)

8 Lesson 3-1 Earth’s Tectonic Plates

9 Lesson 3-1 The lithosphere is thin below mid-ocean ridges and thick below continents. Earth’s tectonic plates are large pieces of the lithosphere that fit together like the pieces of a giant jigsaw puzzle. The layer of Earth below the lithosphere, called the asthenosphere, is so hot that it behaves like a plastic material and enables Earth’s plates to move. The Plate Tectonics Theory (cont.)

10 Lesson 3-2 plastic Science Use capable of being molded or changing shape without breaking Common Use any of numerous organic, synthetic, or processed materials made into objects The Plate Tectonics Theory (cont.)

11 Lesson 3-2 A divergent plate boundary forms where two plates separate.divergent plate boundary When the seafloor spreads at a mid- ocean ridge, lava erupts, cools, and forms new oceanic crust. Divergent plate boundaries can also exist in the middle of a continent, where they pull continents apart and form rift valleys. Plate Boundaries

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13 Lesson 3-2 A transform plate boundary forms where two plates slide past each other.transform plate boundary As they move past one another, the plates can get stuck and stop moving. Stress builds up where the plates are stuck until they eventually break and suddenly move apart, resulting in a rapid release of energy as earthquakes. Plate Boundaries (cont.)

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15 Lesson 3-2 Convergent plate boundaries form where two plates collide.Convergent plate boundaries The denser plate sinks below the more buoyant plate in a process called subduction. subduction The area where a denser plate descends into Earth along a convergent plate boundary is called a subduction zone. Plate Boundaries (cont.)

16 Lesson 3-2 Plate Boundaries (cont.) subduction from Latin subductus, means “to lead under, removal”

17 Lesson 3-2 When an oceanic plate and a continental plate collide, the denser oceanic plate subducts under the edge of the continent, creating a deep ocean trench and a line of volcanoes above the subducting plate on the edge of the continent. When two continental plates collide, neither plate is subducted, and mountains form from uplifted rock. Plate Boundaries (cont.)

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20 Lesson 3-2 Plate Boundaries (cont.) What are the three types of plate boundaries?

21 Lesson 3-3 Scientists can measure how fast continents move using a network of satellites called the Global Positioning System. Because plates are rigid, tectonic activity occurs where plates meet. Evidence for Plate Tectonics

22 Lesson 3-3 Volcanoes form where plates separate along a mid-ocean ridge or continental rift or collide along a subduction zone. Mountains can form where two continents collide. Evidence for Plate Tectonics (cont.)

23 Lesson 3-3 Notice the relationship between earthquake epicenters, volcanoes, and plate boundaries.

24 Lesson 3-3 Evidence for Plate Tectonics (cont.) How are earthquakes and volcanoes related to the theory of plate tectonics?

25 Lesson 3-4 Earth’s plates move because the asthenosphere moves underneath the lithosphere. Convection is the circulation of material caused by differences in density.Convection Hot mantle material rises upward and comes in contact with Earth’s crust. Plate Motion

26 Lesson 3-4 As the mantle cools, it becomes denser and then sinks, forming a convection current. Convection currents in the asthenosphere act like a conveyor belt moving the lithosphere above it. There are three forces that interact to cause plate motion: basal drag, ridge push, and slab pull. Plate Motion (cont.)

27 Lesson 3-4 Plate Motion (cont.) What causes convection?

28 Lesson 3-4 Basal drag refers to how convection currents in the asthenosphere circulate and drag the lithosphere like a conveyor belt. Rising mantle material at mid-ocean ridges creates the potential for plates to move away from the ridge with a force called ridge push.ridge push Plate Motion (cont.)

29 Lesson 3-4 As a slab, or dense plate, sinks, it pulls on the rest of the plate with a force called slab pull. slab pull

30 Lesson 3-5 Plate tectonics has become the unifying theory of geology, but several unanswered questions remain. Why is Earth the only planet in the solar system that has plate tectonic activity? Why do some earthquakes and volcanoes occur far away from plate boundaries? A Theory in Progress

31 Lesson 3-5 What forces dominate plate motion? What will scientists study next? This is a 3-D image of seismic wave velocities from a new technique called anisotropy.

32 Lesson 3 - VS Tectonic plates are made of cold and rigid slabs of rock. Mantle convection— the circulation of mantle material due to density differences—drives plate motion.

33 Lesson 3 - VS The three types of plate boundaries are divergent, convergent, and transform boundaries.

34 Lesson 3 – LR1 A.semiplastic B.lithosphere C.tectonic D.mantle What word do geologists use to describe the forces that shape Earth’s surface?

35 Lesson 3 – LR2 A.seafloor B.lithosphere C.biosphere D.hydrosphere Which of these is made up of the crust and the solid, uppermost mantle?

36 Lesson 3 – LR3 A.convergent plate boundary B.transform plate boundary C.new plate boundary D.divergent plate boundary What type of boundary forms where two plates separate?

37 Lesson 3 - Now 5.Continents drift across a molten mantle. 6.Mountain ranges can form when continents collide. Do you agree or disagree?


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