Q1M6 POOSIBLE CAUSES of Plate movements.pptx

earth science

1. Quarter 1 – Module 6: Possible Causes of Plate Movement

2. Content Standard: The learners demonstrate an understanding of the relationship among the locations of volcanoes, earthquake epicenters, and mountain ranges . MELC: Describe the possible causes of plate movement (S10ES – Ia-j-36.5)

3. Guide questions What are the two types of plates? How do plates move? What geologic features are formed? What causes the movement of the plates?

4. Possible Causes of Plate Movement Convection Current Ridge Push Slab Pull

5. Possible Causes of Plate Movement There are three forces working to move the plates. 1. Convection Current 2. Ridge Push 3. Slab Pull

6. Possible Causes of Plate Movement There are three forces working to move the plates. 1. Convection Current 2. Ridge Push 3. Slab Pull

7. Possible Causes of Plate Movement Heated mantle material is shown rising from deep inside the mantle, while cooler mantle material sinks, creating a convection current. It is thought that this type of current is responsible for the movements of the plates of Earth's crust. Convection Current

8. Possible Causes of Plate Movement This process can also take place in the Earth’s mantle. The temperature difference in the mantle causes the movement of the molten materials. The hot, less dense materials rise and the cooler, denser materials sink. This process of rising and sinking molten materials is called MANTLE CONVECTION. Convection Current

9. Mechanisms for Plate Motion forces cause two plates to pull apart on the surface. The lithosphere rocks SLIDE away from the ridge, due to gravity, down the sloping asthenosphere. The asthenosphere is less dense than the rocks above it making it possible for the cooled lithosphere rocks above it to slide down the slope of the asthenosphere. Ridge-Push

10. Mechanisms for Plate Motion The process continues in the ridge where new molten magma wells up and becomes the new lithosphere. This force that the rocks exert at the ridge to spread the lithosphere is called RIDGE PUSH. Ridge-Push It refers to the pushing force that plates experience as they slide down the raised asthenosphere underneath Mid Ocean Ridges.

11. Mechanisms for Plate Motion forces pull the plates down. The force that the sinking plate exerts on the rest of the plate is called SLAB PULL. The edge of the subducting plate is much colder and heavier than the mantle, so, it continues to sink pulling the rest of the plate connected to it. Slab-Pull

12. Mechanisms for Plate Motion As the plate moves away from the diverging boundary, it ages and cools, thus becoming much denser. The cold, dense lithosphere then sinks down into the asthenosphere (at subduction zones) and "pulls" the rest of the plate along with it. Slab-Pull

13. Mechanisms for Plate Motion Occur only in Mid-oceanic Ridges. Slab-Pull and Push Ridge

14. Theories of Plate Tectonic Movements Seafloor Spreading Theory p roposed by Harry Hess (1960) is a geologic process in which tectonic plates—large slabs of Earth's lithosphere—split apart from each other. is the mechanism by which new oceanic lithosphere is created at and moves away from divergent plate boundaries.

15. Theories of Plate Tectonic Movements Seafloor Spreading Theory Mantle convection is the slow, churning motion of Earth’s mantle. Convection currents carry heat from the lower mantle and core to the lithosphere. Convection currents also “recycle” lithospheric materials back to the mantle. Seafloor spreading occurs at divergent plate boundaries.

16. Theories of Plate Tectonic Movements GUIDE CARD Seafloor Spreading Theory As tectonic plates slowly move away from each other, heat from the mantle’s convection currents makes the crust more plastic and less dense. The less-dense material rises, often forming a mountain or elevated area of the seafloor. Eventually, the crust cracks. Hot magma fueled by mantle convection bubbles up to fill these fractures and spills onto the crust. This bubbled-up magma is cooled by frigid seawater to form igneous rock. This rock (basalt) becomes a new part of Earth’s crust.

17. Theories of Plate Tectonic Movements GUIDE CARD Seafloor Spreading Theory Mid-Ocean Ridges Seafloor spreading occurs along mid-ocean ridges— large mountain ranges rising from the ocean floor. The Mid-Atlantic Ridge separates the North American plate from the Eurasian plate, and the South American plate from the African plate.

18. Theories of Plate Tectonic Movements GUIDE CARD Seafloor Spreading Theory The East Pacific Rise is a mid-ocean ridge that runs through the eastern Pacific Ocean and separates the Pacific plate from the North American plate, the Cocos plate, the Nazca plate, and the Antarctic plate. The Southeast Indian Ridge marks where the southern Indo-Australian plate forms a divergent boundary with the Antarctic plate.  

19. Theories of Plate Tectonic Movements GUIDE CARD Seafloor Spreading Theory The Mid-Atlantic Ridge, for instance, is a slow-spreading center. It spreads 2-5 centimeters (.8-2 inches) every year and forms an ocean trench about the size of the Grand Canyon. The East Pacific Rise, on the other hand, is a fast-spreading center. It spreads about 6-16 centimeters (3-6 inches) every year.

20. Seafloor Spreading Theory

21. 1. What geologic features formed at divergent plate boundaries? mid-ocean ridges convergent rifts seafloor separations none of these are correct

22. What causes ridge-push to occur? A. hot buoyant mantle beneath the ridge B. large quantities of volcanic rock near the ridge C. Both of these are correct D. Neither of these is correct

23. 3. What is ridge-push? A. A force causing plates to move away from divergent plate boundaries B. A force causing plates to dive into the mantle C. A force causing plates to slide past one another D. A force that rips plates apart

24. 4. The mantle of Earth is made partly of magma. When magma rises and sinks, this is called ______________. ion current a hot spot a volcanic eruption a convection current

25. Seafloor Spreading Theory 1. What causes ridge-push to occur? hot buoyant mantle beneath the ridge large quantities of volcanic rock near the ridge Both of these are correct Neither of these are correct . Scientists think that convection currents that move the plates flow in Earth's answer choices Continental crust Oceanic crust mantle outer core

26. 5. When the force of gravity pulls a lithospheric plate downward and away from a ridge pushing it toward a trench. Sea Floor Spreading Subduction Ridge Push Slab Pull