Plate Tectonics - Portal Page Link - We now know that the Earth’s continents and oceans lie on top of Tectonic Plates - which are gradually moving - thanks to convection currents in the Earth’s Mantle. - The Tectonic Plates are moving in the following directions; shown in the Diagram. - As you can see, some of the plates are moving towards each other, and are colliding at the plate boundaries, some are pulling away from each other, and some are moving past each other. - There are 3 types of movement at plate boundaries; - Convergent; collision - Divergent; pulling apart - Transform; sliding past each other - At Convergent boundaries, two things can happen; - When Oceanic Plate & Continental Plate collide, the Oceanic Plate is pushed under the Continental Plate in a process known as ‘subduction’. - When two Continental Plates collide though; the plates push together and fold upwards, as neither is more dense than the other. This forms Mountain Ranges like the Himalayas. - At Divergent Plate boundaries, the two plates are moving away from each other. This creates gaps in the crust that are filled by Magma, which creates new crust as it cools. - The final plate boundary is known as ‘Transform’ - where two plates are sliding past each other. Earthquakes are very common here as the stress causes the crust to buckle & deform. Activity 1 - Mars Bar Plate Tectonics Safety and precautions: - CLEAN UP after yourself - You only get 1 bar, so use it wisely. - No eating in the science lab Introduction: In this lab, you will be simulating plate tectonics with candy bars. The candy bar layers represent earth layers involved in plate tectonics. You will be simulating convergent, divergent, and transform plate motions and you should expect to see different changes in the candy bar shape for each type of motion. The changes in candy bar shape should look similar to geological features found at those kinds of tectonic plate boundaries. 1. Fill out the table below: Mars Bar layer Earth layer Chocolate Mantle Nougat 2. If the earth were a Mars Bar, what would tectonic plates be made out of? 3. Which Earth layer is missing from the Mars Bars model? 4. Which tectonic plate do we live on? 5. What is happening to our tectonic plate? BOUNDARY 1: Unwrap the candy bar. Hold bar with two hands. Using your thumb and index finger gently pull the ends of the Mars bar apart. DO NOT separate bar into two halves 6. Which layer of the Earth ‘cracked’? 7. What type of boundary is modelled by the Mars bar? 8. Why would there be earthquakes at a divergent boundary? BOUNDARY 2 Pick up the Mars bar. Gently push in from the ends of the bar. Place fingers on the edge of the bar, not the top and bottom. Try to keep bar in a straight line. 9: What type of boundary is modelled by the Mars bar? 10: What geologic feature would you expect to form at a boundary where plates push together? BOUNDARY 3 With fingers & thumbs on long edges of bar, slide your right hand forward, pull your left hand back. 11: What type of boundary is modelled by the Mars bar? 12: What might you expect to occur along with this type of boundary? 13: One limitation of this model is that your fingers pulling and pushing is not a natural geologic process. What natural processes might cause the motions of Earth’s plates? How could we represent that in our lab? Activity 2 Using the linked Slideshow from the Plate Tectonics Portal Page, answer the following questions. You can also watch this video to help you further your understanding. 1. Describe the three types of plate boundaries. (3) 2. Explain how convergent plate boundaries create subduction zones and why volcanoes appear here. (4) 3. Explain how convergent plate boundaries create mountains. (3) 4. Explain how divergent plate boundaries create mid-ocean ridges. (2) 5. Explain what divergent plate boundaries cause on land. (1) 6. How is the Earth’s crust recycled? (2) 7. Discuss transform boundaries and how they cause earthquakes. (3) Activity 3 Complete the two linked worksheets in your Science book. Plate Tectonics Folding & Faulting
