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Bell Work: 10/24/13 Write the question, full answer, and justify why you chose your answer. Work on your Earth’s Layers Foldable when you are finished with bell work. Objectives 27. Movements of Earth’s Major Plates ►Can I differentiate among the characteristics of earth’s three layers? (SPI 0707.7.4) ►Can I recognize that lithospheric plates on the scale of continents and oceans continually move at rates of centimeters per year. (SPI 0707.7.5) ►Can I describe the relationship between plate movements and earthquakes, mountain building, volcanoes, and sea floor spreading. (SPI 0707.7.6) ►Shifting Plates Choice Boards Think, Pair, Share … Come up with an explanation to the following question, pair up with your elbow partner, & share: ►How do we know so much about the mantle and the core? Question… How do we know so much about the mantle and the core? ►We can study magma on the Earth’s surface from volcanic eruptions. Also, seismic waves, or vibrations produced from earthquakes, travel at different speeds through the Earth. Their speed depends on the density and composition of the material they pass through. Traveling through a solid will go faster than through a liquid. How did this knowledge help scientists figure out what state each layer is in? Restless Continents ► Look at pg. 400! ► In the early 1900s, ___________ ___________ Alfred Wegener wrote about his hypothesis of ____________ continental ______, drift arguing that all the continents were once joined together in a single landmass and have drifted apart. ► He proposed that the continents plowed through ocean floor, driven by the spin of the Earth. ► Continental drift is the hypothesis that states that continents once formed a single the _____________ ______________, broke up, and drifted to their landmass present locations. Pangaea ► Wegener thought that all of the present continents were once joined in a __________ single, huge continent called Pangaea ______________. ► Pangaea is Greek for “all Earth” ______________. You try it! Make Pangaea with the pieces of continents at your group. Look at the map. At your group, discuss the following questions. You have 2 minutes. 1. What evidence supports Wegener’s theory? 2. Since all dinosaurs cannot swim, explain how the same fossil can be found on all continents. Challenging Question… Think, Pair, Share… ► Based on what you know about the plates, how would you prove Wegener’s theory to be true today? Tracking Tectonic Plate Motion ► Today, scientists use a system of satellites called global positioning system or GPS. ► Radio signals are continuously beamed from satellites to GPS ground stations, which record the exact distance between the satellites and the ground stations. ► Over time, these distances change slightly. **The movement is measured in centimeters per year. Composition of Earth’s Plates ► Wegener thought that more than continents were plate moving. According to the theory of _________ _________, tectonics Earth’s lithosphere is divided into tectonic plates that move around on the asthenosphere. boundary is a place where tectonic plates ► A ___________ touch. ► ____________Convergent boundary formed by the collision of two lithospheric plates Divergent ► ____________boundary between two tectonic plates that are moving away from each other Transform ► ____________boundary between tectonic plates that are sliding past each other horizontally Proving Wegener Wrong ► The older term "continental drift" is not quite accurate -- both continents and oceanic crust move. ► We now know that Wegener's theory was wrong in one major point: continents do not plow through the ocean floor. Instead, both continents and ocean floor form solid plates, which "float" on the asthenosphere, the underlying rock that is under such tremendous heat and pressure that it behaves as an extremely viscous liquid. 2 Minute Journal Write a two minute journal giving evidence on how Wegner’s Continental Drift theory could possibly be true, but also discuss the flaws behind his theory. Events associated with movements of earth’s major plates: ► Sea-floor spreading ► Mountain building ► Earthquakes ► Volcanoes Bell Work: 10/25/13 Please write the question, answer, and explain why you chose that answer (justify). Have your Earth’s Layers foldable open on your desk & turn in your questions to the inbox. Objectives 27. Movements of Earth’s Major Plates ►Differentiate among the characteristics of earth’s three layers. (SPI 0707.7.4) ►Recognize that lithospheric plates on the scale of continents and oceans continually move at rates of centimeters per year. (SPI 0707.7.5) ►Describe the relationship between plate movements and earthquakes, mountain building, volcanoes, and sea floor spreading. (SPI 0707.7.6) ►Shifting Plates Choice Boards Events associated with movements of earth’s major plates: ► Sea-floor spreading ► Mountain building ► Earthquakes ► Volcanoes Sea-Floor Spreading ► ► ► Mid-ocean __________, ridges ____________ or underwater mountain Sea-floor spreading takes chains, are where ____________ ___________ place. Divergent boundaries are formed when plates move away from each other. Sea-floor spreading is the process by which new magma Lithosphere (or crust) forms as __________ oceanic ____________________ rises toward the surface and solidifies. tectonic __________ plates As ___________ move away from each other, the sea floor spreads apart and magma fills the gap. Draw a picture of Sea Floor Spreading. Mountain Building Mountains ► ______________ exist because tectonic plates are continually ______________ around and moving colliding with one another. ___________ ► The Andes Mountains in South America formed where two tectonic plates converge or collide. compression ► When tectonic plates undergo ________________ tension or ____________, they form mountains. Volcanoes ► ► ► ► ► Tectonic plate boundaries are likely places for volcanoes to form. _____________ ________ _____ which are The _________ Ring of _________, Fire plate boundaries surrounding the Pacific Ocean, contains nearly _____ 75% of the world’s active volcanoes. About _____ 80% of active volcanoes on land form where plates ______________, and about ______ collide 15% form where plates ____________. separate At these plate boundaries it is possible for magma _____________ to form and travel to the surface. What about the volcanoes that do not form at plate boundaries? How do they form? Look at page 466. Earthquakes ► ► ► ► ► ► ► The study of earthquakes is called ________________. seismology Most earthquakes take place near the edges of tectonic ___________. plates __________ As tectonic plates push, pull, or slip past each other, stress increases along breaks in the Earth’s crust, or faults ___________. In response to this stress, rock in the plates _______________. deforms Elastic _______________ deformation __________ leads to earthquakes. It’s like a stretched rubber band, you can only stretch rock so far before it breaks. When the rock breaks, it releases energy ________________. This energy is released in the form of seismic waves. 2 Minute Journal “Why is it important to me and to the future of our planet to learn as much as we can about the movement of plates and what effects they have?” Shifting Plates Choice Board ► You and a partner will complete one mandatory topic and one topic of choice from the Shifting Plates Choice Board. ► Along with researching these topics, you and your partner will choose a product to create for each topic. ► You may only use each product once. You must use the sites on my portaportal to research your topics.