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DO NOW Friday November 18th 1. What causes movement of the crustal plates? 2. Which layer of the Earth is most dense? Least dense? Explain how you know. TODAY’S PLAN •I can list the layers of the Earth. •I can describe the composition of the layers of the Earth. •I can explain what causes movement of the crustal plates. •I can relate density to the order of Earth’s layers. TODAYS DO •Kahoot Review •Earth’s layers quiz •Data Notebooks •Discussion of Plate boundaries and movement Quiz Expectations • Please be quiet at all times. • Do your best. (Eyes on own paper.) • Finished? – Turn your paper in to the front table – Get out your data notebook, graph your last test grade and your over all class average (from your progress report). – Write a goal for your next test grade and How you are going to reach that goal. – Raise your hand and leave your folder open so I can check it. DO NOW Tuesday November 22nd • Sign out a ChromeBook. • Go to my 8th Grade Science Page. • Click on the first folder under Files/Links called Plate Tectonics WebQuest • Finish your Plate Tectonics WebQuest and turn in to black basket. • Pick up Plate Tectonics Gizmo WS from table. • Click on Gizmos Website on my 8th grade page. • Login and complete Plate Tectonics Gizmo DO NOW Monday November 28th 1. What is plate tectonics? Explain using what you have learned so far. TODAY’S PLAN •I can define plate tectonics. •I can identify types of plate boundaries. •I can explain the movement of plates at the different types of boundaries •I can relate movement of plates to features/events that occur at the plate boundaries. TODAYS DO •Hand out iLearn@Home assignments •Complete graphic organizer about plate boundaries • https://www.youtube.com/watch?v=0m WQs1_L3fA The Structure of the Earth and Plate Tectonics Structure of the Earth Mantle • The Earth is made up of 4 main layers: – Crust – Mantle – Outer Core – Inner Core Outer core Inner core Crust The Crust • This is where we live! • The Earth’s crust is made of: Continental Crust Oceanic Crust - thick (10-70km) - buoyant (less dense than oceanic crust) - mostly old - thin (~7 km) - dense (sinks under continental crust) - young What is Plate Tectonics? • If you look at a map of the world, you may notice that some of the continents could fit together like pieces of a puzzle. Plate Tectonics • The Earth’s crust is divided into 12 major plates which are moved in various directions. • This plate motion causes them to collide, pull apart, or scrape against each other. • Each type of interaction causes a characteristic set of Earth structures or “tectonic” features. • The word, tectonic, refers to the deformation of the crust as a consequence of plate interaction. World Plates What are tectonic plates made of? • Plates are made of rigid lithosphere. The lithosphere is made up of the crust and the upper part of the mantle. What lies beneath the tectonic plates? • Below the lithosphere (which makes up the tectonic plates) is the asthenosphere. Plate Movement • “Plates” of lithosphere are moved around by the underlying hot convection cells in the astenosphere. DO NOW Tuesday November 19th 1. What type of boundary results in the formation of mountains? 2. What type of boundary results in the formation of deep ocean trenches and volcanoes? 3. What type of boundary results in the formation of the mid ocean and sea floor spreading? 4. What type of boundary results in the formation of a fault ilne and earthquakes? TODAY’S PLAN •I can define plate tectonics. •I can identify types of plate boundaries. •I can explain the movement of plates at the different types of boundaries •I can relate movement of plates to features/events that occur at the plate boundaries. TODAYS DO •Finish/review discussion of Plate Boundaries •Oreo Plate Tectonics •Kahoot review of plate boundaries Three types of plate boundary • Divergent • Convergent • Transform Divergent Boundaries • Plates spreading apart (“Rifting”) – As plates move apart new material is erupted to fill the gap – (2 ocean plates) Results in sea floor spreading and forms the mid ocean ridge. – (2 continental plates) Results in volcanoes Sea-Floor Spreading • Where two ocean plates are diverging (moving apart), molten magma erupts, forming underwater mountains under the ocean called the mid-ocean ridge. • As the oceans plates move further and further apart, new ocean floor is continuously added. This is called seafloor spreading. Red = youngest crust Age of Oceanic Crust Courtesy of www.ngdc.noaa.gov Convergent Boundaries • Plates colliding together • May form mountains, trenches, and/or volcanoes Convergent Boundaries • There are three styles of convergent plate boundaries – Continent-continent collision – Continent-oceanic crust collision – Ocean-ocean collision Continent-Continent Collision • Forms mountains, e.g. European Alps, Himalayas Continent-Oceanic Crust Collision • Called SUBDUCTION • Forms volcanoes and deep ocean trenches Subduction • Oceanic lithosphere subducts underneath the continental lithosphere • Oceanic lithosphere heats and melts forming magma • The magma rises forming volcanoes • E.g. The Andes Ocean-Ocean Plate Collision • When two oceanic plates collide, one runs over the other which causes it to sink into the mantle forming a subduction zone. • The subducting plate is bent downward to form a very deep depression in the ocean floor called a deep ocean trench. • The worlds deepest parts of the ocean are found along trenches. – E.g. The Mariana Trench is 11 km deep! • Volcanoes are also formed resulting in the formation of islands. Transform Boundaries • Where plates slide past each other • Earthquakes frequently occur Above: View of the San Andreas transform fault Real World Examples • Divergent Plate Boundary • Convergent Plate Boundary • Transform Plate Boundary Iceland: An example of continental rifting • Iceland has a divergent plate boundary running through its middle= many volcanoes Himalayas: continent-continent convergent boundary Volcanoes and Plate Tectonics… …what’s the connection? Pacific Ring of Fire Volcanoes form all along the oceanocean convergent plate boundaries (subduction zones). Ocean-Continent Convergence The Andes Mountains/ volcanoes Transform Plate Boundary The San Andreas Fault California, USA Volcanoes are formed by: - Subduction (Continental-Ocean and Ocena-Ocean Plate Convergence) - Rifting (Divergent Plates) - Hotspots Earthquakes and Plate Tectonics… …what’s the connection? • As with volcanoes, earthquakes are not randomly distributed over the globe Figure showing the distribution of earthquakes around the globe • At the boundaries between plates, friction causes them to stick together. When built up energy causes them to break, earthquakes occur. Plate Tectonics Summary • The Earth is made up of 4 main layers (inner and outer core, mantle, and crust) • On the surface of the Earth are tectonic plates that slowly move around the globe • Plates are made of crust and upper mantle (lithosphere) • There are 2 types of plates (crust). • There are 3 types of plate boundaries. • Volcanoes and Earthquakes are closely linked to the margins (or boundaries) of the tectonic plates. Pacific Ring of Fire Hotspot volcanoes What are Hotspot Volcanoes? • Hot mantle plumes breaching the surface in the middle of a tectonic plate The Hawaiian island chain are examples of hotspot volcanoes. Photo: Tom Pfeiffer / www.volcanodiscovery.com The tectonic plate moves over a fixed hotspot forming a chain of volcanoes. The volcanoes get younger from one end to the other. Where do earthquakes form? Figure showing the tectonic setting of earthquakes