Lesson 6 Date: 1/19 LT: I can describe the processes that change Earths surface. Sponge: Where are earthquakes most likely to occur? To do Agenda Engage What do you think the squiggly line in the middle of the Atlantic Ocean represents? Engage The ridge is part of the longest mountain range in the world, which lies under the ocean. It includes a rift valley along the edge that marks the plate boundary. When scientists discovered this, they wondered how it got there.and came up with seafloor spreading! Lets make a model of seafloor spreading Copy and answer the questions below your sponge! 1. What feature of the ocean floor does the center slit stand for? Copy and answer the questions below your sponge! 1. What feature of the ocean floor does the center slit stand for? Mid Ocean Ridge Copy and answer the questions below your sponge! 2. What do the side slits stand for? And what is happening at the side slits? Copy and answer the questions below your sponge! 2. What do the side slits stand for? And what is happening at the side slits? The side slits show trenches where the plates are sinking back in to the mantle and melting. Copy and answer the questions below your sponge! 3. How does the ocean floor close to the center differ from the ocean floor near the sides? Copy and answer the questions below your sponge! 3. How does the ocean floor close to the center differ from the ocean floor near the sides? The closer to the center, the younger the ocean floor is. Copy and answer the questions below your sponge! 4. What do the stripes represent? Why it important that your model have an identical pattern of stripes on both sides of the center slit? Copy and answer the questions below your sponge! 4. What do the stripes represent? Why it important that your model have an identical pattern of stripes on both sides of the center slit? They represent areas of crust made at different times. They need to be copies of each other since they were made at the same time. Copy and answer the questions below your sponge! 5. How do difference in density and temperature provide some of the force needed to cause sea- floor spreading and subduction? Temperature differences cause convection currents. These currents cause molton rock to erupt through the mid-ocean ridge. As material erupts, the sea floor spreads, cools, and becomes denser. Denser material sinks back into the mantle when it reaches a trench. Copy this drawing below your sponge! THE PROOF-----SEAFLOOR SPREADING Intro An American scientist named Harry Hess proposed the seafloor spreading theory in The Sea floor spreading theory states that new ocean crust is being created at mid- ocean ridges (which are large mountain chains underwater) and destroyed at deep- sea trenches. This is proof that the plates are moving along on a conveyor belt so Wegners idea on continent drift was correct. The force responsible for driving or moving the plates is _____________________. Convection Currents occur within the mantle of the earth when hot magma rises and cool magma sinks convection currents Animation Magma, because it is hotter and less dense, is forced up towards the ocean floor cooling off when it touches water. When the magma hardens, a small amount of new ocean floor is added to the Earths crust. As more magma rises and cools it pushes the new sea floor away from the ridge. This process is called sea floor spreading. PROOF THAT THE SEA FLOOR IS SPREADING 1. The oldest ocean floor rocks ever found are 180 million years old. Remember the Earth is 4.6 billion years old. This proves that ocean floor is being destroyed therefore all ocean floor rocks are young compared to the age of Earth. 2. The rocks closest to the ocean ridge were younger than the rocks found further from the ridge. This means that new rocks are formed at the ridges and push the older rocks away from the ridge. AMAZING EARTH SCIENCE FACTS 1. ____________________is created at mid oceanic ridges. 2. Age of rock ____________ as distance from ridge increases (____________ rock is at the ridge). New sea floor increases youngest 3.__________________ __________________ drive plate movement. Convection currents If time More EQ Videos quake-montagequake-montage -earthquake-earthquake Brainpop: Ocean Floor Lesson 6 Date: 1/20 LT: I can explain the process of sea-floor spreading in terms of cycling matter. Sponge: The rock closest to the Mid Atlantic Ridge is ___________ (choose youngest or oldest). To do Check HW Review Seafloor Spreading: https://www.youtube.com/watch?v=GyMLlLxbfa4 https://www.youtube.com/watch?v=GyMLlLxbfa4 Seafloor Spreading Reading NB 114 NB A is a mid ocean ridge which is formed from molten material coming through a crack in the oceans crust. NB A is a mid ocean ridge which is formed from molten material coming through a crack in the oceans crust. 2. Point B shows seafloor spreading. This process happens when magma from the mantel reaches the crust, constantly adding new ocean floor. NB A is a mid ocean ridge which is formed from molten material coming through a crack in the oceans crust. 2. Point B shows seafloor spreading. This process happens when magma from the mantel reaches the crust, constantly adding new ocean floor. 3. Old crust is pushed farther apart. NB Point B shows seafloor spreading. This process happens when magma from the mantel reaches the crust, constantly adding new ocean floor. 3. Old crust is pushed farther apart sonar mapping of ocean floor 2. pillow shaped rocks that form when magma cools quickly 3. older rock is farther from the ridge NB Old crust is pushed farther apart sonar mapping of ocean floor 2. pillow shaped rocks that form when magma cools quickly 3. older rock is farther from the ridge 5. C is a trench showing subduction. Old crust is sinking in to the mantle and being melted again. NB sonar mapping of ocean floor 2. pillow shaped rocks that form when magma cools quickly 3. older rock is farther from the ridge 5. C is a trench showing subduction. Old crust is sinking in to the mantle and being melted again. 6. The processes are constantly recycling Earths surface. NB C is a trench showing subduction. Old crust is sinking in to the mantle and being melted again. 6. The processes are constantly recycling Earths surface. 7. Deep-ocean trench NB C is a trench showing subduction. Old crust is sinking in to the mantle and being melted again. 6. The processes are constantly recycling Earths surface. 7. Deep-ocean trench 8. seafloor spreading NB C is a trench showing subduction. Old crust is sinking in to the mantle and being melted again. 6. The processes are constantly recycling Earths surface. 7. Deep-ocean trench 8. seafloor spreading 9. subduction NB Deep-ocean trench 8. seafloor spreading 9. subduction 10. The matter that makes up Earths crust s constantly being moved from the mantle to the crust and then melting back to the mantle. So, it is recycled! Seafloor Spreading + Continental Drift Seafloor spreading is more proof for continental drift! https://huzzaz.com/collection/geoscience- processes?hzv= https://huzzaz.com/collection/geoscience- processes?hzv=316406 Journal Check Put your name on the top. Number your notecard 1 to 5. Journal Check 1. Which LANDFORM would be found at A? 2. Which LANDFORM would be found at B? Journal Check 3. Which rock would be youngest? Journal Check 4. Which statement is correct? A. Rock that makes up the ocean floor lies in a pattern of stripes. B. The pattern of stripes is different on both sides of the ocean ridge. C. There is no evidence of patterns on the ocean floor. Journal Check 5. Seafloor spreading supports Wegeners ideas. True or false?