1. Do Now Silently & Independently answer the questions on the chart on your desk. 1.What is continental drift? 2.Why didn’t people believe continental drift at first? 3.How do you think continental drift and the layers of the earth work together?

2. Seafloor Spreading February 17, 2016

3. Goal Use what we know about the layers of the earth and continental drift to help Wegener prove his theory. Reminder: the problem with Wegener’s theory was that he could not explain how the continents move. Today, we will explain one way the continents move!

4. What do we already know about the structure of the earth? Continental Crust Oceanic Crust

5. Review: The crust is the outer most layer of the earth. There are 2 types of crust: Oceanic Crust: crust that makes up the ocean floor Continental Crust: crust that makes up continents

6. Mountains Under the Ocean!

7. Mid Ocean Ridges: a mountain that is on the ocean floor. Formed from cooling magma https://www.youtube.com/watch?v=sgDM6m0lUGY

8. There are cracks in Mid-Ocean Ridges

9. Rift: Deep cracks in the middle of mid-ocean ridges. Magma pours out of rifts. Rift Valley: a valley that forms in a mid-ocean ridge due to hardened magma

10. There are canyons under water!

11. Deep Ocean Trenches: a canyon under water where ocean floor sinks and melts back into the mantle Subduction: where old oceanic crust is forced back down into an ocean trench https://www.youtube.com/watch?v=v7rHMy52WKQ

12. Seafloor Spreading is the process that creates this all! Seafloor Spreading: the process that forms new seafloor by adding crust to the ocean floor. Seafloor Spreading Process: 1.Begins at the mid ocean ridge 2.Magma from the mantle hardens along the mid ocean ridge, forming a strip of rock 3.As new crust forms in the middle, it pushes the older crust to the outside of the trench. 4.As the plates move, the older crust goes back into the mantle

13. Seafloor Spreading Animations http://emvc.geol.ucsb.edu/forteachers/flashmovies/Spreading.s wf https://www.youtube.com/watch?v=f-nIb8JkFrg https://www.youtube.com/watch?v=ryrXAGY1dmE

14. Go back to your Do Now Go back to your Do Now and fill in the “after” column. Fill it in with the correct answers based on what you learned today. If your answer was already detailed, then rewrite it in the “after” column