1. Sea-floor Spreading Section 1.4

2. Mid-Ocean Ridges In the mid 1900’s scientists discovered that the ocean floor is not flat. huge mountains deep trenches. like a zipper or baseball stitching

3. Mid-ocean ridge At the mid-ocean ridge new Earth crust is added. https://www.youtube.com/watch?v=MmMX83diwl0

4. Sea-floor spreading The sea floor spreads outward like a conveyor belt. Video

5. The sea floor spreads apart along both sides of the mid-ocean ridge. Sea-floor spreading https://www.youtube.com/watch?v=oXYAdzmwQsc https://www.youtube.com/watch?v=MmMX83diwl0

6. Evidence for Sea-floor spreading Molten Material - pillow like features that only form when molten material cools quickly VIDEO

7. Evidence for Sea-floor spreading Magnetic Stripes – When rocks form they freeze the magnetic orientation. The ocean surface is striped at regular intervals of opposite magnetism. http://www.geolsoc.org.uk/Plate-Tectonics/Chap3-Plate-Margins/Divergent/Mid-Atlantic-Ridge

8. Evidence for Sea-floor spreading Core samples – Further away you get from the mid-ocean ridge the older the rocks become.

9. Subduction at Trenches Subduction - Process where ocean floor sinks beneath a continental crust. Deep ocean trenches are formed where oceanic crust meets the continental crust.