1. The Earth’s Oceans and Plate Tectonics Oceanography Unit #1

2. Our Earth 5.0 and 7.0 billion years old  Earth is between 5.0 and 7.0 billion years old.  Crust  Mantle  Outer core  Inner core

3. The Earth’s Crust  Asthenosphere  Asthenosphere – an area of weakened crust and molten upper mantle.  Lithosphere  Lithosphere – the rigid hardened crust.  Crustal types:  Oceanic Crust  Oceanic Crust – found beneath the ocean basins  Continental Crust  Continental Crust – found beneath the continents and margins

4. Crustal Comparsions

5. Earth’s Hydrosphere 4.0 billion years old.  Oceans are approx. 4.0 billion years old. 71%  Oceans cover approx. 71% of the earth’s surface.  Water?  Oceans = 97.22%  Glaciers = 2.15%  Ground water =.62%  Atmosphere, lakes, rivers, etc. = <.01%

6. The Ocean Basins Southern Ocean Southern Ocean – combination of the most southern Pacific, southern Atlantic, and southern Indian; surrounding Antarctica.

7. Ocean Topography  Continental shelf – submerged edge of the continent; most biologically active.  Continental slope – descends from shelf down to the deep sea-floor.  Continental rise – sediments that accumulate at the slope’s base.  Abyssal plains – most of the ocean’s floor; avg. depth = 4.0 km.  Seamounts – submarine volcanoes  Trenches – found at base of slope; depth >6.0 km.

8. Mid-Ocean Ridge System  “Spreading centers”; crustal expansion.  Largest geographical feature on planet. 65,000 km.  Total length is over 65,000 km.  “Spreading centers”; crustal expansion.  Largest geographical feature on planet. 65,000 km.  Total length is over 65,000 km.

9. Plate Boundaries 1. Divergent: Two or more plates are directed away from each other. Mid-ocean ridge system Numerous volcanic eruptions and earthquakes. Volcanic islands such as Iceland, Azores, and Ascencion. 2. Lateral : Two plates slip past each other. San Andreas Fault (CA). Numerous large earthquakes

10. Plate Boundaries 1. Convergent: Crustal plates are directed towards each other. i. Two continental plates collide: Build up of crust in to mountain ranges. Himalayan Mountains ii. One continental plate and one oceanic plate collide: subduction zones. Creates subduction zones. Japan Islands, New Zealand, Andes

11. Subduction Zone

12. Hotspots  Areas where magma punches a hole in thin, weak crust above; Stationary.  Hawaiian-Emperor island chain: