1. Oceans

2. 71% of Earth’s surface Pacific – largest, deepest Atlantic Indian – mostly in Southern Hemisphere Arctic – smallest, shallowest, entirely in Northern Hemisphere

3. Ocean Floor Continental margins, Ocean basin floor, Mid-ocean ridge

4. Mid-Ocean Ridges Near the center of ocean basins Formed by diverging plate boundaries Zone of new crust formation Collectively the longest mt. range on Earth - 42,000 miles Much quiet volcanic activity – magma rises to fill space and cool as plates spread apart.

5. Mid-Ocean Ridges

6. Hydrothermal Vents Seawater seeps into crust, gets superheated & saturated with minerals. Ejected through gaps along mid-ocean ridge When it hits the cold ocean water, minerals get deposited in large masses – copper, silver, gold, iron, zinc, sulfur, & others. Source of energy & nutrients that supports large colonies of life far from surface & sunlight.

7. Hydrothermal Vents

9. Continental Margins Transition zone between continents & ocean basin floor In Atlantic, not associated with plate boundaries, so few earthquakes or volcanoes. In Pacific, ocean plates forced beneath continental plates, lots of earthquake & volcanic activity – Ring of Fire

10. Continental Margins Continental shelf Gently sloping zone from shore. Shallow (exposed during ice ages) Lots of minerals, oil, & natural gas. Lots of sediment, especially near mouths of rivers. Zone of sedimentary rock formation Lots of fish/ feeding areas.

11. Continental Margins Continental slope Steeper than shelf Boundary between continental crust & ocean crust Submarine canyons cut into shelf from slope, form when turbidity currents (dense, sediment- rich water) flow downhill.

12. Continental Margins Continental Rise Gentler incline, farther offshore and not as steep as cont. slope.

13. Ocean Basin Floor Between continental margin & mid-ocean ridge

14. Ocean Basin Floor Trenches Long, narrow, deepest part of oceans Formed at converging plate boundaries, ocean plate is denser & sinks beneath continental plate Lots of earthquakes & volcanoes

15. Ocean Basin Floor Abyssal plains Very flat, very deep Formed as sediments settle out or get deposited by turbidity currents, fill in deeper parts of ocean floor.

16. Ocean Basin Floor Seamounts – peaks of underwater, growing volcanoes, form islands if they break the surface Guyots – volcanic islands erode flat, sink beneath surface