Warm Up 02/07/08

1. Warm Up 02/07/08 • True or False. The ocean floor has less diversity than the continents. • False, it has an equal amount. • What does SONAR stand for? • Sound navigation and ranging • What is bathymetry? • The measurement of ocean depths and the charting of the shape or topography of the ocean floor

2. Ocean Floor Features Chapter 14, Section 2

3. Profile of North Atlantic Ocean

4. Continental Margins • Continental Margin – the zone of transition between a continent and the adjacent ocean basin floor • In the Atlantic Ocean, thick layers of undisturbed sediment cover the continental margin. This region has very little volcanic or earthquake activity • In the Pacific Ocean, oceanic crust is plunging beneath continental crust. This force results in a narrow continental margin that experiences both volcanic activity and earthquakes

5. Passive Continental Margin

6. Continental Shelves, Slopes, and Rises • Continental Shelf – the gently sloping submerged surface extending from the shoreline • Continental shelves contain important mineral deposits, large reservoirs of oil and natural gas, and huge sand and gravel deposits • Continental Slope – the seaward edge of the continental shelf • The continental slope is a relatively narrow feature along the continental shelf • Submarine Canyon – deep, steep-sided valleys cut into the continental slope • Turbidity Currents – occasional movements of dense, sediment-rich water down the continental slope • Turbidity currents are known to be an important factor in sediment transfer in the ocean • Continental Rise – a gradual incline which merges with the steep continental margin, occurs in regions where trenches do not exist

7. Submarine Canyons

8. What land feature does a submarine canyon remind you of? • Mud Slide

9. Ocean Basin Floor • Ocean Basin Floor – area between the continental margin and the mid-ocean ridge • Deep-ocean trenches are long, narrow creases in the ocean floor that form the deepest parts of the ocean • Trenches form at sites of plate convergence where one moving plate descends beneath another and plunges back into the mantle • Abyssal Plains – deep, extremely flat features and are the most level places on Earth • The sediments that make up abyssal plains are carried there by turbidity currents or deposited as a result of suspended sediments settling • Seamounts – the submerged volcanic peaks which dot the ocean floor • Once underwater volcanoes reach the surface, they form islands • After millions of years, the tops are eroded away and the once active islands sink back into the ocean, forming guyots

10. What is a guyot? • An eroded, submerged, flat-topped structure

11. Abyssal Plain

12. Mid-Ocean Ridges • Mid-Ocean Ridge – found near the center of most ocean basins; an interconnected system of underwater mountains that have developed on newly formed ocean crust • Seafloor Spreading – occurs at divergent plate boundaries where two lithospheric plates are moving apart • New ocean floor is formed at mid-ocean ridges as magma rises between the diverging plates and cools • Hydrothermal vents form along mid-ocean ridges and are zones where mineral-rich water escapes through cracks in oceanic crust into the surrounding cooler water

13. Profile of North Atlantic Ocean

14. Assignment • Read Chapter 14, Section 2 (pg. 401-405) • Do Section 14.2 Assessment #1-7 (pg. 405)