The Ocean Floor

1. The Ocean Floor

2. Description of Bottom Topography

4. Atlantic Ocean Continental Shelf

5. Typical Oceanic Profile ocean basin continental margin coastalregion oceanic ridge continental shelf Slope Abyssal plain Depth > 4000 m

6. The Continental Margin continental margin ocean basin shelf break coastalregion oceanic ridge continental shelf Slope Abyssal plain continental rise > 4000 m

7. Continental Margin Fig. 2-3a

8. Continental Shelf

9. Coastal Region • Includes: •beaches •estuaries • lagoons • marshes • deltas coastal region Most important region to humans And marine birds and mammals

10. Beaches

11. Typical Salt Marsh

12. Mangrove Swamp

13. Continental Shelf • Definition: shallow part of ocean bottom next to coastline continental margin • SLOPE is less than 0.1° angle continental shelf Slope continental rise

14. Most exposed in Pleistocene

15. Continental Slope and Rise • Slope is 1° to 6° • Rise: less than 1° • Slope & rise can be cut by submarine canyons Slope Continental rise

16. Overlapping fans=cones See Fig. 2-3a

17. San Lucas Submarine Canyon 2 meters

18. Typical Oceanic Profile continental margin ocean basin shelfbreak oceanic ridge continental shelf Slope Abyssal plain continental rise

19. Ocean Basins Are the deep flat areas of the ocean

20. Deep Ocean Basins Fig. 2-3b

21. Seamounts and Guyots- undersea mountains that risemore than 1 km from the seafloor SEAMOUNT Top is rounded May rise above the surface and form an island GUYOT Top flattened by waves

22. 3 Major Oceanic Ridges Mid-Atlantic Ridge Carlsberg Ridge E. Pacific Rise

23. Characteristics of Oceanic Mountain Ridges • Total length: 60,000 km • Present in all oceans • Between 1,000 and 4,000 km wide • mountains are2 - 4 km high • The largest is the Mid Atlantic Ridge half that separatat

24. Mid-Ocean Ridges Fig. 2-3c

25. Mid-Atlantic Ridge Shallow valleys 20 - 30 km wide with high volcanic activity

26. Oceanic Trenches • 31 in the world; • Deep; U or V shaped •These form the deepest places on Earth • Max 130 km wide, 1500 km long

27. Distribution of Trenches

28. Kurile 10,500m Mariana 11,000m Tonga 10,880m 3 _________ trenches

30. Island Arcs are associated with volcanoes

31. shelf Ridge shelf slope slope hills plains Atlantic Ocean island arc plain seamounts slope ridge Pacific Ocean trench

32. At a hydrothermal vent, sea water that has sunken into cracks in the ocean crust and been heated (sometimes to over 180 degrees!) by the interior of the earth escapes through crust cracks back into the ocean. HYDROTHERMAL VENTS or BLACK SMOKERS • http://www.pmel.noaa.gov/vents/nemo/explorer/multimedia.html

33. The superheated water beneath the oceanic crust often dissolves minerals from nearby rocks. • The precipitating minerals often give vent fluids different colored “smoky” appearances.

34. As hot vent fluids meet cold ocean water, minerals precipitate (fall) out of vent fluids. • The precipitating minerals form “chimneys” and other formations on the sea floor.

35. Hydrothermal Vent Sites