1. The Ocean Floor

2. Description of
Bottom Topography

4. Atlantic Ocean
Continental Shelf

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

6. The Continental Margin
ocean basin
shelf break
coastal region
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 less than 0.1° angle
• 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°
Rise is about 20 km in Atlantic along passive margins
Can be absent altogether in active margins with trenches.
• 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
shelf break
oceanic
ridge
continental shelf
Slope
Abyssal plain
continental
rise

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

20. Deep Ocean Basins
Fig. 2-3b

21. May rise above the surface
Seamounts and Guyots- undersea
mountains that rise more 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. The largest is the Mid Atlantic Ridge half that separatat
Characteristics of Oceanic Mountain
Ridges
• Total length: 60,000 km
• Present in all oceans
• Between 1,000 and 4,000 km wide
• mountains are 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 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
10,500 m
Mariana
11,000 m
Tonga
10,880 m
3 _________ trenches

30. Island Arcs are associated with volcanoes

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

32. HYDROTHERMAL VENTS or BLACK SMOKERS
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.

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