1. The World’s Oceans and Their Features Part 1
Clinton Todd
10/19/05
Copyright Clinton Todd. All rights reserved.

2. What Do You Think? Is all land on Earth’s surface flat?
What does the bottom of the ocean look like?
If some parts of the ocean are deep, can we still tell what they look like?

3. The Oceans
About 71% of the Earth’s surface is covered by ocean

4. The Oceans The oceans are divided into four main basins Pacific
Atlantic
Indian
Arctic
The largest ocean and deepest at 3940
Half the size of the Pacific and more narrow
Slightly smaller than the Atlantic but with the same depth
Only about 7% the size of the Pacific and ¼ as deep as the rest

5. The Ocean Floor
The topography of the ocean’s floor is just as varied as that of the land area
Note the relief on the following map…

6. The Ocean Floor

7. Studying the Seafloor
Sonar, developed in the 1920’s transmits sound waves to the ocean floor and plots points on the ocean floor based on the length of time it takes the waves to be reflected back.
Sonar is an acronym for SOund NAvigation and Ranging

8. Studying the Seafloor
Satellites measure sea surface height using the same principle as sonar, except they use radio waves (RADAR), instead of sound
Submersibles small crafts that may be manned or unmanned that use various sensors and instruments to explore the ocean at depth.

9. Ocean Floor Features
There are three major regions of topography that divide the ocean floor
They are the continental margins, the ocean basin floor, and the mid ocean ridge

10. Continental Margins
The area in which continent and ocean floor begin to merge is called the continental margin
The three parts of the continental margin are called the continental shelf, continental slope, and continental rise

11. Continental Margins

12. Continental Margins
The continental shelf is a gently sloping, shallow area of the ocean floor that extends outward from the edge of a continent  
They contain important mineral, oil and natural gas deposits     

13. Continental Margins
The continental slope is a rather steep incline leading down from the seaward edge of the continent shelf
Deep valley called submarine canyons are cut into the slope. These canyons were probably eroded by dense, muddy turbidity currents created by some disturbance, like an earthquake

14. Continental Margins
The continental rise is on the seaward side of the slope and has a much smaller incline
There are no canyons in this region

15. Ocean Basin Floor
The ocean basin floor is between the continental margin and mid-ocean ridge
The region includes deep ocean trenches, abyssal plains, and seamounts and guyots

16. Ocean Basin Floor
Deep-ocean trenches are long and narrow creases that are the deepest parts of the ocean
They form at sites where a moving tectonic plate descends beneath another and goes back into the mantle
The Mariana Trench is the deepest place on Earth at m below sea level!

17. Ocean Basin Floor Abyssal plains are extremely deep and flat
The sediments of the plains come from either turbidity currents that have carried them or from the settling of suspended sediments

18. Ocean Basin Floor Seamounts are submerged volcano peaks
After reaching the water’s surface the volcanoes form islands like the Hawaiian chain
Over millions of years these islands may subside back into the water, where they are then referred to as guyots

19. Mid-Ocean Ridges
Mid-ocean ridges are found near the center of an ocean basin
They are a system of underwater mountains and sites of oceanic crust development
These are places were oceanic plates are diverging and new magma rises from the center

20. Mid-Ocean Ridges

21. Resources:
Ford, Brent A., Project Earth Science:  Geology. Arlington:  National Science Teachers Association, 1996.
Tarbuck, Edward J. and Frederick K. Lutgens. North Carolina Environmental/Earth Science. Prentice Hall. New Jersey
“Mid-Ocean Ridge Spreading.” Windows to the Universe. Jan Oct

22. The World’s Oceans and Their Features
Part 2
QUICK QUIZ

23. Instructions
Navigate through the presentation and answer the questions accordingly on a separate sheet of paper
The numbers for each question are located in the title bar
Note: The picture used for number one may be helpful when answering other questions!

24. 1.) Label the letter in the diagram with the corresponding feature.

25. 2.) New seafloor is formed at mid-ocean ridges as plates
Converge
Diverge
Collide
Sink

26. 3.) The oceans make up what percentage of the Earth’s surface?50 29 93 71

27. 4.) The ______ is a gently sloping, shallow area of the ocean floor that extends outward from the edge of a continent
Guyot
Continental slope
Continental shelf
Abyssal plain

28. 5. )Click the link provided and view the animation
5.)Click the link provided and view the animation. Where does the crust (in yellow) go after being pushed away at the mid-ocean ridge?

29. 6.) Briefly explain different methods by which scientists may map the seafloor.