1. The Ocean Floor subsurface topography
Ch. 13~2
(before the 1900’s scientists thought the ocean floor was completely flat)

2. Sonar (sound navigation and ranging) invented during WWI
* To find depth: use the formula:
Depth = V x t
(remember that you only want half the time)
units = meters (m)
…where velocity of sound in ocean water is about 1,500 m/s

3. Water Pressure Water Pressure demo (with 2L bottle) Water pressure
increases with depth 
Part of the Titanic

4. Continental Margin

5. >>submarine canyons caused by erosion and underwater landslides

6. ABYSSAL PLAIN
Flat area of ocean floor

7. Mid-Ocean Ridge Divergent boundary Sea-floor spreading
New sea floor formed

8. What do you notice about the shape of the mid-Atlantic ridge?

9. Seamount Underwater volcanoes
If they reach the surface they form islands, like Iceland.
FYI—called guyots if flat-topped (due to erosion)

10. Iceland

11. TRENCH At convergent boundary
Ex: the Mariana Trench is the deepest known place on earth
11034 meters
(36200 ft) deep

12. The Ocean Floor Continental slope Volcanic island Continental slope
Continental shelf
Continental shelf
Seamount
Abyssal plain
Mid-ocean ridge
Trench

13. 3D model of the Ocean floor (as a group)
After you build the ocean floor, use toothpicks and sticky labels to identify the following ocean features:
1. continental shelf
2. continental slope
3. MID-ocean ridge
4. abyssal plain
5. seamount
6. trench—should not be right next to mid-ocean ridge (should be at subduction zone)

14. Omit section 3, except:

15. Questions
If you were able to walk along the ocean bottom from a beach, which feature would you reach after the continental shelf?
….continental slope

16. The area under water that is closest to the shoreline is the
A. continental shelf
B. continental slope
C. mid-ocean ridge
D. benthic

17. The __________ is the broad, FLAT part of the deep-ocean basin
A. abyssal plain
B. continental shelf
C. mid-ocean ridge
D. benthic

18. At which point in the diagram above would hot magma most likely rise through the ocean floor to eventually form a volcanic island?
Point B

19. Which is most like a mountain RANGE?
A. A seamount
B. A guyot
C. The abyssal plain
D. The mid-ocean ridge
Note: A seamount is a single underwater mountain.