1. The Sea Floor

2. A: Right! The Southern Hemisphere contains nearly 80% water by volume.
Brain Warmers:
Q: Of the Northern and Southern Hemisphere, which one contains the most water??
A: Right! The Southern Hemisphere contains nearly 80% water by volume.
Q: Which ocean is the largest? The deepest?
a. Arctic b. Pacific c. Atlantic d. Indian
A: Pacific
A: Pacific again!

3. Figure 2.02

5. How did it all get this way?
Big bang leftovers!
Density played a major role.
How’s that work??
Density = mass/volume
Lighter stuff stays on the top!

6. Figure 2.03

7. Ocean Floor Facts
Ocean crust is composed of basalt. Basalt is common to the sea floor also.
Much of the crust which forms land masses is composed of granite.
Much of the ocean floor and crust differs in age too! (200 myo compared to 3.8 byo!!)
Why??

8. About what percent of the Earth’s surface is covered by ocean?
50%
71%
85%
25%

9. Which is true? The Pacific ocean is deepest and smallest
The Arctic ocean is shallowest and smallest
The Atlantic ocean is deepest and largest
The Indian ocean is shallowest and largest

10. Ocean Floor Structure
Sir Francis Bacon (1620) considered continents puzzle pieces.
Geological features (coal deposits) matched on opposite coasts.

11. Figure 2.04

12. Ocean Floor Structure
Sir Francis Bacon (1620) considered contents puzzle pieces.
Geological features (coal deposits) matched on opposite coasts.
Alfred Wegner (1912) hypothesized continental drift.

13. 180 mya
Pangea Bound…
Continents may have been one piece which later broke apart, moved, and formed present day conditions.
How??
Plate tectonics ocean floor movement.
Consists of faults (cracks) which form the mid ocean ridges (mountains).
150 mya
95 mya
45 mya
15 mya

14. Current Mid-ocean ridges & trenches
Figure 2.05
Current Mid-ocean ridges & trenches

16. These locations are a significant source of geological activity!
Figure 2.06
These locations are a significant source of geological activity!

18. Figure 2.07

20. Magnetic anomalies occur here too!
Figure 2.08
Sea floor spreading occurs at
mid-ocean ridges.
Magnetic anomalies occur here too!
“Okay, Miss Collins. You’re using
big words again!!”

21. Magnetic anemone!! But seriously….

22. Sea-floor spreading
where the ocean floor
moves away from
the mid-ocean ridge
records the magnetic
fields of the earth.

23. Locations and direction of seafloor spreading.
Figure 2.10
Locations and direction of seafloor spreading.

24. Crust and mantle come together to form the lithosphere.
Figure 2.11
Crust and mantle come together to form the lithosphere.
Subduction, and resulting subduction zones, are where ocean floor
plates flow beneath the mantle of the crust and are places of tectonic activity.

25. Trenches and island arcs can be formed when two sections of ocean
Figure 2.12
Trenches and island arcs can be formed when two sections of ocean
plates come together.

26. Some areas can be quite active!!
Figure 2.13
Mt. Veniaminof, Alaska
Some areas can be quite active!!

27. sideways then there is a new formation called a shear-boundary.
Figure 2.14
When plates move
sideways then there is a new formation called a
shear-boundary.
San Andreas Fault, CA

28. Figure 2.15
Swirling vs. Pulling
Convection suggests that continents move on a “soup” of rock,
whereas slab pulling indicates that as rock cools, it sinks beneath
the surface and “pulls” lithosphere into the depths (This is the
currently accepted explanation.)

29. Magnetic anomalies are bands of rock that run parallel to the mid-ocean ridge system. What do they provide evidence for?
Bacteria lived in the ocean floor millions of years ago
Volcanoes form at ocean ridges.
The sea floor was formed in layers
Granite is denser than basalt

30. Continental plates are believed to move because of which of these causes?
New volcanic rock pushes them away from spreading centers.
Cooling lithosphere becomes dense, sinks, and pulls a plate with it.
Plates crack along fault lines.
The mantle is fluid and carries plates along with it

31. Ocean sediments often preserve organisms which help
Figure 2.17
Ocean sediments often preserve organisms which help
scientists age the ocean floor.
Lithogenous sediment contains minerals, while biogenous
sediment contains fossil remains.

32. Figure 2.19

33. Figure 2.20

34. Figure 2.21

35. Figure 2.22

36. Figure 2.23

37. Figure 2.24

38. The biologically richest area of the seafloor is
The continental shelf.
The continental slope.
The plain.
Deep-sea vents.
The abyssal plain

39. Red clay is an example of biogenous sediment.
True
False

40. A swimmer sees a shark. Some sharks are dangerous
A swimmer sees a shark. Some sharks are dangerous. The swimmer swims away from the shark based on this information.
Tested a hypothesis
Used inductive reasoning
Formed a theory
Used deductive reasoning

41. Which of the following is a valid scientific hypothesis?
Dogs are superior pets.
It is immoral to keep whales in captivity.
Dolphins use brainwaves to communicate.
One-spot foxface rabbitfish prefer green algae to red algae.

42. Figure 2.25

44. Figure 2.26

45. Figure 2.27

46. Text Art 2.01

47. Text Art 2.02

48. http://www. youtube. com/watch. v=zRfaZqeehc0 http://www. youtube