Chapter 3

Question 1

1) Satellites are used to map the ocean floor because ________.
A) they are affected by surface weather
B) they can’t cover areas where ships have not produced surveys
C) they can only “see” small areas of the seafloor at one time
D) the shape of the ocean surface reflects large features on the seafloor
E) they are inexpensive to build and launch

Answer 1

the shape of the ocean surface reflects large features on the seafloor

Question 2

2) Relatively few abyssal plains are located in the Pacific Ocean due to ________.
A) its smaller size compared to other ocean basins
B) the presence of convergent active margins
C) the absence of convergent active margins
D) the presence of seamounts
E) its location in northern and southern hemispheres

Answer 2

the presence of convergent active margins

Question 3

3) Segments of the oceanic ridge system that are gentler and less rugged in slope due to faster rates of seafloor spreading are called
\_\_\_\_\_\_\_\_.
A) deep-sea trenches
B) fracture zones
C) oceanic rises
D) convergent plate boundaries
E) transform faults

Answer 3

oceanic rises

Question 4

4) Passive margins are usually produced over geologic time by which of the following?
A) Continental rifting and continued sea floor spreading
B) Hot spot volcanism forming a chain of islands and seamounts
C) Subduction of oceanic crust and submarine volcanic activity
D) The closing of an ancient sea to form a salt rich lake
E) Transform faulting along a continental margin or a mid-ocean ridge

Answer 4

Continental rifting and continued sea floor spreading

Question 5

5) Which of the following best describes turbidity currents?
A) Metal-rich deposits that form on the flanks of submarine volcanoes
B) Muddy water brought to the ocean by rivers and streams to form a delta
C) Rift-valley sediments found within the depression at mid-ocean ridges
D) Turbid water that kills coral and other photosynthesizing creatures by blocking light
E) Underwater avalanches of muddy water mixed with rocks and other debris

Answer 5

Underwater avalanches of muddy water mixed with rocks and other debris

Question 6

6) Which of the following is the predominant process that forms the thick blanket of sediment on abyssal plains the deep-ocean floor?
A) Black smokers
B) Melting icebergs
C) Precipitation
D) Suspension settling
E) Undersea streams

Answer 6

Suspension settling

Question 7

7) Oceanographers who want to know about ocean structure beneath the sea floor use which of the following techniques?
A) Magnetometer
B) Multibeam Sonar
C) Seismic Reflection
D) Side-scan Sonar
E) Sounding

Answer 7

?????Seismic Reflection

Question 8

8) The Big Island of Hawaii is an example of a volcanic island associated with volcanic activity at a \_\_\_\_\_\_\_\_.
A) hotspot
B) island arc
C) mid-ocean ridge
D) transform fault
E) deep sea trench

Answer 8

?????hotspot

Question 9

Draw the SEAFLOOR DIAGRAM:

Answer 9

See notebook notes for answer

Question 10

Students sometimes ask… What effect does all this volcanic activity along the mid-ocean ridge have at the ocean’s surface.

Answer 10

• Underwater Volcanic Reaction= creates megaplume of war
• mineral-rich water that is lower in density than the surrounding seawater and thus rises to the surface.
• The heat released into the ocean at mid-ocean ridges is probably not very significant, mostly because that ocean is so good at absorbing and redistributing heat.

Question 11

Students sometimes ask… If black smokers are so hot, why isn’t there steam coming out of them instead of hot water?

Answer 11

• four times the boiling point of water at the ocean’s surface and hot enough to melt lead.
• location of black smokers the pressure is much higher than at the surface
• water from hydrothermal vents remains in the liquid state instead of turning into water vapor.