Multiple Choice

 

  1. Which one of the following is NOT part of the continental margin?

a. continental shelf

b. continental slope

            c. continental rise

            d. continental trench

 

  2. It is thought that submarine canyons on the continental slope have been generated by __________

a. streams when sea-level was much lower than it is today                     

b. streams when sea-level was much higher than it is today

c. a submarine glaciation

d. turbidity currents

 

  3.  Which one of the following would you NOT associate with turbidity currents?

a. deposits of graded beds                                 

b. density current

c. excavation of submarine canyons                               

d. formation of seamounts

 

  4.  Which one of the following would most likely be covered with thick turbidite layers?

            a. axial rift zone of an active mid-ocean spreading center

            b. upper part of a steep, narrow, submarine canyon

            c. deep-sea fan at the base of a continental slope

            d. ocean floor around a conical-shaped seamount

 

  5.  Which of the following is NOT true of deep ocean trenches?

            a. they are long and narrow depressions

            b. they are sites where plates plunge back into the mantle

            c. they are geologically very stable

            d. they may act as sediment traps

 

  6.  The BEST definition of the outer edge of the continental shelf is that point where __________.

a. the gradient becomes very gentle                                           

b. the water depth reaches 100 fathoms

c. it meets an oceanic ridge                                                                   

d. a rapid steepening of the gradient occurs

 

  7.  Seamounts ____________.

            a. are a special type of oceanic trench

            b. are volcanoes that form on the ocean floor

            c. form only in the Pacific Ocean basin

            d. are submarine canyons found near Australia

 

  8.  Submarine canyons found on the continental slope and are believed to have been created ____________.

            a. by rivers during the ice age                                                    

            b. by faulting

            c. because of a plate plunging into the mantle     

            d. none of these

 

  9.  Which of the following is associated with ocean ridges?

a. rift zones                                                                                                                  

b. mountainous topography

c. volcanic structures                                                                            

d. all of these

 

10. How do calcareous oozes form?

            a. the particles are precipitated in warm, surface waters and sink to the bottom

            b. the particles are precipitated by bottom-dwelling organisms

            c. the particles are precipitated in the water column below the depth of sunlight penetration and then sink to the bottom

d. the particles settle out from calcite-rich turbidity currents at depths greater than 15,000 feet

 

11. Sediments derived primarily from the products of weathering on the continents are called __________.

a. terrigenous sediment                                                                         

b. biogenous sediment

c. hydrogenous sediment                                                                       

d. both terrigenous and biogenous sediment

 

12.  Manganese nodules are an example of __________.

a. terrigenous sediment                                                                     

b. biogenous sediment

c. hydrogenous sediment                                                                       

d. both terrigenous and biogenous sediment

 

13. Minerals that crystallize directly from seawater are examples of __________.

a.  terrigenous sediment                                                            

b. biogenous sediment

c. hydrogenous sediment                                                           

d. both terrigenous and biogenous sediment

 

14. The gently sloping submerged surface extending from the shoreline toward the deep ocean is termed the ____________.

a. continental shelf                                                                                            

            b. continental slope

            c. continental rise                                                                                             

            d. submarine canyon

 

15.  The crests of mid-oceanic ridges __________.

a. are heavily mantled with sediment                                          

b. lie at depths exceeding 6 kilometers

c. contain active rift zones                                                                     

d. are geologically old features

 

16.  ____________ develop where oceanic lithosphere bends downward and sinks into the mantle.

            a. Submarine canyons               

b. Abyssal seamounts

c. Deep ocean trenches                                                                        

d. Rift valleys on mid-ocean ridges

 

17.  An echo sounder operates by measuring the time required for a ____________.

            a. light beam to travel from a satellite at a known altitude to the sea bottom and back

            b. radar beam to travel from a harbor patrol boat to a fuzz-buster on a speeding yacht

            c. radar beam to travel from a ship to the seafloor and back

d. sound pulse travels from a ship to the seafloor and back

 

18.  The oceans cover approximately __________ percent of Earth's surface.

a. 40                                                    

b. 50                                                    

c. 60                                        

d. 70

 

19.  The _______ Ocean is largest.

a. Atlantic                                            

b. Pacific                                             

c. Indian                                  

d. Arctic

 

20.  Which ocean has the greatest average depth?

a. Atlantic                                            

b. Pacific                                             

c. Indian                                  

d. Arctic

 

21.  Which one of the following salts is most abundant in seawater?

a. potassium bromide                                        

b. magnesium chloride

c. sodium bicarbonate                                                                           

d. sodium chloride

 

22.  Concerning the distribution of land and water, which of the following statements is true?

a. the percentage of land and water is about the same in both the Northern and Southern Hemispheres

b. the Southern Hemisphere has much more water surface than the Northern Hemisphere

c. the Northern Hemisphere has much more water surface than the Southern Hemisphere

d. none of the above are true

 

23.  The continental rise is located ____________.

            a. at the top of a mid-ocean ridge                

            b. at the top of the continental slope

            c. between an abyssal plain and continental slope

d. at the seaward edge of a deep ocean trench

 

24.  Which one of the following concerning mid-ocean ridges is false?

            a. are sites for submarine eruptions of basaltic lava

            b. are where young lithosphere is added to the edges of spreading, oceanic plates

            c. terrigenous sediment coverings are very thin or absent

d. sediments include thick siliceous ooze deposits and sandy turbidite beds

 

25. The __________ Ocean has more extensive abyssal plains than the Pacific Ocean because it has fewer trenches to trap sediments moving down the continental slope.

a. Indian                                  

b. Atlantic                                            

c. Arctic                                              

d. none of these

 

26. "Black smokers" are associated with ____________.

            a. oceanic ridges

            b. mineral-rich waters

            c. hot water

            d. all of these

 

27. The __________ marks the transition between the warm surface layer and the deep zone of cold water in the oceans.

a. halocline

b. pycnocline                            

c. salinocline                            

d. thermocline

 

Answers:

  1. d

  2. d

  3. d

  4. c

  5. c

  6. d

  7. b

  8. d

  9. d

10. a

11. a

12. c

13. c

14. a

15. c

16. c

17. d

18. d

19. b

20. b

21. d

22. b

23. c

24. d

25. b

26. d

27. d