Name_______________________________ Class __________________ Date __________________
Skills Worksheet
Directed Reading
Section: Features of the Ocean Floor
_____ 1. How many major areas does the ocean floor have?
a. one
b. two
c. three
d. four
_____ 2. The shallow ocean floor between the shoreline and the deep-ocean
basin is called the
a. continental margin.
b. shallow-ocean basin.
c. continental crust.
d. oceanic crust.
_____ 3. Continental margins are made up of continental crust
a. and a thin sediment layer.
b. and a thick wedge of sediment.
c. without a sedimentary layer.
d. or a sedimentary layer.
_____ 4. The part of the ocean floor under deep water beyond the continental
margin is called the
a. continental margin.
b. deep-ocean basin.
c. continental crust.
d. oceanic crust.
_____ 5. The deep-ocean basin is made up of oceanic crust
a. and a thin sediment layer.
b. and a thick wedge of sediment.
c. without a sedimentary layer.
d. or a sedimentary layer.
CONTINENTAL MARGINS
_____ 6. The line that divides the continental crust from the oceanic crust is
a. distinct.
b. on the surface.
c. under thick sediments.
d. at the shoreline.
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The Ocean Basins
Name_______________________________ Class __________________ Date __________________
Directed Reading continued
_____ 7. The part of the continent covered by water is called the
a. shoreline.
b. continental margin.
c. continental shelf.
d. deep-ocean basin.
_____ 8. The continental shelf slopes gently from the shoreline, and drops about
0.12 m every
a. 10 m.
b. 100 m.
c. 1,000 m.
d. 10,000 m.
_____ 9. The average depth of the water covering a continental shelf is about
a. 6 m.
b. 60 m.
c. 160 m.
d. 600 m.
_____ 10. The continental shelf is part of the
a. continental margin.
b. deep-ocean basin.
c. ocean surface.
d. oceanic crust.
_____ 11. During glacial periods,
a. sea level rises.
b. sea level falls.
c. sea level is unchanged.
d. continental shelves rise.
_____ 12. More continental shelf is exposed to weathering and erosion
a. when ice sheets melt and sea level rises.
b. during glacial periods when ice sheets hold large amounts of water.
c. at the beginning of glacial periods when ice begins to freeze.
d. at the end of glacial periods when ice begins to melt.
_____ 13. The steep slope at the seaward edge of a continental shelf is called the
a. continental rise.
b. continental slope.
c. oceanic slope.
d. oceanic rise.
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The Ocean Basins
Name_______________________________ Class __________________ Date __________________
Directed Reading continued
14. Where is the boundary between the continental crust and the oceanic crust?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
15. About how steeply does the ocean depth increase along the continental slope?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
16. Deep V-shaped valleys in the continental shelf and continental slope are called
______________________.
17. What is one place submarine canyons are often found?
_______________________________________________________________
_______________________________________________________________
18. How can turbidity currents help form submarine canyons?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
19. How do turbidity currents form?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
20. The wedge of sediment at the base of the continental slope is called a(n)
______________________.
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The Ocean Basins
Name_______________________________ Class __________________ Date __________________
Directed Reading continued
DEEP-OCEAN BASINS
21. What are four features of deep-ocean basins?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
22. How do the mountains and the plains in deep-ocean basins compare to those
on the surface of the continents?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
23. What is the name of the deepest place in Earth’s crust?
_______________________________________________________________
24. Where is the deepest place in Earth’s crust located?
_______________________________________________________________
25. About how deep is the deepest place in Earth’s crust?
_______________________________________________________________
26. In deep-ocean basins, what is a trench?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
27. How do trenches form in deep-ocean basins?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
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The Ocean Basins
Name_______________________________ Class __________________ Date __________________
Directed Reading continued
28. List three things that occur or form near trenches.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
29. In deep-ocean basins, what are abyssal plains?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
30. About half the deep-ocean basins are covered by
______________________________________________________________ .
31. The flattest regions on Earth are ____________________________________.
32. Layers of fine ______________________ cover the abyssal plains.
33. What are two sources of sediments covering the abyssal plains?
_______________________________________________________________
_______________________________________________________________
34. How does the age of the oceanic crust affect the thickness of sediments on the
abyssal plains?
_______________________________________________________________
_______________________________________________________________
35. How does distance from the continental margin to the abyssal plains affect the
thickness of sediments?
_______________________________________________________________
_______________________________________________________________
36. Compare the sediment cover on abyssal plains that are bordered by trenches
with the sediment cover on abyssal plains not bordered by trenches.
_______________________________________________________________
_______________________________________________________________
37. The most prominent features of ocean basins are _______________________.
38. Mid-ocean ridges form underwater __________________________________.
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The Ocean Basins
Name_______________________________ Class __________________ Date __________________
Directed Reading continued
39. What is one place where a mid-ocean ridge rises above sea level?
_______________________________________________________________
40. Where do mid-ocean ridges form?
_______________________________________________________________
41. What runs along the center of a mid-ocean ridge?
_______________________________________________________________
42. How does magma reach the sea floor?
_______________________________________________________________
43. What is formed when magma reaches the sea floor?
_______________________________________________________________
44. What happens to new lithosphere as it cools?
_______________________________________________________________
45. Blocks of crust bounded by faults, called ______________________, form
parallel to ridges as lithosphere cools and contracts.
46. What happens as ridges adjust to changes in the direction of plate motions?
_______________________________________________________________
_______________________________________________________________
47. Faults create rough areas called ______________________, which run
perpendicularly across mid-ocean ridges.
48. Where do seamounts form?
_______________________________________________________________
_______________________________________________________________
In the space provided, write the letter of the definition that best matches the term
or phrase.
_____ 49. guyot
_____ 50. hot spot
_____ 51. seamount
_____ 52. atoll
_____ 53. oceanic island
a. an area of increased volcanic activity
b. submerged seamount with a flat top
c. a seamount that rises above the ocean surface
d. an oceanic island formed from coral reefs that
surround a sinking and eroding seamount
e. submerged volcanic mountain taller than 1 km
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The Ocean Basins