2. Continental Margin
• That portion of the seafloor adjacent to the
continents; it may include the continental
shelf, continental slope, and continental rise.
4. Continental Slope
• The steep gradient that leads to the deep-
ocean floor and marks the seaward edge of
the continental shelf.
5. Submarine Canyon
• A seaward extension of a valley that was cut
on the continental shelf during a time when
sea level was lower; a canyon carved into the
outer continental shelf, slope, and rise by
turbidity currents.
6. Turbidity Current
• A downslope
movement of dense,
sediment-laden water
created when sand
and mud on the
continental shelf and
slope are dislodged
and thrown into
suspension.
8. Ocean Basin Floor
• Area of the deep-ocean floor between the
continental margin and the oceanic ridge.
9. Abyssal Plains
• Very level area of the deep-ocean floor,
usually lying at the foot of the continental
rise.
10. Seamounts
• An isolated volcanic peak that rises at least
1000 meters above the deep-ocean floor.
11. Mid-Ocean Ridge
• A continuous elevated zone on the floor of all
the major ocean basins and varying in width
from 1000 to 4000 kilometers.
12. Seafloor Spreading
• The process by which plate tectonics produces
new oceanic lithosphere at ocean ridges.
13. Key Concept
• What are the three main regions of
the ocean floor?
–The floor regions are: continental
margins, ocean basin floor, and mid-
ocean ridge.
14. Key Concept
• How do continental margins in the
Atlantic Ocean differ from those in the
Pacific Ocean?
–The Atlantic Ocean has thick layers of
undisturbed sediment cover with very little
volcanic or earthquake activity.
–The Pacific Ocean crust is plunging beneath
continental crust and experiences both
volcanic and earthquake activity.
15. Key Concept
• How are deep-ocean trenches
formed?
–Trenches are formed at sites of plate
convergence where one moving plate
descends beneath another and plunges
back into the mantle.
16. Key Concept
• How are abyssal plains formed?
–The sediments that make up abyssal
plains are carried there by turbidity
currents or deposited as a result of
suspended sediments settling.
17. Key Concept
• What is formed at mid-ocean ridges?
–New ocean floor is formed at mid-
ocean ridges as magma rises between
the diverging plates and cools.
