Earth science 14.2

Earth science 14.2

• 1.
  Ocean Floor Features14.2
• 2.
  Continental Margin • Thatportion of the seafloor adjacent to the continents; it may include the continental shelf, continental slope, and continental rise.
• 3.
  Continental Shelf • Thegently sloping surface at the base of the continental slope.
• 4.
  Continental Slope • Thesteep gradient that leads to the deep- ocean floor and marks the seaward edge of the continental shelf.
• 5.
  Submarine Canyon • Aseaward 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 • Adownslope movement of dense, sediment-laden water created when sand and mud on the continental shelf and slope are dislodged and thrown into suspension.
• 7.
  Continental Rise • Thegently sloping surface at the base of the continental slope.
• 8.
  Ocean Basin Floor •Area of the deep-ocean floor between the continental margin and the oceanic ridge.
• 9.
  Abyssal Plains • Verylevel area of the deep-ocean floor, usually lying at the foot of the continental rise.
• 10.
  Seamounts • An isolatedvolcanic peak that rises at least 1000 meters above the deep-ocean floor.
• 11.
  Mid-Ocean Ridge • Acontinuous elevated zone on the floor of all the major ocean basins and varying in width from 1000 to 4000 kilometers.
• 12.
  Seafloor Spreading • Theprocess by which plate tectonics produces new oceanic lithosphere at ocean ridges.
• 13.
  Key Concept • Whatare the three main regions of the ocean floor? –The floor regions are: continental margins, ocean basin floor, and mid- ocean ridge.
• 14.
  Key Concept • Howdo 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 • Howare 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 • Howare 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 • Whatis formed at mid-ocean ridges? –New ocean floor is formed at mid- ocean ridges as magma rises between the diverging plates and cools.