19.2 Features of the Ocean Floor

1
19.2 Features of the Ocean Floor
2
Areas of Ocean

• 1. Continental Margin
• shallow parts continental crust
• thick sediment

• 2. Deep-Ocean Basin deep parts oceanic crust
  thin sediment

3
Continental Shelf

• Part of a continent that is covered by water
• Gentle slope
• Average depth is 60 m
• Amount exposed changes with changes in sea level

4
(No Transcript)
5
Continental Slope

• Steep slope at edge of continental shelf
• May be cut by deep valleys called submarine
  canyons
• Sediment accumulates at the bottom of the cont.
  slope and is called the continental rise

6
Trenches

• Long, narrow depressions
• Due to one plate subducting (going below) another
  plate
• Earthquakes occur here
• Many volcanoes and volcanic island arcs form here

7
(No Transcript)
8
(No Transcript)
9
Abyssal Plains

• Flattest area on earth
• Cover ½ of deep ocean
• Covered with fine sediment

10

• deep-water sea anemones which appear to be rather
  common on deepwater abyssal plains

11
Mid-Ocean Ridge

• Underwater mountain ranges
• Due to plates pulling away from each other
• A Rift Valley forms in the middle where magma
  comes out
• Have many fracture zones which break the ridge up

12
(No Transcript)
13
(No Transcript)
14
(No Transcript)
15

• Black smoker at a mid-ocean ridge hydrothermal
  vent in the Atlantic.

16
Close up at the mid-ocean ridge
17
Seamounts

• Submerged volcanic mountains
• Called oceanic island if they rise above water

18
Guyot

• Seamounts that have been eroded and are now flat
  on top

19
(No Transcript)