The Sea Floor

The Sea Floor

1. Continental Margin= shelf and slope and rise

   • extends from shoreline to shelf break
     • depth= 135 m

2. submarine canyons

   • undersea landslides
   • deposition of sed. to form submarine fans
   • due to turbidity currents

3. carbonate materials and reefs

   • depends on climate
     • needs warm water
     • needs clean H2O= lots of sunlight
   • fringing reefs (along shore)
   • barrier reefs (separated from shore by lagoon)
   • atoll (circular reef around submerged volcanic island)

4. abyssal plains

   • landforms in deep ocean
     • basalt underlies ocean floor BUT in abyssal plains, surface covered with sediment
       • turbidity deposits
       • pelagic deposits
       • wind blown and ice transported materials
       • cosmic (meteoritic debris)
       • products of submarine weathering
         • basalt weathering= clay deposits
       • calcareous ooze
       • siliceous ooze
         • shells of siliceous plants and animals
         • lithifies to form chert

5. ocean ridges

   • very extensive
   • marks divergent plate boundaries
   • sea floor spreading
     • continuously forming new ocean crust
       • fissure eruptions of basalt magma
       • ocean crust
         • pillow basalts
           • erupted along ocean ridges from fissures
         • dykes of gabbro
           • feeders to pillow basalt
         • deep-sea sediment
           • mostly pelagic
           • on top of pillow basalt
         • Moho makes up bottom of ocean crust
           • boundary btw. earth's crust and mantle

6. ocean trenches

   • deepest part of ocean

7. fracture zones

8. seamounts and oceanic islands

Images and files in the map