Submarine Surfaces

• Oceans and Features %

  • The oceans account for 70% of Earth’s surface
  • Deep ocean basins account for 42-47% of the ocean
  • And mid ocean ridges at 31%
• Tectonic perspective of Deep Oceans and Ridges

  • Deep ocean basins- Average depth of 4 km, flat sediment plains as well a seamounts
  • Mid Ocean Ridges- Depth of 2.6-2 km, the longest mountain range of 65,000 km
• Ocean Floor Mapping

  o   Only 15% is measured by sonar

  o   Different methods of floor mapping – echo sounder (side or multi beam sonar), seismic reflection profiler, remotely operate vehicles, satellite altimetry
• Deep Sea Trenches

  o   Can evolve structurally to be starved or filled with sediments

  o   Usually form adjacent to convergent margins
• Mid Ocean Ridges

  o   Well preserved features, formed through volcanics, tectonics, hydrothermal and sedimentary processes
• Abyssal Hills and Plains

  o   Abyssal plains result from the blanketing of an originally uneven surface of oceanic crust by fine-grained sediments

  o   Due to extensional faulting, most abundant geomorphic structures on Earth

  o   The slower the spreading rate, the larger their dimensions
• Seamounts

  o   Underwater mountains or volcanic peaks, that do not reach the surface of the water
• Submarine Landslides

  • Evidence of submarine landslides are preserved in in deep water valleys where sediments fall and lay undisturbed
• Continental Margins

  o   The outer edge of continental crust, which shelves, slopes and rises

  o   It is off the continental shelf that submarine canyons occur

  o   Submarine canyons are steep sided valleys cut into the seabed of the continental shelf with nearly vertical walls

  o   Cover around 11% of the ocean floor

  o   Major canyon off the shelf of Perth

  o   Upper canyons are meandering and V shaped

  o   Middle canyons are smoother and U shaped

  o   Lower canyons are lower in relief

  o   Also, evidence of glacial erosional features such as moraines and eskers