Sea Floor Notes

The Sea Floor

Geological processes affect dry lands, but also the oceans.

• The geological processes can:
• Determine water depth
• Create new islands
• Shape the shorelines
• Influence the characteristics of the bottom sea floor (it can become rocky, muddy or sandy)

• Habitat: this is the natural environment where an organism resides

The oceans, covering approximately 71% of the Earth, regulate its climate and atmosphere.

• The oceans are categorized into four large basins
• Pacific Ocean
• The largest and deepest ocean
• Atlantic Ocean
• The second largest ocean and has a similar average depth as Indian Ocean
• Indian Ocean
• Has a similar average depth as the Atlantic Ocean
• Arctic Ocean
• The smallest and shallowest ocean

• The Earth also consists of marginal seas that are connected to the main ocean basins
• Some examples are Mediterranean Sea, Caribbean Sea, Coral Sea and Gulf of Mexico
• The four large oceans are interconnected allowing seawater, organisms and other materials to travel from one ocean to the other.

Earth Structure

• Evidences suggest that the Western Hemisphere was once connected to Europe and Africa
• Fossils collected on opposite sides of the Atlantic coast were very similar
• Geological formations and coal deposit were also similar

• In 1912, Alfred Wegener proposed the Continental Drift hypothesis, which stated that all of the continents were once joined together as a single super-continent called Pangaea.
• Also about 180 million years ago, Pangaea had broken into the continents that we now know.
• Description of Pangaea
• Pangaea was surrounded by Panthalassa, the single ocean that covered the whole planet
• Antarctica remained at its current position; all the other continents had different positions
• India and Australia regions were connected to Antarctica and Africa
• Tethys Sea separated most of Africa and Eurasia
• It is the pre-cursor of Mediterranean Sea

• Although the hypothesis was not initially accepted, future evidences supported that continents did drift by plate tectonics.

Plate Tectonics Theory

• Mid-Ocean Ridge

• Sea Floor Development

Continental Margins

• Continental Shelf
• Continental Slope
• The steepest part of the continental margin
• Continental Rise
• This is the base of the continental slope
• Abyssal plain
• This is the deep-sea floor

Hydrothermal Vents

• These are deep sea hot springs
• Black smokers are common in hydrothermal vents
• They consist of solidified sulfide mineral

Sediments

• Two main types of marine sediments:
• Lithogenous sediment
• These are from the physical/chemical breakdown of rocks found primarily on the continent
• Biogenous sediment
• Composed of mostly silica and calcium carbonate

Marine Biology
Sea Floor - SG Learn Online