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Marine Biology / Chapter 2 – The Sea Floor

Marine Biology / Chapter 2 – The Sea Floor. The Water Planet The Geography of the Ocean Basins. Traditionally classified into four large basins: The Pacific – deepest and largest The Atlantic Ocean The Indian Ocean The Arctic Ocean.

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Marine Biology / Chapter 2 – The Sea Floor

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  1. Marine Biology / Chapter 2 – The Sea Floor The Water Planet The Geography of the Ocean Basins

  2. Traditionally classified into four large basins: • The Pacific – deepest and largest • The Atlantic Ocean • The Indian Ocean • The Arctic Ocean

  3. Connected or marginal to main basins – shallow seas ie Mediterranean Sea, Gulf of Mexico, South China Sea.

  4. The Structure of the Earth • The external structure • The internal structure

  5. The Structure of the Earth • Earth and solar system thought to have formed about 4.5 bya • formed from debris left over from the “Big Bang” about 13.7 bya • early forms entire planet probably molten • allowed materials to settle in the planet according to their density

  6. Density is the mass of a substance per unit volume • Substances of low density will float on substances o higher density. • Density = mass/volume

  7. The Internal Structure • reflects planets early beginnings • materials sank according to density – formed concentric rings • innermost layer – core • pressure more than 1 million greater than surface • temp. estimated to be more than 7200o F

  8. Mantle – layer outside the core • very hot; near rock melting point • state of plastic – moves or swirls very slowly • Crust is outer most layer • Composition and character differ between oceanic and continental

  9. oceanic crust is denser and consist of basalt • continental crust less dense and consist mainly of granite • Both are less dense than underlying mantle.

  10. oceanic and Continental crust also differ in age. • Oldest oceanic rocks are less than 200 million years old. • Continental rocks can be as much as 3.8 billion years old.

  11. Origin and structure of the ocean basins • As early as 1620 – noted that coastlines of continents on opposite sides of the Atlantic fit together like pieces of a puzzle • Cold deposits, geological formations, match up on opposite sides of the Atlantic • Fossils on opposing coast also match

  12. Alfred Wegner - 1912 – proposed first detailed hypothesis of continental drift • Suggested single super continent he named Pangaea • Proposed Pangaea began breaking the about 180 million years ago

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