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

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

6. The Structure of the Earth
The external structure
The internal structure

7. 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

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

9. 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

10. 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

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

13. 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.

14. 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

16. 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