1. The Sea Floor CH 2 pg 19

2. Geosphere

3. Geological processes influenced terrestrial and marine environments
Earth is broken into layers..
Crust
Mantle
Core (inner/outer)

4. Geological Layers of Earth
Crust - 1% Earth’s mass thinnest layer
Continental
Granite, less dense, floats on top oceanic
Oceanic
Basalt, dense, thinner than continental

5. Lithosphere is part of the upper mantle

6. Mantle - layers beneath the crust
Lithosphere (broken into plates; tectonic)
Asthenosphere (plates float on top)
“Silly putty”
Heated and becomes less dense so material rises then as it cools material sinks creating circulating currents called convection currents
Causes plates to move

8. Geological Layers of Earth
Core - innermost layer
Outer core
Dense liquid
Moves counter clockwise thought to create magnetic field
Inner core
Solid due to pressure
Iron and Nickel

10. Oceans
71% of Planet
Regulate climate and atmosphere

11. Geography of the Ocean Basin
2/3 of the earth’s land area in the Northern Hemisphere
The Southern Hemisphere
80% of the ocean

12. Five Large Basins Pacific Ocean Atlantic Ocean Indian Ocean
deepest (approx ft) and the largest
narrowing
Atlantic Ocean
Slowly getting bigger
Indian Ocean
Arctic Ocean
Southern Ocean
Difference between ocean and sea?

14. The Origin and Structure of the Ocean Basins
(1912) Continental Drift Theory
All the continents had once been joined in a single “supercontinent” called Pangea
Approx 180 m.y.a.
(1950s and 1960s) Plate tectonics
Plates did drift lead to the discovery of the Mid-Ocean Ridge

15. Evidence Pieces of a puzzle Matching sequences of rock & mountains
Distribution of organisms
Magnetic fields
Igneous rock
Magnetite and iron

16. The Mid-Ocean Ridge System of volcanic mounts that encircles the globe
Largest geological feature on earth
Submarine mountains can break the surface of the water to form islands (ex. Iceland)
Eastern – Pacific Ridge (Subduction)

17. Subduction vs Divergent

18. Creation of the Sea Floor
Pieces of oceanic crust separate mid-ocean ridges by creating cracks called rifts.
Rifts release the pressure on the mantle
Reduced pressure allows hot mantle material to rise up through the rift.

19. The magma pushes up around the rift
It cools as it enters the surrounding water
Creating a ridge
Atlantic Ocean getting larger (Divergent)

20. Creating New Seafloor
Repeating process makes the seafloor move away from the mid-ocean ridge
Mid-ocean ridge form the edges of continents
As the plates move the continent is carried with it (2.5 ~ 7cm/year)
Seafloor younger closest to the ridge

21. Aleutian Islands pg 28 Trenches curve due to Earth’s spherical shape
Volcanic islands follow trenches
Island Arcs

22. Hot Spots pg 36
Hawaiian Islands (plate movement) vs Aleutian Islands (subduction)
Hawaiian Islands are formed as a result of the movement of plate over a “hot spot”
Magma oozes from the thinner oceanic crust
Cools and creates a seamount
Eventually breaks the surface
Southern islands are younger

24. Continental Volcanoes pg23
Collision between ocean and continental plates result in volcanoes
Continent vs Continent
Himilayas & Great Smokey Mountains

25. Transform Boundaries Shear boundary Plates that slide past each other
Friction prevents the plates from sliding smoothly
They lock up and stress builds up until the plates break free
Cause an earthquake
San Andres Fault (pg 29)

26. The Ocean Floor Sea floor is dominated by plate tectonics
Sea floor is divided into two main regions;
Continental margin
Deep-sea floor

28. Continental Margins
Region between the continental crust and oceanic crust
Continental Shelf
Continental Slope
Continental Rise

29. Continental Shelf Shallow makes up 8% of the ocean’s surface area
ft deep
Rich in life ends at the shelf break
Continental crust covered in sea water

31. Continental Slope Exact edge of the continent
Starts at the shelf break
Descends to the deep-sea

32. Continental Rise
Sediment forms at the base of the continental slope

33. Deep-Ocean Basins Mariana Trench 10,000 – 16,500 ft deep abyssal plain
West Pacific
Depth of 36,163ft (7 miles)

34. Hydrothermal Vents Fractures in crust water seeps down
Heated water pushes its way up
Creating a hydrothermal vent
Temp ranging from (50 – 550o)
The water contains minerals and sulfides

36. As the water cools the minerals solidify and deposit themselves around the vents creating chimneys, commonly called black smokers.
Tallest chimney so far rises 200 ft above sea floor