1. Ch. 6
Plate Tectonics

2. 6-1 Continental Drift
Continental Drift theory that the continents were once a single land mass that broke apart
Pangaea supercontinent

4. Evidence of Continental Drift
South America & Africa look like they fit together
Fossils of mesosaurus found in S. America & Africa

5. Evidence of Continental Drift cont.
Mountains on different continents match
U.S. & Canada match w/ Greenland & Europe
Sizes of diamonds in Brazil & W. Africa match

7. 2 types of crust Continental Oceanic 6-2 Seafloor Spreading Less dense
More dense

8. Mid-ocean ridge underwater mt. chain in the oceans
6-2 cont.
Mid-ocean ridge underwater mt. chain in the oceans
Rift crack
Rift valley flat area btw. ridges

9. New seafloor magma rises up through a rift
6-2 cont.
New seafloor
magma rises up through a rift
Magma cools making new crust
New crust pushes floor apart at ridges

10. 6-3 Evidence of Seafloor Spreading
Trench deep canyons in the ocean floor
Most in the Pacific Ocean
Old crust ends up in trenches
Melts & becomes magma again

11. Subduction zone area where crust is forced down in trenches
6-3 cont.
Subduction zone area where crust is forced down in trenches
Youngest fossils = closest to rift valleys, ridges, & trenches

13. Tectonic plates the lithosphere broken into pieces
6-4 Plate Tectonics
Tectonic plates the lithosphere broken into pieces
7 major plates & 8 minor plates
Asthenosphere liquid part of the mantle

15. Theory of Plate Tectonics explains how & why plates (continents) move
Lithosphere floats on asthenosphere

16. Convection current less dense warm rises & denser cool sinks
6-5 Plate Tectonics
Convection current less dense warm rises & denser cool sinks
3 types of plate boundaries
Convergent
Divergent
Transform

18. Transform 2 plates sliding past each other
6-5 cont.
Transform 2 plates sliding past each other
Cause earthquakes

19. Convergent 2 plates move toward each other
6-5 cont.
Convergent 2 plates move toward each other
Oceanic + continental = oceanic subducts under the continental
Continental + continental = mountain

20. Divergent 2 plates move away from each other
6-5 cont.
Divergent 2 plates move away from each other
Cause rift valleys
Cause seafloor spreading

22. 6-6 Effects of Plate Tectonics
Earthquakes plates slide past each other at a fault
Mountains plates collide & buckle upward

23. Volcanoes oceanic plate dips down & magma collects
6-6 cont.
Volcanoes oceanic plate dips down & magma collects
Hot spots place where magma reaches the surface
Islands plates move over hot spots & volcanoes build