1. The Earth’s Fractured Surface
PLATE TECTONICS
The Earth’s Fractured Surface

2. PLATE TECTONICS
PLATE TECTONICS = the study of the movement of plates and the effects they have on the surface of the earth.

3. PLATE TECTONICS
New discoveries about the earth’s interior in the 1960s:
Lithosphere is not one piece, rather it is broken into plates (plate = a slab of lithosphere that has definite boundaries or edges)

4. Major Plates of the Lithosphere Figure 6.1 pg 87

5. PLATE TECTONICS The plates are constantly in motion. HOW?
The plates are set in motion by the convection currents in the asthenosphere
The earth’s heat engine heats the rock and causes it to swirl (rising when heated and sinking when cooled)

6. PLATE TECTONICS

7. PLATE TECTONICS How do we know where the plate boundaries are?
The boundaries occur along the major earthquake belts of the world
These plates are hitting against one another
Quakes seldom occur in the interiors of the plates
– Earthquake video

8. Major Plates of the Lithosphere Figure 6.1 pg 87

9. World Earthquake Epicentres Figure 6.3 pg 88

10. PLATE BOUNDARIES (Earthquakes)
There are 3 main types of plate boundaries (which cause folding, faulting, and vulcanism):
CONVERGING – two plates that are moving towards each other. Two types of converging boundaries include:
Collision – where two plates containing continents are meeting

11. Collision Zone Between Two Continental Plates Figure 6.19 pg 104

12. PLATE BOUNDARIES
Subduction – where an oceanic plate is sinking below a plate containing continents
30-34

13. PLATE BOUNDARIES
DIVERGING – develop where two plates are moving apart or separating from one another.

14. PLATE BOUNDARIES
TRANSFORM FAULT BOUNDARIES – two plates are slipping and sliding past one another.

15. Transform San Andreas Fault Figure 6.13 pg 98

16. Orchard Offset Along San Andreas Fault, California Figure 6.16 pg 101

17. PLATE TECTONICS
Plate movements produce 3 tectonic processes that change the surface of the lithosphere:
Folding – bends and twists the rocks due to compression and squeezing from two plates moving together
Faulting – rocks move past each other along a crack, plates are sliding past one another, or moving together

18. PLATE TECTONICS
Vulcanism – movement of magma beneath the earth’s surface. Plates are separating or coming together
** All 3 of the above movements combine to create major mountain chains (i.e. the Rockies, the Andes, etc.)

19. PLATE TECTONICS (Volcanoes)
HOT SPOTS = strong upward currents of magma in the upper mantle that “burn a hole” through the plate creating a volcano
Hot spots are not always related to the plate boundaries
More related to areas where there is lots of magma in the upper mantle

20. https://www.youtube.com/watch?v=WwBVG0Si7rs – Hawaii Erruption
World Hot Spots Figure 6.4 pg 89

21. Rock Types Original molten rock from deep within the earth
Igneous
Original molten rock from deep within the earth
Impervious to water (water cannot soak through it)
Two types:
Extrustive
Cools very fast, created by lava
Intrusive
Cool very slowly, created by Magma below the earths surface
Basalt
Granite

22. Rock Types Sedimentary Sandstone
Broken pieces of rock carried away by erosion and deposited in layers and compressed by the weight above
Erosion = the gradual wearing away of land or rock by natural forces (i.e. wind, water, etc)
Sandstone

23. Rock Types Metamorphic Marble
Rock that has been transformed by intense heat and/or pressure
Molecular structure of the rock is slightly altered to give it a different form
Marble

24. Rock Cycle Summary Rocks can be transformed through the rock cycle.
Rock can be created from hot, melted magma that rises from the Earth’s crust. It cools and hardens to form igneous rock. This rock may be broken down into particles or sediment. Eventually the sediment hardens to form sedimentary rock. Pressure and heat can cause this rock to melt again forming metamorphic rock. (This may contain valuable resources.)