1. Evidence From Earth
Life on Earth depends on our planet to supply the conditions needed to support them.

2. I. Types of Plate Boundaries
A. Divergent –
1. Moving away from each other
2. frequent earthquakes at boundary
3. where 2 ocean plates diverge –
a. Magma rises up to surface - forms midocean ridge
b. New crust is formed of basalt (youngest rocks)
c. deep sea vents – underwater geysers
4. where 2 continental plates diverge-
a. rift valleys

4. African Rift & Earthquakes

5. I. Types of Plate Boundaries
B. Convergent –
1. plates come together (crash into each other)
a. more dense plate pushed down into magma(subduction)
2. both plates continental = same density = high mountains

6. I. Types of Plate Boundaries
B. Convergent –
3. oceanic plate & continental plate =
a. oceanic plate pushed down forming ocean trench off coast
b. continental plate - magma breaks through continental crust adds to mountain = granite
Pink = new
Orange =
Current
Volcano

7. I. Types of Plate Boundaries
C. transform –
1. plates slide past each other
2. grinding up rock created trenches or valleys (low elevation)
3. wide area of earthquakes surround boundary
4. NO magma flows up….NO new rock formed

9. plate boundaries.

10. II. Destruction of Earths Crust
A. Subduction –
1. oceanic plate pushed under continental plate
- continental plate less dense ‘floats’
2. plate pushed down into magma & melts
B. Erosion-
1. weathering wind & water break rock up into sediments
(sand,clay)
2. transform boundaries grind up rock

11. III. Creation of Earths Crust
A. Magma moves to surface and cools to form new rock
1. in ocean rifts basalt forms new oceanic crust
(divergent boundaries)
2. magma flows up through continental crust to form granite
(convergent boundaries)

12. IV.
A. Subduction –

13. II. Destruction of Earths Crust
A. Subduction –

14. II. Destruction of Earths Crust
A. Subduction –