1. Forces of Change
With a partner, brainstorm a list forces that change the surface of our planet.

2. Earth is a Layered Planet…
Core - center of planet, very hot
Inner = solid
Outer = liquid
Mantle - layer of hot, dense rock (solid & liquid)
Crust - outer layer, rocky shell

4. Plate Tectonics
Continental Drift - theory that all continents were once joined but later drifted apart.
Pangaea - super continent
Plate Tectonics - plates move slowly to create many of Earth’s physical features.

5. RING OF FIRE!

6. Internal Forces Mountains – formed when continental plates collide
Subduction - heavy sea plate dives under light continental plate.
Volcanoes - sea plate becomes magma and bursts through crust to form mountains (Andes)

7. Internal Forces…
Folds are caused when moving plates squeeze Earth’s surface until it buckles
Faults occur when plates slide past each other, creating cracks
San Andreas Fault
Earthquakes are sudden, violent movements of tectonic plates along a fault line.

8. External Forces of Change
Weathering (No movement)
Physical – rock is broken into fragments by wind or water
Chemical – changes the chemical makeup of rocks
Acid Rain
Erosion (Movement)
Wind – involves the movement of dust/sand/soil
Glacial – large bodies of ice that carve Earth’s surface
Water – flow of water wears away rock/soil
Source:

13. Questions?
Write a summary that explains the forces that change the earth (make sure to include examples in your summary).