1. Forces in the Earth’s Crust

2. Types of stress Tension, compression, and shearing
Over millions of years these have changed the shape and volume of rock
Most changes occur slowly and cannot be observed directly…. Fast forward over billions of years and you could see………. Stretching, breaking, tilting, folding, and sliding.

4. Tension Stress force that PULLS on the crust
Stretching rock so that it becomes thinner in the middle
Two plates moving apart

5. Compression Stress force that squeezes rock until it folds or breaks
Two plates PUSHING against another

6. Shearing
Stress force that pushes a mass of rock two opposite directions
Causes to break, SLIP apart, change its shape

7. Kinds of faults Most occur along plate boundaries
3 types: normal, reverse, and strike-slip
Normal- tension pulls crust apart
Reverse- compression pushing together
Strike-slip- shearing past each other or up and down

8. Changing Earth’s Surface
Over millions of years the forces can change a flat plain into landforms…
Anticlines, synclines, folded mountains, plateaus

9. Folding Earth’s crust Anticline- rock that bends upward into an arch
Syncline- rock that bends downward into a valley

10. Stretching Earth’s Crust
When two plates move away from each other tension creates 2 normal faults
When these two normal faults form parallel to one another a FAULT BLOCK MOUNTIAN is formed

11. Uplifting Earth’s Crust
Forces that raise mountains can also UPLIFT and form plateaus

12. Compression Convergent Boundary Volcano, Mountains
Tension Divergent Boundary Sea-floor spreading(trenches and ridges), valley
Shearing Transform Fault Boundaries Earthquakes