1. Unit 3
Plate Tectonics

2. Deformation of Earth’s Crust
Unit 3
Deformation of Earth’s Crust

3. Stress and Strain
Stress is a force that causes movement or deformation.
Movement or deformation resulting from stress is called strain

4. Tension, Compression, Shearing
Tension: Pulling force that stretches an object and tries to pull it apart
Example: Towing a car with a chain.
Compression: Pushing force that squeezes an object and tries to squash it
Example: Crushing a soda can with your foot.
Shear: Pushing or pulling forces not directly opposing each other
Example: Cutting a piece of paper with scissors.

5. Brittle vs. Ductile Brittle objects break when force is applied.
Ductile objects bend or stretch when force is applied.
Rocks at or near earth’s surface are more brittle than rocks deeper rocks
Most earthquakes occur in earth’s brittle lithosphere.

6. Folding
Folding happens when two pieces of a plate come together and push against each other.
The high points of the folds are called anticlines.
The low points of the folds are synclines.

7. Fold Types

8. Faulting
Faults are fractures in the earth’s lithosphere along which movement, or displacement has occurred.
As the tectonic plates move, the rock is deformed until it ruptures along a fault and energy is released.
Displacement of rocks along a fault is a direct cause of earthquakes.

9. Fault Types

10. Hanging Wall and Footwall