Athletic field in Taiwan

6.1 Forces in Earth’s Crust Stress: a force that acts on rock to change its shape or volume. (This may take millions of years) 3 Types of Stress: 1. Tension: pulls on the crust stretching rock so that it becomes thinner in the middle

2. Compression: squeezes rock until it folds or breaks 3 2. Compression: squeezes rock until it folds or breaks 3. Shearing: pushes a mass of rock in 2 opposite directions

Faults: occur along plate boundaries, where the forces of plate motion push or pull the crust so much that the crust breaks 3 types of faults 1. Normal fault: tension in Earth’s crust pull rocks apart; hanging wall slides downward footwall hanging wall

2. Reverse fault caused by compression in the crust, the hanging wall slides upward 3. Strike-slip fault rocks on either side move past each other sideways with little up –or –down motion

Normal Fault Reverse Fault Strike-Slip fault

Changing Earth’s surface: over millions of years, the forces of plate movement can change a flat plain into land forms such as *anticline- upward fold in rock formed by compression *syncline- downward fold in rock formed by compression *plateau- large area of flat land elevated high above sea level Anticline Syncline

*Folded mountains- where 2 plates collide Alps in Europe and Himalayas in Asia *Fault-Block mountains – where 2 faults parallel to each other pull apart, each side slides down Part of the Rockies