BELLWORK

1. BELLWORK • Name the 3 types of plate boundaries and an example of each.

2. Deforming the Earth’s Crust

3. Moving Continents • http://www.suu.edu/faculty/colberg/hazards/platetectonics/18_Pangaea.html

4. Tracking Tectonic Plates Scientists use GPS to track plate movement. Radio waves are beamed from satellites to GPS ground stations which record their position.

5. 3 Possible Driving Forces • Convection Currents • Ridge Push and Slab Pull • Ridge Push– At mid-ocean ridges, the oceanic lithosphere is higher than it is where it sinks into the asthenosphere. Because of ridge push, the oceanic lithosphere slides downhill under the force of gravity. • Slab Pull – Because oceanic lithosphere is denser than the asthenosphere, the edge of the tectonic plate that contains oceanic lithosphere sinks and pulls the rest of the tectonic plate with it in a process called slab pull.

6. Plate movement causes geological events such as mountain formation, volcanic eruptions, and earthquakes.

7. Deformation • The process by which the shape of a rock changes because of stress. • Stress is the amount of force per unit area on a given material. • Different things happen to rock when different types of stress are applied. • Rock layers bend when stress is placed on them. • When enough stress is placed on rocks, they can reach their elastic limit and break.

8. Compression • The type of stress that occurs when an object is squeezed, such as when two tectonic plates collide. • When compression occurs at a convergent boundary, large mountain ranges can form.

9. Tension • Stress that occurs when forces act to stretch an object • Tension occurs at divergent plate boundaries, such as mid-ocean ridges, when two tectonic plates pull away from each other.

10. Folding • The bending of rock layers because of stress in the Earth’s crust. • Types of Folds – depends on how the rock layers deform: • Anticlines • Synclines • Monoclines

11. Anticline • Upward-arching folds. • Caused by horizontal stress.

12. Syncline • Downward, troughlike folds. • Caused by horizontal stress.

13. Monocline • Fold where both ends are horizontal. • Cause by vertical stress.

14. Faulting • The surface along which rocks break and slide past each other. • Some rock layers break when stress is applied • The blocks of crust on each side of the fault are called fault blocks.

15. Footwall & Hanging Wall • When a fault is not vertical, its two sides are either a hanging wall or a footwall.

16. Normal Fault • When a normal fault moves, it causes the hanging wall to move down relative to the footwall. • Caused by rocks being pulled apart (tension).

17. Normal Fault

18. Reverse Fault • When a reverse fault moves, it causes the hanging wall to move up relative to the footwall. • Caused when rocks are pushed together (compression).

19. Reverse Fault

20. Strike-Slip Fault • When opposing forces cause rock to break and move horizontally.

21. Mountain Building • When tectonic plates undergo compression or tension, they can form mountain ranges in several ways.

22. Folded Mountains • The highest mountains in the world are formed when rock layers are squeezed together and pushed upwards to form folds. • This occurs at convergent boundaries where plates collide. • The plates buckle and thicken. • The continental crust is pushed upward, forming mountains.

23. Examples of Folded Mountains • Himalayas

24. Alps In central Europe

25. Ural Mountains in Russia

26. Great Smoky Mountains

27. Fault-Block Mountains • Form when large blocks of the Earth’s crust drop down relative to other blocks. • Tension produces mountains that have sharp, jagged peaks.

28. Examples of Fault-Block Mountains • Teton Range in Wyoming.

29. Sierra Nevada mountain range in California

30. Harz Mountains in Germany

31. Volcanic Mountains • Form when magma rises to the Earth’s surface and erupts.

32. Examples of Volcanic Mountains • Mount St. Helens in Washington

33. Mount Pinatubo in the Phillipines

34. Uplift and Subsidence • Uplift is the rising of regions of the Earth’s crust to higher elevations. • Rebound – When the crust slowing springs back to its previous elevation, as when a glacier melts. • Subsidence is the sinking of regions of the Earth’s crust to lower elevations. • Rocks that are hot take up more space than cooler rocks.

35. Tectonic Letdown • Subsidence can also occur when the lithosphere becomes stretched in rift zones.

36. Quiz • Name the 3 types of faults. • Name the 3 types of folds. • What is compression? • What is tension? • Would you find a folded mountain at a mid-ocean ridge? Why or why not?