Interactions at Plate Boundaries: Stress, Deformation, and California Geology

2. Chapter Menu Lesson 1:Interaction at Plate Boundaries Lesson 2:California Geology Click on a hyperlink to view the corresponding lesson.

3. 5.1 Interactions at Plate Boundaries fracture fault divergent plate boundary continental rifting rift valley convergent plate boundary subduction transform plate boundary

4. 5.1 Interactions at Plate Boundaries Stress and Deformation • Earth’s lithosphere is made up of crust and upper mantle that are broken into plates. • Each plate travels at different speeds and in different directions. • Collisions between plates causes stress at plate boundaries, resulting in deformation.

5. 5.1 Interactions at Plate Boundaries Stress and Deformation (cont.)

6. 5.1 Interactions at Plate Boundaries Deforming Rocks • Plastic deformation occurs when rocks change shape by folding under high temperatures and pressure. • Elastic deformation occurs when rocks resume their original shapes after the stress is removed.

7. 5.1 Interactions at Plate Boundaries Deforming Rocks (cont.) • A fracture is a break or crack in rock. • If rock on side of a fracture has moved relative to the other side it is called a fault.

8. 5.1 Interactions at Plate Boundaries Types of Stress • Three main types of stress: • Tension: rocks are stretched • Compression: rocks are squeezed • Shear: rocks slide horizontal in opposite directions

9. 5.1 Interactions at Plate Boundaries Types of Stress (cont.)

10. 5.1 Interactions at Plate Boundaries Types of Faults • Three main types of faults: • Normal faults • Reverse faults • Strike-slip faults

11. 5.1 Interactions at Plate Boundaries Normal Faults • Normal faults result from tension stress and slope at an angle.

12. 5.1 Interactions at Plate Boundaries Reverse Faults • Reverse faults result from compression stress and slope at an angle.

13. 5.1 Interactions at Plate Boundaries Strike-Slip Faults • Strike-slip faults result from shearing stress and are often vertical.

14. 5.1 Interactions at Plate Boundaries Types of Plate Boundaries • Divergent plate boundary occurs when two lithospheric plates move apart. • Convergent plate boundaries form when two lithospheric plates move toward each other.

15. 5.1 Interactions at Plate Boundaries Divergent Plate Boundaries • Mid-ocean ridges occur along divergent plate boundaries.

16. 5.1 Interactions at Plate Boundaries Divergent Plate Boundaries (cont.) • Continental rifting occurs when two continental plates are being pulled apart. • East African Rift • Gulf of California

17. 5.1 Interactions at Plate Boundaries Convergent Plate Boundaries • Three possible interactions: • Ocean-to-ocean: two oceanic plates move towards each other—subduction occurs as one plate is forced down into the mantle beneath another plate • Ocean-to-continent: oceanic plate subducts beneath continental plate • Continent-to-continent: compression stresses force crust to rise up, thicken, and shorten

18. 5.1 Interactions at Plate Boundaries Convergent Plate Boundaries (cont.)

19. 5.1 Interactions at Plate Boundaries Transform Plate Boundaries • A transform plate boundary exists when two plates slide horizontally past one another.

20. 5.1 Interactions at Plate Boundaries Transform Plate Boundaries (cont.) • Oceanic transform plate boundaries connect pieces of the mid-ocean ridges. • Transform plate boundaries can slice through continental lithosphere as strike-slip faults. • Large earthquakes can occur on these faults and can be very destructive. Where do most earthquake epicenters and volcanoes occur?

21. 5.1 Interactions at Plate Boundaries Lesson 1 Review • A • B • C • D What type of deformation results from tension? A thickening of the lithosphere B compression of the lithosphere C thinning of the lithosphere D movement of rocks past each other

22. 5.1 Interactions at Plate Boundaries Lesson 1 Review • A • B • C • D Subduction results from _____. A one oceanic plate being forced into the mantle beneath another plate B two plates moving away from each other C two continental plates colliding with each other D two continental plates sliding horizontally past each other

23. 5.1 Interactions at Plate Boundaries Lesson 1 Review • A • B • C • D What type of plate boundary separates the North American and Pacific Plates in California? A convergent B rift C transform D divergent

24. End of Lesson 1

25. 5.2 California Geology San Andreas Fault

26. 5.2 California Geology Plate Tectonics in California • A continental transform plate boundary cuts across California. • A convergent plate boundary resides off the northern shore of California. • This active plate tectonic setting produces earthquakes, volcanoes, and mountains.

27. 5.2 California Geology 80 Million Years Ago

28. 5.2 California Geology Transform Plate Boundary • The San Andreas Fault is a transform plate boundary between the North American and Pacific Plates. • This boundary switches to an oceanic transform boundary when it goes out to sea.

29. 5.2 California Geology Convergent Plate Boundaries • Two small oceanic plates are being subducted in the Cascadia Subduction Zone. • This subduction zone forms a convergent plate boundary.

30. 5.2 California Geology California’s Mountains • California’s mountains often formed from interactions at several plate boundaries.

31. 5.2 California Geology Subduction • The Klamath Mountains, Costal Ranges, peninsulas, and Sierra Nevada all contain igneous and metamorphic rocks formed below the surface. • These rocks were formed when an ancient oceanic plate subducted beneath the North American Plate.

32. 5.2 California Geology Rifting • Some mountains in California have formed from tension stress. • The Panamint Range is rising up as the crust in eastern California stretches.

33. 5.2 California Geology Lesson 2 Review • A • B • C • D Convergent plate boundaries in California are important in _____. A the development of California’s rift valleys B the formation of California’s mountains C movement along the San Andreas Fault D the existence of the Gulf of California

34. 5.2 California Geology Lesson 2 Review • A • B • C • D The San Andreas Fault is a transform plate boundary; this also makes it a _____. A subduction zone B convergent plate boundary C rift valley D strike-slip fault

35. 5.2 California Geology Lesson 2 Review • A • B • C • D Which of the following are active Californiavolcanoes? A Lassen Peak and San Andreas B Sierra Nevada and Mount Shasta C Lassen Peak and Mount Shasta D Panamint Range and Mount Shasta

36. End of Lesson 2

37. Chapter Resources Menu Chapter Assessment California Standards Practice Image Bank Science Online Interactive Table Virtual Lab Click on a hyperlink to view the corresponding feature.

38. Chapter Assessment 1 • A • B • C • D What does shearing stress produce when plates slide past each other? A subduction zones B strike-slip faults C divergent plate boundaries D rift valleys

39. Chapter Assessment 2 • A • B • C • D Where do mid-ocean ridges usually occur? A convergent plate boundaries B strike-slip faults C divergent plate boundaries D normal faults

40. Chapter Assessment 3 • A • B • C • D In what areas of the Earth does present-day continental rifting occur? A eastern Africa and western South America B the Gulf of California and eastern South America C Gulf of California and the Himalayas D eastern Africa and the Gulf of California

41. Chapter Assessment 4 • A • B • C • D Which two oceanic plates are being subducted in the Cascadia Subduction Zone? A San Andreas and Juan de Fuca BJuan de Fuca and Gorda C Gorda and San Andreas D San Andreas and Pacific

42. Chapter Assessment 5 • A • B • C • D The San Andreas Fault is a(n) _____. A strike-slip fault B oceanic transform plate boundary C subduction zone D rift valley

43. SCI 1.f CA Standards Practice 1 • A • B • C • D Northern California is located _____. A above a subduction zone B below a subduction zone C above a rift valley D below a rift valley

44. CA Standards Practice 2 SCI 1.e • A • B • C • D Which of the following scenarios would most likely result in the development of mountains? A two oceanic plates pulling apart B two continental plates colliding C one oceanic and one continental plate colliding D erosion by wind and water

45. CA Standards Practice 3 SCI 7.g • A • B • C • D The Pacific Plate moves about 3.4 cm/year relative to the ____. A Atlantic Plate B San Andreas Plate C North American Plate D Gorda Plate

46. CA Standards Practice 4 SCI 1.e • A • B • C • D What is subduction? A the process in which one plate is forced down into the mantle beneath the other plate B the result of two plates moving away each other C the process of two continental plates colliding D the result of two plates sliding sideways past each other

47. CA Standards Practice 5 SCI 1.e • A • B • C • D Deformation that results from compression stress is _____. A the thickening of the lithosphere B the melting of the rocks C the thinning of the lithosphere D always minimal

48. Image Bank

49. Interactive Table

50. End of Resources