Earth Science Ch. 20 Mountain Building Reading Activity

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Earth Science, 12e

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Earth Science, 12e

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1. Globe Science, 12e Mountain BuildingChapter x

2. Deformation • Deformationis a full general term that refers to all changes in the original form and/or size of a rock trunk • Most crustal deformation occurs along plate margins • Factors that influence the strength of a rock • Temperature and confining pressure • Rock type • Time

3. Folds • Rocks bent into a series of waves • Most folds event from compressional forces that shorten and thicken the crust • Types of folds • Anticline – upfolded, or biconvex, stone layers • Syncline– downfolded rock layers

4. Folds • Types of folds • Anticlines and synclines can be • Symmetrical – limbs are mirror images • Asymmetrical – limbs are not mirror images • Overturned – ane limb is tilted beyond the vertical • Where folds dice out they are said to be plunging

5. A series of anticlines and synclines Figure 10.3

6. Plunging folds Figure 10.4 A

7. Outcrop patterns of plunging folds Figure 10.4 B

8. Folds • Types of folds • Other types of folds • Dome • Circular, or slightly elongated • Upwarped displacement of rocks • Oldest rocks in core • Basin • Round, or slightly elongated • Downwarped displacement of rocks • Youngest rocks in core

9. The Black Hills of Due south Dakota are a large dome Effigy 10.6

10. The bedrock geology of the Michigan Basin Figure 10.7

11. Faults • Faultsare fractures (breaks) in rocks forth which appreciable displacement has taken place • Types of faults • Dip-slip fault • Movement along the inclination (dip) of fault plane • Parts of a dip-skid fault • Hanging wall – the rock higher up the mistake surface • Footwall – the rock below the error surface

12. Concept of hanging wall and footwall along a fault

13. Faults • Types of faults • Dip-sideslip fault • Types of dip-sideslip faults • Normal fault • Hanging wall block moves downward • Associated with fault-block mountains • Prevalent at spreading centers • Caused past tensional forces

14. A normal fault Figure 10.ix A

15. Error block mountains produced by normal faulting Figure 10.10

16. Faults • Types of faults • Dip-slip fault • Types of dip-slip faults • Reverseandthrust faults • Hanging wall cake moves up • Caused by potent compressional stresses • Reverse fault - dips greater than 45º • Thrust fault - dips less than 45º

17. A reverse fault Figure 10.9 B

18. A thrust error Effigy 10.9 C

19. Faults • Types of faults • Strike-slip faults • Dominant displacement is horizontal and parallel to the trend, or strike • Transform error • Large strike-slip error that cuts through the lithosphere • Oft associated with plate boundaries

20. A strike-slip fault Figure 10.nine D

21. Faults • Types of faults • Joints • Fractures forth which no appreciable displacement has occurred • Most are formed when rocks in the outermost crust are deformed

22. Mountain belts • Orogenesis refers to processes that collectively produce the "classic" mountain belt • Orogeny e'er begins with Subduction • Mount building at convergent boundaries • Most mountain building occurs at convergent plate boundaries

23. Mount belts • Mountain building at convergent boundaries • Passive margins • Prior to the germination of a subduction zone • e.k., East Declension of Due north America • Passive margin evolves into convergent boundary

24. Mountain belts • Mountain edifice at convergent boundaries • Andean-type mount building • Types related to the overriding plate • Active continental margins • Subduction zone forms • Deformation process begins • Continental volcanic arc forms • Accretionary wedge forms • Examples of inactive Andean-type orogenic belts include Sierra Nevada Range and California'southward Coast Ranges

25. Orogenesis along an Andean-type subduction zone Figure 10.15 B

26. Orogenesis along an Andean-blazon subduction zone Effigy 10.xv C

27. Mountain belts • Mount edifice at convergent boundaries • Continental collisions • Where two plates with continental crust converge • e.grand., India and Eurasian plate collision • Himalayan Mountains and the Tibetan Plateau

28. Formation of the Himalayas Effigy 10.xix A

29. Germination of the Himalayas Figure 10.19 B

30. Mount belts • Mountain building at convergent boundaries • Continental accretion • 3rd mechanism of mountain building • Small crustal fragments collide with and accrete to continental margins • Accreted crustal blocks are called terranes • Occurred forth the Pacific Declension

31. Distribution of modern-day oceanic plateaus and fragments Figure 10.xvi

32. Accreted terranes along the western margin of North America Figure 10.xviii

33. Mountain belts • Buoyancy and the principle of isostasy • Bear witness for crustal uplift includes wave-cutting platforms loftier above bounding main level • Reasons for crustal uplift • Not and so piece of cake to determine • Isostasy • Concept of a floating chaff in gravitational balance • When weight is removed from the crust, crustal uplifting occurs • Procedure is called isostatic adjustment

34. The principle of isostasy Effigy ten.23

35. Erosion and resulting isostatic aligning of the crust Figure ten.24 AB

36. Erosion and resulting isostatic adjustment of the crust Figure 10.24 BC

37. End of Chapter x

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