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Geology Chapter 11 – Mountain Building
Michael Wysession Washington University
Big Ideas Mountains provide evidence of enormous tectonic forces within Earth, which are usually associated
with the boundaries between lithospheric plates.
Space and Time Mountains primarily form by folding and faulting rock at compressional plate boundaries, by
faulting rock at tensional plate boundaries, by uplifting the lithosphere, and through volcanism.
Forces and Motion Rock deforms in an elastic, brittle, or ductile manner, depending upon the type and amount
of stress, the applied temperature and pressure, the type of rock, and the amount of time it is stressed. Stress can
be tensional, compressional, or shear. Folds, such as anticlines and synclines, occur when rock strains in a
ductile manner. Faults, in the form of normal, reverse, and strike-slip, occur when rock deforms in a brittle
manner.
Matter and Energy The world's longest mountain chain is of volcanoes along the interconnected divergent
plate boundaries of the mid-ocean ridges. At ocean-ocean convergent plate boundaries, volcanic mountains
form an island arc. At an ocean-continent convergent boundary, mountains form from composite volcanoes and
accreted sediments. At continent-continent boundaries, mountains form from folded continental crust and the
accretion of sediments, island arcs, continental fragments, and slivers of ocean crust.
Earth as a System Because of isostasy, mountains have deep crustal roots, and buoy upward when the tops are
eroded. Continents like North America have grown in size through the accretion of land at their edges during
plate collisions.
Section 1 – Rock Deformation
1. Every body of _________________, no matter how _________________, has a point at which it will
_________________ or _________________.
2. What is deformation?
3. Where does most deformation occur?
4. _________________ motions and interactions at plate _________________ creates forces that cause rock to
_________________.
5. What is stress?
6. Define strain.
7. List the factors that influence the strength of a rock and how it will deform.
8. What are the two ways rocks deform permanently.
9. Describe brittle deformation.
10. Describe ductile deformation.
11. How does the rock type affect how it will deform?
12. Describe how time affects how rocks will deform.
13. List and briefly describe the three types of stress that rocks commonly undergo.
14. What are folds?
15. What are the three main types of folds?
16. Describe anticlines.
17. Describe synclines.
18. Describe monoclines.
19. What is a fault?
20. What is the hanging wall?
21. What are the three major types of faults?
22. Describe normal faults.
23. What are reverse faults?
24. What is a thrust fault?
25. Describe strike-slip faults.
26. Define joints.
Section 2 – Types of Mountains
27. What is the collection of processes that produce a mountain belt called?
28. What is the most obvious sign of forces that create mountains? List some other factors involved.
29. How can mountains be classified?
30. Describe folded mountains.
31. Give three examples of folded mountains.
32. Describe fault-block mountains.
33. Give two examples of fault-block mountains.
34. What is a graben?
35. What is a horst?
36. Describe what a dome is.
37. Give an example of a dome mountain.
38. Where are the oldest rocks found in a dome?
39. What are basins?
40. Give an example of a basin in the United States.
41. Where are the oldest rocks found in basins?
Section 3 – Mountain Formation
42. Where does most mountain building occur?
43. _________________ plates provide the _________________ forces that fold, fault, and metamorphose the
thick layers of sediments deposited at the edges of _________________.
44. Describe ocean-ocean convergence.
45. What does ocean-ocean convergence mainly produce?
46. _________________ building along _________________ margins involves the convergence of an
_________________ plate and a plate whose leading edge contains _________________ crust.
47. What do the Andes Mountains show?
48. What is a accretionary wedge?
49. What does ocean-continental convergence produce?
50. Describe the two parallel belts produced by ocean-continental convergence.
51. What are the two types of mountains formed by ocean-continental convergence?
52. At a _________________ boundary between two plates carrying _________________ crust, a collision
between the _________________ fragments will result in _________________ mountains.
53. Give two examples of this type of convergence.
54. Why can’t continental crust be subducted?
55. What type of mountain form along the ocean ridges at divergent plate boundaries?
56. Where is the longest mountain range?
57. What is one type of mountain that can form away from the plate boundaries?
58. Describe accretion.
59. What is a terrane?
60. What could many terranes have been before they collided with continents?
61. The _________________ of larger _________________ fragments, such as mature _________________,
may result in a mountain range.
62. Where does the idea that mountain building occurs in connection with accretion of crustal fragments to a
continental mass come from?
63. In addition to the _________________ movements of lithospheric plates, gradual _________________
motions of the crust are seen in many locations around the globe.
64. What is isostasy?
65. Describe isostatic adjustment.
66. How are ice sheet related to isostatic adjustment?
67. What will happen because of isostasy?
68. The process of uplifting and erosion will continue until what happens?