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Mountains Chapter 9. Stress and Strain Stress is defined as force per unit area. It has the same units as pressure, and in fact pressure is one special.

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Presentation on theme: "Mountains Chapter 9. Stress and Strain Stress is defined as force per unit area. It has the same units as pressure, and in fact pressure is one special."— Presentation transcript:

1 Mountains Chapter 9

2 Stress and Strain Stress is defined as force per unit area. It has the same units as pressure, and in fact pressure is one special variety of stress. However, stress is a much more complex quantity than pressure because it varies both with direction and with the surface it acts on. Strain is defined as the amount of deformation an object experiences compared to its original size and shape. Compression Stress that acts to shorten an object. Tension Stress that acts to lengthen an object. Shear Stress that acts parallel to a surface. It can cause one object to slide over another. It also tends to deform originally rectangular objects into parallelograms The most general definition is that shear acts to change the angles in an object. Normal Stress Stress that acts perpendicular to a surface. Can be either compressional or tensional Hydrostatic Stress (usually compressional) that is uniform in all directions. A scuba diver experiences hydrostatic stress. Stress in the earth is nearly hydrostatic. The term for uniform stress in the earth is lithostatic.

3 Stress-Strain curve Tensile Stress Test Stress and Strain

4 Examples

5 In Geology Conditions Near Earths surface, Temp and Pressure are Low Temperature Higher Temp.  Plastic manner Pressure Time

6 9.1 Geologic Structures Fold is a bend in a rock.

7 Five types of Folds

8 Dome and Basins

9 Examples

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11 Faults

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13 Joints Joints a re fractures in the rock

14 Questions of the Day

15 Question ?

16

17 Mountains Orogeny refers to the process of mountain Building. In a convergent plate boundary: Folding, faulting of rocks, earthquakes, volcanic eruptions, intrusion of plutons and metamorphism. The motor of Orogeny is sudduction

18 Island Arcs Island Arc is volcanic mountain chain that forms where 2 plates carrying oceanic crust converge

19 The Andes

20 Himalayas Continent-Continent Collision

21 Himalayas

22 The Wilson Cycle Homework 5 Describe The Wilson Cycle Due: Monday 4/8/13


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