2. Dr. Jeff Amato Geological Sciences 8/26/08 GEOL 470 Structural Geology OUTLINE Why structure is important An example of structural analysis Earth Structure

3. Time Scale

4. Why study structural geology?

5. How do we explain the major features of the Earth?

7. Why are there mountains? Matterhorn, Swiss Alps

8. How can solid rock flow like taffy? Morcles Nappe, Swiss Alps

9. Where is the oil?

10. How do faults relate to earthquakes Active mountain. front, Basin and Range Province, Nevada

11. Structural Hazards and Society

12. Structural analysis of a pizza…

13. It all starts with field mapping Brooks Range Foothills, AK

14. A basic tool: the geologic map

15. A structural cross section: Determine deep structure from surface data

16. Summary: Structures include: Folds, faults, joints Foliations, lineations, shear zones Structures are found at every scale Plate, mountain, outcrop, hand sample, thin section

17. Summary: Structural geology is important to society Helps to find resources and determine hazards

18. Summary: Structural analysis is conducted through observation and interpretation: Kinematics: What moved? How much? What direction? Dynamics: What forces and stresses were responsible?

19. Summary: Geologic maps and cross-sections help visualize the big picture

20. Earth Structure

21. How many layers in the earth? Two answers to this…

22. 1) Compositional Classification Each layer has same basic composition.

23. Crust

24. Mantle

25. Crust= low density rock Mantle = high density rock Core= iron

28. 2) Mechanical Classification Each layer will consist of material that behaves the same way under stress

30. Outer Core= liquid Inner Core= solid

31. Mechanical Classification LithosphereSolid plates, resistant to flow Plates are moving AsthenosphereSolid: flows under stress Convection! Outer Core Inner Core Liquid Solid

34. Oceanic crust vs. Continental crust

39. Why are the oceans deep, and the continents at high elevations?

40. What is density? (  ) mass (g) == volume (cm 3 )

41. Density of different materials Water: 1 g/cm 3 Quartz: 2.3 g/cm 3 Rocks:2-3.5 g/cm 3 Iron: 8 g/cm 3 Lead: 11 g/cm 3 Gold: 19 g/cm 3

42. Density of different materials Quartz: 2.3 g/cm 3 Gold: 19 g/cm 3

43.  = 0.9 g/cm3  = 1.0 g/cm3

44. 0 (km) Continental crust (2.8 g/cm 3 ) Moho discontinuity Horizontal distance not to scale Mantle (3.4 g/cm 3 ) Oceanic crust (3.0 g/cm 3 ) 10 20 30 40 50 Less dense continental crust floats on denser mantle. Continental crust is less dense than oceanic crust.