1. Introduction to Faults (p. 269-279; 286-296) 1) Hanging wall vs. footwall 2) Fault names: based on geometry & kinematics 3) Characteristics and terminology -Strike-slip faults -Normal faults -Thrust faults

2. Fault: Fractures along which there is visible offset by shear displacement; generally planar or curviplanar

3. Strike-slip faults: Accommodate horizontal slip between adjacent blocks left lateral vs. right lateral: sense-of-slip relative to a chosen block left lateral (sinistral) right lateral (dextral)

4. What is it? left lateral vs. right lateral Las Vegas shear zone

5. What is it?

6. What is it? (interpretation) left-lateral strike-slip fault

7. Hanging wall: The block toward which the fault dips. Footwall: The block on the underside of the fault.

8. Normal fault: hanging wall moves down with respect to footwall

9. Normal faults generally place younger and/or lower-grade rocks (in HW) on top of older and/or higher-grade rocks (in FW) Tertiary conglomerate Cambrian limestone HW FW

10. high-grade gneiss young “dirt” FW HW Normal faults generally place younger and/or lower-grade rocks (in HW) on top of older and/or higher-grade rocks (in FW)

11. Thrust fault (reverse fault): hanging wall moves upward relative to footwall HW FW

12. Thrust faults generally place older and/or higher-grade rocks (in HW) on top of younger and/or lower-grade rocks (in FW)

14. HW FW blueschist sandstone

15. Normal faults accommodate lengthening

16. Thrust faults accommodate shortening

17. http://earth.leeds.ac.uk/learnstructure/index.htm

18. Slip vs. Separation Slip: actual relative displacement Separation: apparent relative displacement

19. A real example of apparent separation vs. true slip!

20. The key to describing slip along a fault lies in measuring (1) Direction of displacement (2) Sense of displacement (3) Magnitude of displacement

21. Listric: curved faults that flatten with depth

22. Fault scarp: results when a fault displaces the ground surface

23. Map Symbols: a start -Strike-slip fault -Normal fault -Thrust fault -Fault dip and slip vector

24. Next lecture: Intro to folds Read pp. 372-413

25. Important terminology/concepts Faults- how are they defined? Hanging wall Footwall Strike-slip fault; left-lateral (sinistral) vs. right-lateral (dextral) Normal faults: younger/lower grade on older/higher grade Lengthening Thrust faults: older/higher grade on younger/lower grade Shortening Slip vs. Separation? Drag fold Listric Fault scarp