1. 12 October 2004GLG310 Structural Geology

2. 12 October 2004GLG310 Structural Geology Today’s lecture Application exercise Announcements Information about the research assignment Faults and stress

3. 12 October 2004GLG310 Structural Geology Announcements No field trip on this Thursday, but yes on October 21! Note some schedule changes on the web site.

4. 12 October 2004GLG310 Structural Geology Information about research assignment This assignment, due on December 2, will be 3-5 pages of double- spaced typed text (12 pt font like Times Roman). The assignment is to make some structural observations and measurements, or even a small geologic map, for any nearby geologic locality (of your choosing) and explain the geometry and deformation and interpret it in terms of geologic history and geologic processes. The paper must include at least 2 figures (they don't count towards the length) illustrating some aspect of your research. These figures can be anything (cartoon, sketch, simplified geologic cross-section, geologic map), but should be something you illustrate yourself. It should be neat, perhaps colored, but need not be drafted. You will also prepare and present (5 minutes) a poster, consisting of several figures, a summary, and bullet lists outlining key points about your research project.

5. 12 October 2004GLG310 Structural Geology Research assignment review Two classmates must review your written paper before turning it in. Your should give them a typed, double- spaced draft of your paper and drafts of the figures and they will write corrections and suggestions on the draft, and then sign the bottom. You should incorporate their suggestions (at least those that are valid) into your final paper, and turn in the copies of your classmate's reviews along with your final paper. One of the best ways to write is edit someone else's writing. You will lose points if you do not get two meaningful reviews on a typed draft (not the final draft) of your paper--someone simply signing your final paper but making no comments or saying "Good job" is not a sufficient review!

6. 12 October 2004GLG310 Structural Geology Faults and stress: traction and stress Mohr Circle Graphical construction that lets us visualize the relationship between the principal stresses and tractions on a boundary (like a fault).  measured positive clockwise from  1 direction clockwise to plane of interest 2  measure positive clockwise from –  n direction on Mohr circle

7. 12 October 2004GLG310 Structural Geology Faults and stress: traction and stress Equations of the Mohr Circle (also “Cauchy’s equations”)

8. 12 October 2004GLG310 Structural Geology 90 Faults and stress: traction and stress

9. 12 October 2004GLG310 Structural Geology Faults and stress: traction and stress

10. 12 October 2004GLG310 Structural Geology Faults and stress: traction and stress

11. 12 October 2004GLG310 Structural Geology Faults and stress: traction and stress

12. 12 October 2004GLG310 Structural Geology 35 Faults and stress: traction and stress

13. 12 October 2004GLG310 Structural Geology Faults and stress: traction and stress  =  s -Davis and Reynolds

14. 12 October 2004GLG310 Structural Geology -Engelder, 1993, Stress regimes in the lithosphere, Princeton Univ. Press

15. 12 October 2004GLG310 Structural Geology Faults and stress: traction and stress Coulomb Law of Failure Coulomb equation  c = c + tan   n Where  c = critical shear stress required for faulting (shear strength) c = cohesive strength tan  = coeffieicnet of internal friction = 

16. 12 October 2004GLG310 Structural Geology

17. 12 October 2004GLG310 Structural Geology Faults and stress: traction and stress

18. 12 October 2004GLG310 Structural Geology -D+R

19. 12 October 2004GLG310 Structural Geology

20. 12 October 2004GLG310 Structural Geology