Connor Cronin friction-climbing on a granite of the Southern California Batholith at Joshua Tree National Park, California. Photo by Vince Cronin.

Introductory Structural Geology, the Frictional Regime

This page is under construction!

Refer to Ben van der Pluijm and Steve Marshak, Processes in Structural Geology and Tectonics (psgt.earth.lsa.umich.edu), chapter 3, pages 61-87.

Terms you should work to understand and use properly

Some submitted questions related to this chapter

1. Why is Anderson's model based on the assumption of homogeneous stress?
2. Why is Anderson's model based on the assumption that principal stresses are horizontal and vertical at Earth's surface?
3. Sketch a block diagram whose upper surface coincides with the ground surface, illustrating a reverse fault, the orientation of the principal stress axes, and labels those axes in a manner consistent with Anderson's model.
4. Sketch a block diagram whose upper surface coincides with the ground surface, illustrating a normal fault, the orientation of the principal stress axes, and labels those axes in a manner consistent with Anderson's model.
5. Sketch a block diagram whose upper surface coincides with the ground surface, illustrating a right-lateral strike-slip fault, the orientation of the principal stress axes, and labels those axes in a manner consistent with Anderson's model.
6. Shear rupturing of previously intact body of rock, and shear reactivation of a previously formed weak surface, are two ways to create ___
7. Is brittle deformation considered to be recoverable or non-recoverable?
8. Is purely elastic deformation considered to be recoverable or non-recoverable?
9. The relationship between volume change and stress is known as ___.
10. How does elasticity apply to rock deformation?
11. What are the two ways to create a brittle fault?
12. What is the difference between shear fractures and tensile cracks?
13. List the different categories of brittle deformation.
14. What are the differences between Mode I, Mode II, and Mode III cracks?
15. When pore fluid pressure is increased, which direction does the Mohr circle move?
16. Why can σ₁ not equal σ₂ for faulting to occur?
17. If a rock deforms in a brittle manner as a result of a stress state in which σ₁ is not equal to σ₂, what sort of deformation would be expected?
18. What are some characteristics of elastic behavior?
19. What are the units associated with the elasticity constant?
20. Positive dilatancy increases __(what)__.
21. What describes the stress state at which a shear rupture forms and separates a sample into two pieces?
22. What represents a response of rock to shear stress?
23. Which catagory of brittle deformation involves the propagation of cracks into previously unfractured material when a rock is subjected to tensile stress?
24. What is the difference between shear rupturing and shear reactivation?
25. At the atomic level, what happens that results in brittle deformation rather than ductile deformation?
26. What is Poisson's ratio used for?
27. Shear stress is a function of __(what)__.
28. Can rock withstand high elastic strain before it is permanently deformed?

If you have any questions or comments about this site or its contents, drop an email to the humble webmaster.
All of the original content of this website is © 2018 by Vincent S. Cronin