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

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


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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

Anderson's model or theory asperity brittle deformation cataclasis cataclastic flow
cataclastic shear zone coefficient of friction ductile shear zone elasticity failure stress
fault fracture free surface frictional regime frictional sliding
hydrostatic pressure joint lithostatic stress mode I crack mode II crack
mode III crack normal stress opening-mode crack permeability pore pressure
reversibility shear failure shear fracture shear rupture shear stress
shearing-mode cracks tensile crack vein -- --

Some submitted questions related to this chapter

  1. What happens when stress is reduced from an elastically strained material?
  2. Name one example from every-day experience that involves brittle deformation.
  3. What is the difference between a vein and a dike?
  4. What causes hydraulic fracturing?
  5. What effects might increasing pore pressure have on the likelihood that slip might occur along a fault?
  6. What is a brittle fault, as contrasted with a ductile shear zone?
  7. What is the approximate depth range in which you might expect brittle deformation to occur?
  8. What deformation mechanisms are considered to be part of brittle deformation?
  9. What is one characteristic of a Griffith crack?
  10. Compare the confining pressure associated with a fault surface that develops at a small angle to the greatest principal stress (s1) with the confining pressure for a fault developed at a larger angle to s1.
  11. Which is more likely to have brittle deformation: the deep mantle or the shallow crust? Why?
  12. When a structural geologist refers to "the happy angle," about how many degrees is the happy angle supposed to be?
  13. Given the orientation of s1 and s3, how would you draw an opening-mode crack.
  14. Given a simple drawing of an opening-mode crack, label the crack tips and crack faces.
  15. Describe an important attribute of the Coulomb fracture criterion
  16. Describe an important attribute of the Mohr-Coulomb fracture criterion
  17. Describe an important attribute of the von Mises fracture criterion

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