Basics of structural geology

From GeoClasses

Contents 1 basic concepts 2 processes of deformation 3 geologic structures 4 case studies

basic concepts

• strike and dip
  • how to measure
• geologic maps
• geologic cross sections
  • more complex cross section

processes of deformation

• stress: force applied to the material
• strain: amount of deformation created
  • see animation
• tensional forces
• compressional forces
• shearing forces
  • tension vs. compression
  • try it out for yourself: "a cheesy analogue"
• brittle vs. ductile behavior
  • try it with sheet of styrofoam: elastic vs brittle behavior
    • Is rock elastic? When you fold a rock layer, then take away the stress, what happens? (Plastic deformation)
  • try it with silly putty: brittle vs ductile behavior
    • When are rocks brittle under tension? Under compression?
    • When are rocks ductile under tension? Under compression?

geologic structures

• faulting
  • see foam demo
  • dip-slip vs. strike-slip
  • normal fault
  • thrust fault (reverse)
  • see fig. 7.7
• folding: see website (try making these with colored foam pieces)
  • anticlines
  • synclines
  • see fig. 7.10
  • plunging folds (see fig. 7.11)
  • domes (see fig. 7.12)
• joints
• fig. 7.15 - tectonic settings

What kind of fault is this? (Photo courtesy of Pomona College)

What kind of fault is this? (Photo courtesy of Cedar Strat)

What is this feature? See it with explanation courtesy of UCSC

What are these features? courtesy of DOE

case studies

• tensional tectonics
• compressional tectonics
• shearing tectonics
• interpreting complex geologic history: see fig. 7.19