Reading Guide 10 -- Structual Geology

This is a short but intense chapter. Structural Geology is important for many reasons, for example, the orientation of rocks can tell us about the deformational history or a region, and the structure of strata can trap oil and natural gas.

How are rocks deformed? (pp 409-414)

What is the difference between stress and strain? Check out the stress-strain diagrams. What is the difference between elastic, ductile, and brittle deformation? On fig 14.6, note that the different lines refer to either temperature or strain rate. On fig 14.7, what is the difference between the lithosphere and asthenosphere?

Evidence for Former Deformation (pp 416-426)

Read this section carefully. Make sure you understand a strike and dip and how these two numbers can describe the orientation of any plane in three dimentions.
What is the difference between a fault and a joint? What are the three kinds of faults, and, importantly, what kind of stresses cause them? Study fig 14.13 intently. Be able to associate the kind of fault with the kind of stress that causes it. For example, compressional stresses cause reverse faults. What kind of stresses cause nomral and strike-slip faults? Note that normal faults displace younger strata over older strata, whereas reverse faults displace oleder strata over younger strata. How would you recognize these types of faults if you had no reliable motion indicators? See fig 14.18 for a special kind of strike-slip fault called a transform fault.
Read page 424 carefully and know how to describe a fold. Stare at fig 14.25 intently. You will be expected to decipher the direction of a plunge of a fold from an airial photograph.