stereonet lab

(There are programs to use with the computer instead of plotting stereonets by hand, but I find that you have to understand what you're doing to manipulate them in a productive manner.   My answer keys end up being done first by hand, then via a program, but I don't encourage the students to move beyond tracing paper.)

Pre-lab lecture:
  • definition of strike, dip, trend, plunge, and rake
  • quadrant vs. azimuth (including several examples of how to convert from one to the other)
  • European vs. American order for trend & plunge
  • stereonets:
    • 2D method of displaying 3D data
    • demonstration of planes vs. a globe (I use a glass mixing bowl & a piece of cardboard)
    • discussion of projections with reference back to mineralogy & petrology (quaternary diagrams in 2D)
  • setting up the stereonet for use:
    • card stock with thumbtack and tracing paper (discussion about why we use a piece of tape & a spare eraser to keep the thumbtack in place as well as stopping it from stabbing us constantly)
    • tracing the primitive
    • labeling N
    • including name, lab #, and problem # on each sheet of tracing paper
    • using a harder lead (e.g. 2H or 3H) to reduce smudging
How I run the lab:
  • hand-out stereonets, tracing paper, thumbtacks & tape
  • demonstrations of several problems:
    • plotting a plane as a trace (e.g. N20E 32 SE)
    • finding the pole to a plane (use the plane above)
    • plotting a line (e.g. T&P N70W 40)
    • a line pitching within a plane (e.g. N10E 70E, line pitches 40N)
    • rotation of a line
      • vertically (e.g. T&P N70E 35, CW 20)
      • horizontally (e.g. T&P N70E 35, around N20E axis CCW15)
      • inclined (e.g. T&P N70E 35, around N15E 10 axis CW20) 
  • I do one part of the demonstration, then let the students work on several of the related problems from the lab handout (attached below) before moving onto the next portion of the demonstration
Where the problems are originally from: I've run two different versions of this lab.   I've taken the questions that I had to answer back when I took structure from Kim Hannula and usually hand those out first.   If the students struggle with the concepts and it appears we need a 2nd week of stereonet problems, I pull problems either from Marshak & Mitra (1988) or Rowland, Duebendorfer, and Schiefelbein (2007).   I believe even Kim doesn't use these questions anymore, but I simply like them better than the book versions.

last revision: 7. February 2011
Elli Goeke,
Feb 7, 2011, 2:05 PM