Describe and Interpret Images: Folded Strata

During this exercise, students will:

• Develop their observation and interpretation skills
• Apply prior knowledge to a problem
• Connect abstract geological concepts to the real world

One of these exercises might take 5-20 minutes within a lecture. The example described below would work for an introductory lecture on faulting, following a lecture on the laws of original horizontality and superposition.

The instructor will need a slide projector and slides of appropriate images, or an overhead projector and the wherewithal to print the appropriate overheads, or a computer projector.

Show the students the image linked to the thumbnail on the left, the Dent de Morcles from Switzerland. Ask them to sketch it, and then ask a series of questions. For each question, have the student turn to their neighbor and work out an answer. Have the students report their answers before asking the next question. Possible questions for students in entry-level geoscience courses could include:

• Based on what we did last class, how do you explain the lines on the cliff face?
• How would you expect the lines to be oriented according to what we learned last class?
• What kind of topography is Switzerland known for?
• How do you explain the shapes of the strata in the Dent de Morcles?

Doing this exercise regularly will help the students develop their observation and interpretive skills. The instructor could institute a "slide of the week" policy, in which the students interpret a slide dealing with the week's topic on the first day of class for each week.

After doing this exercise for a few weeks, you could then have an image interpretation exercise on the midterm or final. Alternatively, one week the image description could be a pop quiz. Instead of reporting answers verbally, each pair must write their names on a sheet of paper and turn them in. The pop quiz option may be necessary if the students are not taking the exercise (or their reading) seriously.

This kind of activity is described in Reynolds and Peacock (1988) .

Steve Reynolds, a geology professor at Arizona State University, also has a website (more info) , How to Observe Landscapes, that gives photograph of Monument Valley and a link to a "Geologist's Observations', which lists many observations with links to a page with questions and possible explanations.

For the original photo and more Dent De Morcles Information (more info) at USRA's Earth Science Picture of the Day (includes several useful links).

Sources for images:

• The American Geological Institute maintains a growing Image Bank (more info) , divided by category.
• Earth Science Picture of the Day (more info) has a substantial, searchable archive of nice photos.
• Martin Miller, a geology professor at the University of Oregon, has posted an online slide collection (more info)
• Lou Maher, a geology professor at the University of Wisconsin, has collected some interesting aerial views with his Geology by Lightplane (more info) project
• For satellite images, especially of Europe, the ESA is developing a library of them.
• Steve Reynolds, a geology professor at Arizona State University has posted 3-D Visualizations of landscapes.