Geologic Structures Lab

John Leland
,
Glendale Community College
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Summary

In class activity involving a thought exercise about rock rheology, discussion and drawing of simple brittle and ductile structures, and then reading an article about how the depth of the brittle-ductile transition in the crust can be influenced by the sudden changes in stress. The exercise progresses from simple to complex, uses real data, and focuses tightly on the concept of brittle and ductile behavior of rocks.

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Context

Audience

The exercise is used in a Physical Geology Laboratory course (see course profile) that has Physical Geology lecture as a co- or prerequisite.

Skills and concepts that students must have mastered

Discussion of earthquake focus and epicenter is useful during or before the lab, but otherwise there is very little the students need to bring to the activity. The reading assignment at the end of the activity contains many difficult words. I do not provide a dictionary and instead encourage students to ask questions of me and to look at the figures. We discuss this article together after the students have read through it.

How the activity is situated in the course

This is often the second or third activity in my geology lab. The first activity is typically a tour of the campus and a discussion of the geological history of the area. Student interest in earthquakes is quite high because of our location in southern California, so student learning of these concepts is motivated by their desire to understand why near-time earthquake prediction is still an unattained goal.

Goals

Content/concepts goals for this activity

  • Learn what causes rock to deform or break
  • Learn the names of basic geologic structures
  • Learn how to visualize geologic structures in 3-D
  • Learn about the brittle-ductile transition in the crust

Higher order thinking skills goals for this activity

  • Running a simple thought experiment and systematizing observations into a set of variables that influence rock mechanics.
  • Looking at data and understanding the hypothesis proposed based on the data.

Other skills goals for this activity

None that I can think of.

Description of the activity/assignment

Students learn about the variables governing the brittle and ductile behavior of rocks, the simple geological structures associated with differential stress, and look at and apply real data to evaluate the depth to the brittle-ductile transition in the crust and how that depth can change temporarily due to sudden changes in stress introduced by large earthquakes.

Determining whether students have met the goals

Questions asked of me in class during the activity and their own record of their answers to the questions on the activity provide the feedback as well as future use of these concepts in later activities.

More information about assessment tools and techniques.

Teaching materials and tips

Other Materials

Supporting references/URLs