Analysis of Sidewalk Fractures

Charles Onasch
,
Bowling Green State University
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Summary

Using fractures in sidewalks as an analog for natural outcrops, students learn to make systematic observations, measure the orientation and location of fractures, manipulate and analyze data, and consider some kinematic and dynamic questions regarding the origin and significance of fractures.

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Context

Audience

This activity is used in a Junior-level course in structural geology, which is a required course in the Geology curriculum.

Skills and concepts that students must have mastered

Students should know how to use Excel.

How the activity is situated in the course

The activity is done as the first lab of the Fall semester. The results of the lab are reintroduced mid-semester when we cover brittle deformation.

Goals

Content/concepts goals for this activity

Students gain experience in making systematic observations on the occurrence of fractures and how the orientation of planar structures is measured. While in the field, students are asked to consider how the fractures formed (what stresses were present and how were they oriented) and how the fractures may have changed the geometry of the sidewalk since it was constructed.

Higher order thinking skills goals for this activity

Students must analyze the data to see if preferred orientations and locations exist. They are asked to speculate on this in the field, then test those hypotheses with their data.

Other skills goals for this activity

Students work in groups so they must learn to collaborate. The field data must be manipulated in Excel to determine is preferred orientations or locations of fractures exist. Finally, the lab is turned-in as a report with figures so writing skills are emphasized.

Description of the activity/assignment

Sidewalks provide a good analog for the study of fractures when outcrops are not available. This exercise is taught as the first lab of the semester in an undergraduate structural geology course. Students learn to make systematic observations, measure the orientation and location of fractures, manipulate and analyze data, and consider some kinematic and dynamic questions regarding the origin and significance of fractures. Their experiences are also used later in the course to reinforce key concepts of brittle deformation. Done as a group project, it emphasizes the importance of group work and encourages students to propose and defend their ideas.

Determining whether students have met the goals

The learning outcomes are assessed by:
1. the quality and quantity of data collected
2. how well the data are manipulated into a useable format
3. how well the data are used to test hypotheses on the origin and significance of the fractures
4. whether the students can make comparisons between sidewalk fractures and natural fractures when we cover brittle deformation later in the course.

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