Geometric and Kinematic Analysis in a Sandbox

Kimberly Hannula
,
Fort Lewis College
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Summary

Introduction to the concepts of geometric and kinematic analysis, using an easily assembled sandbox. Students repeat experiments to see variation. The lab also reviews structural map symbols, and involves some beginning thinking about scale in structural geology.

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Context

Audience

Undergraduate required course in structural geology.

Skills and concepts that students must have mastered

Math: college algebra level; comfort using a calculator with scientific notation.

Concept of strike and dip.

Concept of a structural cross-section.

How the activity is situated in the course

First lab of the semester for structural geology. This structural geology course has a pre-requisite of a sophomore field course, so students have had some experience making geologic maps and cross-sections.

Goals

Content/concepts goals for this activity

Geometric versus kinematic thinking about structures; analogue modeling as a technique for studying structural geology.

Higher order thinking skills goals for this activity

Comparison of experimental results with reality.

Other skills goals for this activity

3D spatial thinking about surfaces; first introduction to penetrative thinking problems.

Sketching as an observational tool and as a tool for thinking spatially.

Description of the activity/assignment

In this lab, students work in groups with a simple sandbox (metal sheets clamped to an adjustable workbench) to create thrust faults, strike-slip faults, or restraining and releasing bends on strike-slip faults. The sandboxes are designed without colored sand layers or vertical sides; they they show surface deformation rather than cross-sections, but also allow students to re-set the models and run them several times with either the same or different conditions. The models are recorded and shared with the class. Students make geometric models (sketches of the surface, using structural map symbols), guess possible cross-sections, and use the videos to develop kinematic models (sketches with arrows showing movement, and short descriptions of their kinematic observations). After making their observations, students measure properties of their materials, do scaling calculations, and compare their models with real examples of similar settings on Google Earth.

Determining whether students have met the goals

This lab is graded based on:
- whether students correctly applied geologic map symbols
- whether they completed the scaling calculations
- completion of sketches
- separation of observations from interpretations
- reasonableness of the discussion (is the discussion consistent with the observations)

More information about assessment tools and techniques.

Teaching materials and tips

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Supporting references/URLs

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