Sand-box experiment to investigate incremental and finite strain
Summary
100 level students, in groups of 3-6, are provided with small sand-boxes fitted with a single moving end. Each box is filled with different colored layers of sand, grit, and ploymer grains to simulate bedding. Students progressivley shorten the layered section and record various parameters at each stage. Students then plot this data graphically and report back on the evolution of the structure (usually a fold), including it's geometry, scale, orientation, etc. This exercise is designed to encourage patient, careful analogue experimentation and data-recording; a successful exercise is assessed by detailed records and integration of different parameters towards a narrative of the deformation.
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Context
Audience
introductory physical geology course for non-majors - could be used in a structural geology class
Skills and concepts that students must have mastered
basics of layering in sedimentary rocks; plate tectonics
How the activity is situated in the course
as a stand-alone exercise
Goals
Content/concepts goals for this activity
patient and careful experimentation
following instructions
patient and careful measurement and data-recording
increment and finite strain
fold geometry and orientation
following instructions
patient and careful measurement and data-recording
increment and finite strain
fold geometry and orientation
Higher order thinking skills goals for this activity
Successful completion requires students to collect data from multiple parameters (not always related intuitively) and relate them. Data analysis in tables, simple arithmetic, and graphs allows for synthesis of data and reporting of conclusions. Students are encouraged to write a narrative of the deformation event and suggest tectonic regimes that might be similar.
Other skills goals for this activity
working in groups
patient and careful analog experimentation - haste will lead to poor data gathering and recording
use of MS Excel for plotting data graphically (required)
patient and careful analog experimentation - haste will lead to poor data gathering and recording
use of MS Excel for plotting data graphically (required)
Description and Teaching Materials
sand-box set-up (a 2448 by 3264 pixel WebP)
experiment in progress (a 2448 by 3264 pixel WebP)
conclusion of the experiment (a 2448 by 3264 pixel WebP)
close-up of the final stage (a 2448 by 3264 pixel WebP)
experiment in progress (a 2448 by 3264 pixel WebP)
conclusion of the experiment (a 2448 by 3264 pixel WebP)
close-up of the final stage (a 2448 by 3264 pixel WebP)
Teaching Notes and Tips
Having access to the sand-boxes is (obviously) key. I used existing sand-boxes (unused for years previously) but each could be made relatively easily for $25-50 each, depending on access to wood-working equipment and expertise.
Set-up is rather laborious but clean-up very easy.
Students MUST be encouraged to be careful and patient while conducting the experiment - if they disrupt the layering (e.g. by dropping or shaking the sand-box) the experiment is compromised.
Set-up is rather laborious but clean-up very easy.
Students MUST be encouraged to be careful and patient while conducting the experiment - if they disrupt the layering (e.g. by dropping or shaking the sand-box) the experiment is compromised.
Assessment
a successful exercise is assessed by detailed recording and integration of different parameters towards a narrative of the deformation
semi-quantitative results are expected; quantitative data encouraged
semi-quantitative results are expected; quantitative data encouraged