Academic journal article Journal of Geoscience Education

Watch Faults Grow before Your Very Eyes in a Deformational Sandbox

Academic journal article Journal of Geoscience Education

Watch Faults Grow before Your Very Eyes in a Deformational Sandbox

Article excerpt

ABSTRACT

In this paper, we provide both a step-by-step description of how to build an apparatus for investigating extensional and contractional faulting and we provide lab procedures that teachers at both university and high-school levels can use to enhance students knowledge of the fundamentals of faulting mechanisms. The experiments are based on the analog modeling principle, where large geologic processes (both in terms of time and space) are scaled down to be observed in real time within a classroom. The technique is relatively simple, low-cost and reproducible in a short time span. The experiments offer students both a hands-on experience that is a proxy for more complicated laboratory techniques used by researchers and the opportunity for students to see faults grow before their very eyes. We followed this approach with student groups at different training levels (university and high-school) and found that the experiments boost understanding of the processes of faulting. We highly encourage university level teachers to use this technique both within their own curriculum and within programs that transfer knowledge of geologic concepts to high school teachers and students.

INTRODUCTION

Students that are not yet familiar with the concepts of geologic scales of time and space may find difficult to understand that faults observed in the field are the result of millions of years of continuous interaction between forces in nature (Libarkin et al., 2005). Furthermore, two-dimensional outcrop exposures of faults do not offer students a clear illustration of the fundamentally three-dimensional architecture of faults. Because geologic time and 3D visualization have become central issues within modern geology, students should become acquainted with these challenges in the early stages of training.

We have designed five experimental procedures that can be used with high school students, introductory undergraduate students and upper-level structural feology students. The experiments were initially esigned as part of an outreach program with high school students that integrates sandbox experiments in the labs with direct observation of faults in the field. The deformation apparatus described in these pages has been used for over four years by teachers at five high-schools across the USA (www.geo.umass.edu/structure/cooke / FSE-SO ARhigh/) and has been successfully implemented within upper-level undergraduate structural geology classes at UMass- Amherst as well as other universities. While the experiments presented here are appropriate for high-school students who have been introduced to plate tectonics, more advanced students can use the same experiments to delve into advanced concepts such as force, equilibrium and heterogeneity. The experiments allow detailed investigation of how both normal and thrust faults interact in space and in time (4D) and approximate the first order processes occurring in nature. Sandbox modeling is an excellent tool for boosting understanding of new concepts through laboratory testing as it fulfills four basic requirements:

1. hands-on approach (e.g. Gates, 2001, Lee, 1998)

2. simplicity or the technique

3. constraint of the boundary conditions

4. relevance to geologic processes

Students follow the experimental procedure step-by-step from model design to experiment set-up and become familiar with concepts, such as material properties, reproducibility of results and testing new ideas. They also learn to compare experimental results to observations in nature and learn to develop increasingly more complicated hypotheses (e.g. Csikszentmihalyi, 1996). The students also evaluate the most appropriate boundary conditions for different geologic scenarios, which ultimately enhances their understanding of deep-seated processes in nature.

The sandbox modeling technique has been successfully applied to simulate the deformation of large-scale mountain ranges and basins and has provided critical insight into some of the tectonic Erocesses of mountain building (e. …

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