Initial Publication Date: October 27, 2008

Why Teach with Physical Models?

I have found that physical models and experiments can give students deeper insight into sedimentary processes. This is probably obvious and intuitive to most instructors, particularly when it comes to flume experiments and the formation of bedforms and primary sedimentary structures. However, I have found that broader concepts of sedimentary basin architecture and sequence stratigraphy are extremely difficult to convey in a traditional lecture and lab mode. With new experimental facilities like the Experimental Earthscape Facility ("Jurassic Tank") and a small, desktop delta experiment, I have greatly improved my students' understanding of basin margin processes and the fundamental controls on stratigraphic architecture. Furthermore, I believe that these models provide a very sound linkage between geomorphological processes, the stratigraphic record, and sedimentary basin models, much more so than if I teach without them.

When students have the opportunity to work with an actual experiment, when they can 'tweak' the parameters of an entire sedimentary system and see how it responds, they begin to not only understand how the system works, but they begin to ask deeper questions of that system. If these models are placed in a firm field context students can link their hands-on experiences in a tank or a flume to the geology, thereby making better interpretations.

Using the Desktop Delta in the context of a larger problem

Experimental earthscape image
Think about this: you are trying to get your students to develop some real intuition about sequence stratigraphy and the broad-scale controls on stratigraphic architecture. You may have a project where they are correlating multiple stratigraphic columns across an incised valley fill; you may have them working with seismic lines on a continental margin; you may have them working with measured sections from across the Book Cliffs. The fundamental problem is that it can be very difficult for students to visualize how a sequence boundary or a maximum flooding surface forms; highstand, lowstand, and transgressive systems tracts are fairly abstract, particularly when they are drawn on a chalkboard. The swirl of terminology around sequence stratigraphy is overwhelming in and of itself, particularly to undergraduates, so it becomes very important to provide them with a strong visual image that they can connect to these concepts and the processes embodied in them. Better yet, if they can see how these features form in a realistic physical model, they should develop even deeper intuition and understanding.

In my course, I have a final project that relies heavily on data from an Experimental Earthscape Facility (XES basin or Jurassic Tank) experiment. This tank simulates sedimentary basin filling and produces high quality images of stratal architecture not unlike high resolution seismic lines. The great benefit of the Jurassic Tank data is that we know precisely how the deposit and, hence, the stratal architecture, were produced. We know all of the boundary conditions and how they were changed. This provides a unique opportunity for students and teachers: students can make observations and develop geologically reasonable hypotheses and, unlike in the rock record, teachers can provide them with a 'right answer.' Furthermore, the simplified stratigraphy is complete and relatively easy to grasp, so it is not a very far stretch to link this stratigraphy to real-world depositional settings. For more information, read a complete description of this project or a description of how the XES basin works.

For the students to be able to complete this project effectively, they must have a fairly deep understanding of how XES/Jurassic Tank works, how the experimental stratigraphy was created, and how to link this experimental stratigraphy to real-world processes and depositional products. This is where the desktop delta exercise becomes invaluable.

I run the desktop delta exercise outlined above before I ever hand out the Jurassic Tank project guidelines. I want students to have a solid foundation in creating synthetic stratigraphy in a small, two-dimensional tank, before I have them consider the full, three dimensional data from Jurassic Tank. After completion of this exercise, I hand out the Jurassic Tank project guidelines and I have them read a description of XES/Jurassic Tank from GSA Today (Experimental Stratigraphy). This lays the foundation for a much more successful project.

I have run the XES/Jurassic Tank project twice without using the desktop delta and once with it. My experience was that students grasped the overall goals and intent of the project far more effectively with the desktop delta exercise embedded in it. They also had a much more clear understanding of precisely what kind of data they were using in the project and they struggled much less in making their sequence stratigraphic interpretations.