North-Central Section - 39th Annual Meeting (May 19–20, 2005)

Paper No. 1
Presentation Time: 9:00 AM

RED BEANS AND RICE: A SIMPLE LAB EXPERIMENT TO INVESTIGATE SLOPE STABILITY AND LANDSCAPE EVOLUTION IN THE CAJUN LAB!


HICKSON, Thomas A., Department of Geology, Univ of St. Thomas, 2115 Summit Avenue, St. Paul, MN 55105, tahickson@stthomas.edu

In the quest for a quality, hands-on lab experience on slope stability (in the face of numerous, sterile, engineering-based approaches), I stumbled upon an article that appeared in Science (Densmore et al, 1997). The authors constructed a simple acrylic box with a sliding door, filled the box with red beans, lowered the sliding door in increments, and measured the amount of beans that failed with each incremental drop. I adapted this experiment into my “Cajun Lab: Red Beans, Rice and Slope Stability.” In this exercise, students simulate the failure of fractured sedimentary rock (red beans) as a river undermines the toe of a slope (the dropping door). Some students use red beans, others use white rice, in an effort to investigate the behavior of different materials. Initially, I ask students to speculate on the behavior of the experiment, thereby generating a hypothesis. They then run the experiment to determine the behavior of the experimental ‘slope.' Finally, they are asked to submit a lab write-up where they describe their results and critically evaluate the experiment. This lab is followed by a group discussion assignment centered on the Science article and a field trip to a local ravine where many of the processes illuminated by the experiment can be seen in the real world. The lab is very hands-on, students collect data and generate time-series plots of slope behavior in Excel, and they immediately make the connection between slope-forming processes and long-term landscape evolution. I have also tailored the lab to serve as a demonstration in a large (100+ students) introductory geology lecture course and it is sufficiently simple that it could be modified easily for a younger audience. Sometimes, I even start the lab with a bit of Hank Williams' version of “Jambalaya.”