How Differentiated Layers of Sand Are Affected by Lateral Compression

Overview

Objectives/Goals The purpose of my project is to determine the affects of lateral compression on differentiated layers of sand. Since I live in Humboldt County, where plate tectonics and crustal folding play a major role in our geology, I wanted to test what would happen to the Earth's crust when it begins to fold from these stresses and pressures. My hypothesis for Trial 1 (1 1/2 cm sand layers) was that I would get anticline folds. Trial 2 (3 cm sand layers) hypothesis was that I would get monocline folds. My final hypothesis for Trial 3 (1 1/2 cm saturated sand layers) was that I would receive divergent results, as in overthrust folds. Methods/Materials First, I constructed my sand box, using plywood and Plexiglas. Then, for each trial, I filled the box with the designated amount/variable of sand (1 1/2 cm sand layers, 3 cm layers, and 1 1/2 cm saturated layers). I used a drill to move the piston which compressed the sand in the box. I kept the drill at a steady pace. I stopped my piston every 1/4 of the way across the box. I took notes and pictures of the folds that were formed in the sand. The materials I used were: 3/8 in. plywood, 5/16 in. 3 ft. long threaded rod, expansion bolt, acorn cap, 24 x 9 in. piece of Plexiglas, two 25 lb. bags of play sand, food coloring, oven, screws, nails, drill, hammer, screwdriver, wrench, adhesive spray, wood glue, measuring cups, table saw, mitre saw, and a jig saw. Results I charted the results from all three of my variables, in which I compared the top and bottom folds from each trial. After analyzing all of the data, I realized that lateral compression does not have a large affect on sand layers. Even though my results varied from each trial, they all basically gave me anticline folds; however the patterns of syncline, moncline, asymmetrical, overthrust, and recumbant folds were also present in my project. I believe I got the overall result of anticline folds because the angle that the piston was applying pressure automatically pushed the sand upward. Conclusions/Discussion My hypothesis was only accurate for the first trial, Trial 1 (with 1 1/2 cm layers). My hypothesis for the other two trials proved to be incorrect. After completing this project, I now understand many of the variables involved in crustal folding and plate tectonics. I believe that geologists will/should continue their studies in this field, in order to build appropriate structures to help keep people safe.

Awards (1)

• Honorable Mention

Competition history

• CSEF 2012 Earth & Planetary Sciences · Entry J0812

Resources

• CSEF project summary ↗

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