Home Store Project Ideas Project Guide Ask An Expert Blog Careers Teachers Parents Students

Under Pressure: Sand Under Lateral Compression

Difficulty
Time Required Long (2-4 weeks)
Prerequisites To do this project you should have some experience building things from wood. You will also need access to a reasonably well-equipped wood shop for building the apparatus used in this experiment
Material Availability Readily available
Cost Average ($50 - $100)
Safety Adult supervision required for using power tools

Abstract

Here's a project that involves a different kind of sandbox than the ones you usually think of. This one has a moving wall inside, acting like a piston, to compress the sand. You can make layers using two different colors of sand, and then see what happens when you compress the layers with the piston. If you're handy with woodworking tools, this is a good project to give you a feel for the effects of geological forces that deform the Earth's crust.

Objective

The goal of this project is to investigate how layers of sand deform under lateral compression.

Credits

Andrew Olson, Ph.D., Science Buddies

Sources

This project is based on:

Cite This Page

MLA Style

Science Buddies Staff. "Under Pressure: Sand Under Lateral Compression" Science Buddies. Science Buddies, 10 Jan. 2013. Web. 29 Aug. 2014 <http://www.sciencebuddies.org/science-fair-projects/project_ideas/Geo_p024.shtml>

APA Style

Science Buddies Staff. (2013, January 10). Under Pressure: Sand Under Lateral Compression. Retrieved August 29, 2014 from http://www.sciencebuddies.org/science-fair-projects/project_ideas/Geo_p024.shtml

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.


Last edit date: 2013-01-10

Introduction

If you've studied Earth science in school, you know that the surface of the Earth (the crust) is made up of many separate plates (Figure 1, below). These plates ride on top of the deeper, molten layer of the Earth, the mantle. You also learned that the plates are not stationary, but are slowly moving. What happens to the Earth's crust when tectonic plates collide?

One result of the tremendous forces generated by movement of tectonic plates is the folding of the Earth's crust. For a quick demonstration, grasp a sheet of paper lengthwise with one hand at each end of the paper. Slowly push your hands together. The paper buckles, with the center either rising upward or extending downward as you bring the ends of the paper toward each other. Due to the tremendous pressures that can be created by plate movement, this kind of folding can occur with layers of rock.

Geologists have names to describe the different types of folds. When the layers have just a slight bend, it's called a monocline. When the center of the fold rises up like an arch, the fold is called an anticline. When the center of the fold falls down in a trough, the fold is called a syncline. When the compression forces are very great, you can sometimes see multiple anticlines and synclines following one after the other. There are also more complex folds called recumbent folds ("recumbent" means "lying down"). As you might imagine, these are folds that have been "knocked over" by additional shearing forces. A reference in the Bibliography has example diagrams to illustrate each of the folding patterns described above (Pidwirny, 2007).

It's a little hard to generate enough force to bend rocks with an apparatus that you can easily build in your garage, so for this project you'll be investigating layers made with different colors of sand instead of rock. For your experimental apparatus, you'll build a sandbox with a moveable piston to compress the sand (see Figure 2 in the Experimental Procedure).

To do the experiment, you first carefully load up the box with layers of sand, alternating two different colors to make the layers readily visible. Then you use the piston to apply a compressive force to the layers of sand. Transparent windows in the sides of the box allow you to see the resulting layering patterns after the compressive force has been applied. You can take successive pictures, or record with a video camera, to see how the patterns develop over time as the force is applied.

The surface tension of water causes the grains of sand to stick to one another, so you could investigate the effect of changing the wetness of the sand used. Or, you could investigate the effects of changing the grain size of the sand used. Or, while you're doing the experiment, your own observations may lead to another avenue of exploration. Press on and find out!

map of major tectonic plates of the earth
Figure 1. Map of major tectonic plates of the earth. (Tilling, date unknown).

Terms and Concepts

To do this project, you should do research that enables you to understand the following terms and concepts:

  • Structure of sand
  • Compression
  • Plate tectonics
  • Crustal folding
    • Monocline
    • Syncline
    • Anticline
    • Recumbent fold

Questions

  • Will folding patterns be affected by the grain size of the sand used?
  • Will folding patterns be affected by the wetness of the sand used?

Bibliography

Materials and Equipment

To do this experiment you will need the following materials and equipment:

  • Tools:
    • Table saw, circular saw, or hand saw for cutting plywood
    • Router, sabre saw, or coping saw to make cut-out(s) in sides for viewing
    • Power drill and drill bits (including pilot bit for wood screws)
    • Plexiglass/acrylic scoring tool
    • Straightedge
  • Half sheet (4' × 4') of 3/4" plywood
  • 1/4" or 3/16" thick transparent Plexiglass/Lexan/acrylic material for sides
  • Length of 1/2" threaded rod for applying lateral pressure
  • Mounting hardware for threaded rod
  • Strip of sheet metal (for "scraper" at bottom of piston)
  • Box of #10 wood screws (for assembling sand box)
  • Camera and/or video camera
  • Tripod
  • Sand
    • You'll need some colored sand to make visible layers. You can find this at art/hobby stores or online. One online source is Blick Art Materials.
    • You can experiment with dry sand vs. wet sand.

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.

Experimental Procedure

  1. Use the photograph below as a guide for building the sandbox. The exact dimensions are not critical.

    sand compression apparatus
    Experimental apparatus for compressing layers of sand. (Indiana School for the Deaf, date unknown)

  2. Here are some tips for the construction:
    1. The brace at the right side of the box (yellow arrows) needs to be sturdily mounted.
    2. Naturally, it will be important to make sure that all of the corners are nice and square.
    3. The piston needs to fit snugly against the plastic sides.
    4. Attach a flat strip of sheet metal at the bottom of the front face of the piston. It should be flush with the bottom of the piston. The sheet metal will act as a "scraper" to keep sand from slipping underneath the piston. The photograph below shows how much sand was left behind before the sheet metal strip was installed.

      sand compression apparatus, detail view
      Before a sheet metal "scraper" was installed at the bottom surface of the piston a lot of sand could "leak" under the piston as it moved. (Indiana School for the Deaf, date unknown)

    5. In the design shown, there is a nut mounted inside the brace at the right hand side. The crank is turned, which rotates the threaded rod, and advances it through the nut. The threaded rod pushes the piston to compress the sand. At the piston end, the threaded rod is mounted in a metal bushing, which holds the rod in place but allows it to turn.
  3. For each experiment, you'll need to carefully load the box with sand, alternating layers of different colors. Here are some ideas for you to try (remember to change only one variable at a time):
    1. Vary the wetness of the sand.
    2. Vary the coarseness of the sand.
  4. Advance the piston by turning the threaded rod.
  5. Use a video camera to record the results, or take still photographs at regular intervals.
    1. For photographs, you will probably get better results if you turn the camera's flash off. This will avoid glaring reflections from the Plexiglass windows. If you are shooting indoors, you will probably need a tripod (or other sturdy support for the camera) so that the shot is not blurry.
    2. You may want to take separate photographs showing both side views and top views of the sand (see below):

      sand compression apparatus in action, side view
      Side view of sand compression apparatus in action (Indiana School for the Deaf, date unknown).

      sand compression apparatus in action, top view
      Top view of sand compression apparatus in action (Indiana School for the Deaf, date unknown).

  6. As with any scientific experiment, you should run repeated trials with the same conditions to verify that your results are consistent.
  7. What layering patterns do you see? For example, do you see any examples of:
    1. monoclines?
    2. synclines?
    3. anticlines?
    4. recumbent folds?
  8. What similarities persist across the various experimental conditions you tried?
  9. What differences did you notice?
  10. Advanced. Can you explain how the force of the piston is transmitted through the sand to create the folding patterns in the layers?

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.


Variations

  • Try using sands with various grades of coarseness. You should be able to find different grades at your local hardware or building supply store.
  • What happens if the pressure is applied back-and-forth instead of steadily advancing?
  • If you want to get really fancy, you may even want to consider modifying the apparatus to use a hydraulic drive for the piston. You should be able to better control of the speed of the motion, and you may have the ability to increase the speed of the motion this way. What effect do the dynamics of the motion have on the layers of sand?
  • Note: the following idea has not been tested, so it may or may not work. You might try using layers of more solid materials to see if faulting would occur and what patterns would result. You might try thin layers of plaster, or cement without sand in it. For these harder materials, you would probably need to use two threaded rods to apply sufficient pressure to the piston. A potential drawback of this project idea is that the materials you are testing may prove to be more durable than your box, in which case it will be the box that breaks instead of the test material. You will definitely want to wear safety glasses, in case any bits of material go flying.

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.

Ask an Expert

The Ask an Expert Forum is intended to be a place where students can go to find answers to science questions that they have been unable to find using other resources. If you have specific questions about your science fair project or science fair, our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.

Ask an Expert

Related Links

If you like this project, you might enjoy exploring these related careers:

Geoscientist from Chevron

Geoscientist

Just as a doctor uses tools and techniques, like X-rays and stethoscopes, to look inside the human body, geoscientists explore deep inside a much bigger patient—planet Earth. Geoscientists seek to better understand our planet, and to discover natural resources, like water, minerals, and petroleum oil, which are used in everything from shoes, fabrics, roads, roofs, and lotions to fertilizers, food packaging, ink, and CD's. The work of geoscientists affects everyone and everything. Read more
Mechanical engineer building prototype

Mechanical Engineer

Mechanical engineers are part of your everyday life, designing the spoon you used to eat your breakfast, your breakfast's packaging, the flip-top cap on your toothpaste tube, the zipper on your jacket, the car, bike, or bus you took to school, the chair you sat in, the door handle you grasped and the hinges it opened on, and the ballpoint pen you used to take your test. Virtually every object that you see around you has passed through the hands of a mechanical engineer. Consequently, their skills are in demand to design millions of different products in almost every type of industry. Read more

Looking for more science fun?

Try one of our science activities for quick, anytime science explorations. The perfect thing to liven up a rainy day, school vacation, or moment of boredom.

Find an Activity