Liquid Dirt

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Earth Science: Soil Liquefaction
Grade Range: Elementary School, Middle School
Format: Hands-on

This demonstration is easy to set up and easy to run. Be sure to spread the sand out on a tarp after the show to let it dry.

Contents

Materials

  • Small Plastic Tub
  • Sand or Soil
  • Water
  • Small Toys or Objects

Safety Precautions

Please read the General Safety section of the Demonstration Safety page before performing this demonstration.

Demonstration

  1. Set up the demonstration: Fill the bin three quarters of the way with sand or soil, and add enough water to thoroughly wet it, but not so much that there are visible puddles of water on top. Place the objects on top of it.
  2. When students come up, ask them to think of what might happen if the box were to be shaken. After getting responses, gently shake the box side to side, and watch as the objects start to sink right into the ground! Be sure to pull the objects out of the ground and stand them up again after each run.

Why This Works

Liquefaction is what happens when waterlogged soil is disturbed, either by an earthquake or other vibrations. Quicksand is a great example of liquefaction, since it appears to be solid until you start to step on it. then, because of the pressure on the sand due to your steps, the sand particles try to push together around the water that is mixed in. This causes the sand to separate, making where you step more water than sand, and causes you to start sinking. Liquefaction can also happen when low lying, wet areas have an earthquake. When the ground starts to shake, the weight from the objects on top of the soil start to press the ground unevenly. If the ground has a lot of water in it, then the soil particles will slide closer together, like with the quicksand, and can cause buildings and roads to start sinking into the ground!

Additional Information

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