How Do You Build a Composite Volcano?

To build a composite volcano, get a cookie sheet, cardboard box, newspaper, brown paint, glue, tissue, baking soda, vinegar, dish washing liquid, a plastic bottle, modeling clay, red food coloring and glitter. Work on a large surface that is easy to clean.

  1. Prepare the surface

    Put newspapers over the work surface. Flatten the cardboard box, and set it on top of the cookie sheet, cutting the box to fit the sheet's size. Cut a larger opening at the top of the plastic bottle. Cut the opening at an angle to create a better view of the fake lava. Glue the bottle to the center of the cardboard, and let it dry.

  2. Make the lava

    Pour half a cup of vinegar into the bottle, followed by a few drops of dish washing liquid, a dash of glitter and enough red food coloring to turn the mixture bright red. Stir these together.

  3. Mold the clay

    Starting at the base, add molding clay to the cardboard to build the volcano shape around the plastic bottle. The base should be wide, then grow narrow as it gets to the top of the bottle. After the clay dries, paint the volcano brown. Wait for the paint to dry.

  4. Trigger the explosion

    To erupt the volcano, put 3 tablespoons of baking soda in a tissue, and tightly roll the ends together, creating a small ball. Drop the tissue into the volcano's opening to set it off.

Composite volcanoes, also called stratovolcanoes, are the most common type of volcano. These volcanoes appear on landmasses and in oceans around the world. Along with cinder cones and shield volcanoes, they form the three basic types of volcanoes classified by geologists. Stratovolcanoes have different shapes than the other two classes of volcanoes; they are more triangular and have steep sides and hollow inner cores that contain lava and magma.

Composite volcano models, if constructed properly, should look like an upside-down ice cream cone, complete with a hole in the center. Volcano replicas can be left alone to show "dormant" states, or made "active" by pouring a mixture of water and baking soda into the centers, which will then "erupt" as lava.