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Although they are often a destructive force, volcanoes are an amazing facet of creation. Volcanoes erupt when magma, red-hot liquid rock, seeps up through a vent in the earth. These vents can be at the top of a mountain or on a flat area. Volcanoes can even erupt underwater if there is a vent in the ocean floor. Magma is formed when part of the earth's mantle gets hot enough to melt. Violent eruptions can occur when pyroclastic material—a mixture of magma, rocks, ash, and hot gases—explodes upward by pressure caused by underground gases and magma.
There are over 1,500 volcanoes around the world today that are considered active, meaning it can erupt at any time. A dormant volcano (like the one in Yellowstone National Park) may become active again, but not for many hundreds or even thousands of years. An extinct volcano no longer has a lava supply and is very unlikely to ever erupt again.
You can create an erupting volcano using wax, sand, and water!
Safety Note: Only use a high-quality glass beaker or liquid measuring cup (such as Pyrex) for this experiment! An ordinary glass jar or drinking glass will likely crack under this amount of heat. Never put a glass container directly onto the stovetop!
Volcanoes erupt when red-hot magma seeps up through a vent in the earth's crust. In this experiment, the wax represents magma from the earth's mantle, and the sand represents the earth's crust. The water is where the crust and the air meet. Once a volcano has broken through the earth's crust lava can flow all over the earth, or it can even be forced out into an ocean. When the wax "magma" reaches the water, it becomes "lava." Just as the wax hardened once it reached the water in this experiment, real lava cools and hardens once it reaches earth's surface.
If you want to see the volcanic reaction again, melt a few drops of wax to stick the used wax to the bottom of a clean beaker. Cover with sand and water, then heat slowly as before. The kind of reaction you will get depends on the levels of sand and wax, as well as how slowly or quickly the alcohol lamp melts the wax. Try to keep the heat as steady as you can for a more dramatic result.