Our school has a library I could visit any time that was very helpful. Also my mom likes to take me to the Public Library that to was also helpful. The places I looked for things like the Internet was very difficult. Volcanoes are formed by cracks or holes in the ground. As lava cools it hardens.
Crystals form and sink to the bottom of the magma chambers.
This can make a volcano explosive. The effects of an eruption can be felt around the world. Lava is 10 times hotter than the melting point of lead. Some believe it came from the Greek god of fire. They call the Greek god of fire Vulcan.