Volcanoes The objective of this project is that I am going to explain about volcanoes, the different types of volcanoes and tell some other interesting facts on this subject. Here is some background information about volcanoes. Volcanoes are vents in the Earth where molten rock (magma) and gases erupt. Molten rock inside the Earth is called magma. The source of the magma-producing heat is thought to the decay of radioactive isotopes in the Earth. When magma flows out of the volcano it is called lava. Lava may erupt out of a volcano in many different forms, from large pebbles to dust. There are three main areas where volcanoes are