Volcanoes - is geological formation on the surface of the Earth's crust.The volcanoes of the central type are went.Forms of the central volcanoes depend on the composition and viscosity of the magma.The main areas of volcanic activity - South America, Central America.Mud volcanoes - small volcanoes on the surface through which magma is not as liquid mud.Mud volcanoes are much smaller in size than the ordinary.Volcanoes are not only on Earth but on other planets and their moons . The highest mountain in the solar system is a Martian volcano Olympus height of 26 kilometers.In our solar system, the greatest volcanic activity has a Jovian satellite Io. On some planets, satellites in low temperatures spewing " magma " is not composed of molten rock , and out of the water and light materials .
