word "volcano" originally comes from the island of Vulcano
in the Mediterranean Sea near Sicily. A long time ago, the people
who lived here believed that Vulcano was the chimney of the forge
of Vulcan - the blacksmith of the Roman gods. Volcanoes are mountains
but are not formed in the same way as regular mountains. A simple
explanation of how they are formed is that as magma escapes from
under the Earth's crust it hardens and as more and more builds up
you eventually have a volcano.
There are three main types of volcanoes: scoria
cone, shield volcano, and stratovolcano. Scoria cone volcanoes are
the most common and smallest type of volcano. They are usually less
than 300 meters high. Sunset crater (pictured below) in Flagstaff,
AZ is a classic example of this type of volcano.
Shield volcanoes are very broad and wide. They
can range from only a few kilometers to over 1000 kilometers.
Mauna Loa in Hawaii (pictured below) is a famous example of this
type of volcano.
The stratovolcano is the most obvious type of
volcano and the most deadly. Most stratovolcanoes eruptions are
highly explosive with deadly pyroclastic flows consisting of hot
volcanic fragments and toxic gases. Mt. Fuji in Japan (pictured
below) is a famous example of this type of volcano. View a NASA
flyby animation of Mt.