Wednesday, June 30, 2010

Volcano Report

How does a volcano erupt ?

Underneath the earths crust the pressure of the magma builds up. It then is forced up and it makes a vent in the earths surface. After it has erupted the lava then dries up and forms a mountain .

About volcanoes .

Volcanoes are mountains that erupt. It is a vent in the earths crust through which magma and gasses erupt. The word volcano comes from the god of fire, Vulcan. Volcanoes are all over the world. Most volcanoes are on the edge of the tectonic plates .

3 different typ of volcanoes

The shield volcano got its name because people thought it looked like the shape of an ancient warriors shield. The shield volcano is low in silica. They are shallow sided and have a flat bottomed crater. It has a long fluid lava flow which can also flow into sea. Shield volcanoes can also be found on the ocean crust.

The stratovolcanoes are the most famous volcanoes. Mount St. Helens, Mt Vesuvius and Mt Fuji are all stratovolcanoes. When they start to erupt it begins with an explosion of ash and cinders. These volcanoes are often found on subduction zones.

Cinder cone volcanoes are the smallest volcanoes.
These volcanoes are formed by low silica magma that is runny. They are steep sided volcanoes that are cone shaped.

What is the biggest volcano in Auckland ?

The biggest volcano in Auckland is Rangitoto . Rangitoto is one of the youngest volcanoes
but this volcano has the most violent eruption when it occured it last eupted 600 years ago to 800 years . Rangitoto was named after a woman whose name is Te RangiTotongia
that's how it was named Rangitoto .

1 comment:

  1. Hey Helen,

    I never knew that Rangitoto was named after a lady. WOW!! That was a shock. You must of had a lot of research done.