Vocanoes are often (but not always) cone shaped,formed by material from the mantle being forced through an opening in the earths cruth,the vent
A composite volcanoe is made up of lava and ash
1) four different substances can be ejected through the vent
- Ash
- gas
- pieces of rock known as volcanic bombs
- molten rock- known as magam when it`s under the ground and lava reaches the surface
2)once this material has been thrown out at the surface,it cools and hardens,forming the volcano mountain from the mixture of ash and lava.
3) Mount Etna is a famous example of a composite volcano
Sheild and cone volcanoes are made of lava only
1) Shield volcanoes: where the lava is basic and runny. it flows quickly and easily spreading over large areas forming wide, flat feature -eg. Manua Loa
2) Cone volcanoes: where the lava is acid and thicker. it flows more slowly and hardens quickly to form steep-sided features - eg. Mount St. Helens
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