Volcanoes
A volcano is an opening in earth's surface that erupts sulfurous gases, ash, and lava. It can form at plate boundaries, where plates move apart or together and at hot spots.
There are three main types of volcanoes:
- Sheild
- Cinder Cone
- Composite
The Sheild volcano has a quiet eruption and it is built up of basaltic lava spread in flat layers.
The Cinder Cone volcano is an explosive volcano and it is made up of Tephra. When the tephra falls to the ground it forms a steep sided cinder cone volcano.
The composite volcano can vary between quiet and violent eruotions depending on the amount of trapped gases and how rich in silica the magma is. The lava causes less violent eruptions.
When do volcanoes occur?
-Divergent plate boundries, this is when the plates move apart and form deep riffs which lava flows through.
-Convergent plate boundries, They move together, sumersive plates & they form violent volcanoes.
-Hot spots, It is in the middle of the plate and the hot rock is forced to the crust and it forms the hot spot.
