You are now beginning to get an idea of what happens during an eruption and I bet you would not like to be too close! We have already learned about the Earth's plates and we know that when the plates move apart they can cause cracks or gaps which releases the hot molten rock to the surface of the Earth. What we saw in the second video was lava. This is what we call the molten rock when it reaches the surface of the Earth. Let's have a look at the diagram below to get a better idea of what the inside of a volcano looks like.
The Earth's crust is coloured brown in the diagram. This is the outer layer of the Earth. We can see a magma chamber coming up through the crust. Magma is the correct name for the hot liquid molten rock that is leaving the mantle and making its way towards the surface of the Earth. The middle of the volcano has a vent and the magma travels up through the vent. The pressure beneath the Earth's crust can cause the magma to explode out the top of the volcano and such an explosion can blow the top off leaving a crater. As soon as the magma reaches the surface it becomes lava and it oozes down the side of the volcano. Eventually the air cools the lava and it hardens. This means the volcano will have another layer added to it once the lava cools. The more eruptions a volcano has the bigger it gets because the lava keeps cooling and adding extra layers of rock.
DID YOU KNOW? Volcanoes that still erupt are called 'active volcanoes'. Volcanoes that have not erupted for several years are called 'dormant volcanoes' which means they are said to be asleep. Volcanoes that are unlikely to ever erupt again are called 'extinct volcanoes'.
Hi
ReplyDeleteI am originally from the Republic of Mauritius; a small island in the indian ocean(off the coast of Madagascar) and my island was formed by eruption of volcanoes in the sea. We still have about 8 volcanoes in a dormant state in the island at present which can wake up at any time; but its very interesting work on your behalf to see your interest in volcanoes. I now know how a volcano forms and what causes it to erupt. It's also amazing to see how the lava flow can grow to form a country as big as surrey discrict and which has a population of about 1.3 million people.
Keep up the Good work.
Nevin (27 years old, Mauritius)
Hi Fiona and class 4
ReplyDeleteWhat a fantastic blog you have made. It is great to see physical geography alive and well in the classroom. I love balance of video clips, teext and diagrams. Very informative.
Gyles Morris
Naturesbase.
Thank you Gyles. 4G have worked very hard and they will be delighted you are following it.
DeleteThanks Nevin for your informative comment. It is hard to believe a volcano made an island that now has so many people living on it! We hope you continue reading our blog :)
ReplyDeletecool i will use these
ReplyDelete