Sophie Walter - How are volcanoes formed

Geography

How are volcanoes formed?

What is a volcano ?

A volcano is a mountain that opens at the top. On the very bottom of the volcano there is

molten rock, magma. When pressure builds up the volcano can explode so that gasses

and rocks shoot out of the volcano and up into air and the magma flows.

How are volcanos formed ?

Volcanoes are formed when magma forms within the Earth's upper mantle and works its

way to the surface. At the surface, it erupts to form lava flows down the volcano and ash

deposits. When the lava hardens on top of the volcano it adds another layer. Over time as

the volcano continues to erupt, it will get bigger and bigger.

Most volcanoes are formed by the movement of tectonic plates. These tectonic

plates basically float on top of the earth's mantle. The earth's mantle is sort-of liquid rock.

The tectonic plates are constantly moving we don't feel them moving but sometimes we

do. Like when an earthquake occurs we definitely feel them. They can move away from

each other which is called divergent.

They can move into each other which is called

convergent or they can scrape against each other, called transformant. Subduction is when

one plate goes under the other. When a tectonic plate sinks it sinks down to the mantle

which is very hot, so hot that the rock melts. This molten rock will eventually make its way

back up through a series of cracks. When it has reached the top of the surface we call it

lava, after layer and layer of lava forms up, a volcano is formed. In other words when in

subduction one plate slips under the other and the plate has no where to go so the magma

burns the plate and pushes it up.

This is where the hot spot happens, when the magma

breaks through the plate cause it has no other option. Some volcanoes even form

underground and over time they became bigger and bigger due to the magma hardening

quickly by the cool sea water then eventually sweep over sea level and just keep growing.

When the volcano erodes it can be surrounded by coral which circles the volcano forming

a reef. The volcano then cools over thousands of years and sinks and its summits erode.

After this happened the volcano disappears and a lagoon forms in its place.