To begin with – what is a volcano? You will probably think of a huge hill filled with lava. Yes, that’s partly true. However, when lava is below the surface it’s called magma and as not all volcanoes have to be large mountains. Volcano is a vent or chimney that connects magma from within the Earth’s lower crust to the Earth’s surface.
Lava is about 700 to 1200°C (that’s something between 1300 to 2200°F) hot semi-solid like substance. When molten lava comes in contact with cold air it becomes a solid rock. Magma contains gases, so there is a lot of pressure. Once magma is close to the surface, these gases expand in the process termed as magma degassing and hence magma explodes and rocks are thrown away from the volcano. Thanks to this, we can find those beautiful volcanic stones full of trapped bubbles.
Watch video from mad_geologist again… here.
