Kind: captions
Language: en
you probably have a pretty good idea
what this is It's a volcano a place
where molten rock called magma from deep
within the earth makes its way up and
erupts at the surface but what you may
not know is that not all volcanoes are
made in exactly the same way in fact
they come in a variety of different
shapes and sizes here are the three main
types of
volcanoes the smallest type of volcano
is the cinder cone Cinder cones form
when thin or runny magma is flung in the
air during an eruption and then hardens
and falls back to Earth in fragments
called Cinders over time these Cinders
build up creating a con shaped Mound
Cinder cones can form rapidly and are
the shortest lived volcanoes a famous
one is the paricutin volcano which
formed in a Mexican corn field in
1943 it was for only 9 years but in that
time it transformed what was once
Farmland into a 1200t high peak
destroying two villages in the
process the largest type of volcano is
the shield volcano these volcanoes pour
out very runny lava flows which can
travel many miles when the flows cool
they form thin sheets these sheets build
up to form a wide Dome that resembles A
Warrior's Shield despite their size
they're actually the G IST volcanoes in
fact tourists can actually watch the
slow flow of lava from the shield
volcanoes that form the Hawaiian
Islands the most common type of volcano
is the composite or Strat volcano these
are what most people think of when they
imagine volcanoes they usually come in
groups of volcanoes all aligned in a
chain they're formed from alternating
lava flows and layers of hardened
particles called tefra that are flung
out of the volcano during an eruption
composite volcanoes have the most
violent eruptions because the lava they
eject is stickier or more viscous than
the lava from Cinder cones or shield
volcanoes as a result more pressure
builds up in the volcano before an
eruption some composite volcanoes have
what's known as a lava Dome at the top
often within the volcanic crater these
form when thick very viscous lava gets
pushed up over the vent like toothpaste
and hardens creating a sort of lid on
the volcano volcanoes with lavadom have
very forceful eruptions because the
magma has to push its way through the
lid Mount St Helens famously grew a lava
dome in the crater that formed during
the 1980 eruption these are the three
main types of volcanoes but there's
plenty more explosive science to
discover
[Applause]