VOLCANOES

What is it a volcano?

A volcano is like a chimney in the Earth’s crust

(surface) where magma flows out.

Eruption

In 1883, in Indonesia, a volcano called Krakatoa erupted at first.

Krakatoa

The inside of the Earth is very hot, and some of the solid rock melts to form hot, liquid rock called magma.

The hole of the volcano is called vent.

When magma leaves the vent it becomes lava.

The life of a volcano

Inside a volcano

Vent

Hard lava

Magma chamber

Magma

The Earth

The theory called plate tectonics explains

how volcanoes form.

Some volcanoes form above a hot spot, which is

a very hot place in the mantle.

A volcanic eruption

Contents: gas, dust, water vapour, lava and ash

Gas, dust and water vapour

Vent

Lava

Magma

Magma chamber

Layers of lava and ash

Types of volcano

Scientists put volcanoes into three groups:

1. An Active volcano is one that is erupting or will soon erupt.

2. A Dormant volcano is one that has not erupted for a long time.

3. An Extinct volcano is one that has not erupted for more than 10.000 years.

Are in many places in the world, in many

different shapes and sizes.

TYPES OF VOLCANOES:Fissure volcano, Shield volcano, Dome volcano, Ash-cinder volcano, Composite volcano and Caldera volcano.

Volcanic landforms

Rocks and lava

Volcanoes produce lava and rocks we find

on the Earth’s Surface. Magma forms igneous

rocks. These fragments are called tephra.

Bomb Lapilli

Types of tephra

Ash Dust

Liquid lava flows fast and form smooth folds that

look like rope this is called pahoehoe.When slow, sticky lava gets hard, it forms

rocks with sharp edges; it’s called aa.Sometimes lava forms long, thing strings like

human hair this are called Pele’s hair.

Underwater volcanoes

The floor of the ocean is similar to dry land.

There are flat plains, mountain ridges, canyons and trenches in the ocean

floor.There are more volcanoes under the

ocean than on the land.

Living with volcanoes

The minerals and chemicals in the lava and ash make

soil fertile so it’s good for farming.Volcanoes also produce electricity. This electricity is called geothermal energy and the people use it.

VolcanologistsSpecial scientists are called

volcanologists. They study volcanoes in different

ways. This helps to learn about the volcano’s

history and to know what it is going to do.

Volcanologist’s suit

Laura GARRIGA SAGALÉS

Laia GONZÀLEZ TORNER

2on C.C.S.E.P.

CURS: 2008-2009