Transcript 1A2 Geography - Learning Hub

1A2 Geography
Objectives:
• To identify three types of volcano.
• To discuss both the positive and
negative effects of volcanic activity.
Homework
• For tomorrow’s class, you must complete
question 1, page 79.
1.
(i) Name ONE example of a volcano.
(ii) With reference to the diagram (pg. 79)
explain how volcanoes occur.
Mid-term Assignment
• Please place your mid-term assignments on your
desk so I can collect them.
• Before the mid-term break, you were told that all
assignments will be collected today.
• Marks will be deducted for late submission:
– 5% Tuesday 23rd.
– 10% Monday 2nd.
– 20% Tuesday 3rd.
Assignments will not be accepted after this date.
Before the mid-term break…
You learned that:
• Earth is divided into layers.
• The outer layer (crust) consists of plates.
• These plates move due to convection currents.
• Plates collide, separate and slide past one
another.
• Plate movement leads to volcanic activity.
How was the Mid-Atlantic Ridge formed?
Three types of volcano
• There are three different kinds of volcano,
each classified according to the rate at which
volcanic eruptions occur.
1. Active.
2. Dormant.
3. Extinct.
Active Volcanoes
• Active volcanoes erupt
on a regular basis.
• Examples include:
Mount Etna, Sicily.
Mount St. Helens, USA.
• (We will be learning
more about Mount St.
Helens during
tomorrow’s class.)
Dormant Volcanoes
• Dormant volcanoes
have not erupted for a
long time, but could
potentially erupt again.
• Examples include:
Mt. Vesuvius, Italy –
you’ve already learned a
little about this in History.
Extinct Volcanoes
• Extinct volcanoes have
not erupted in recorded
history.
• They are unlikely to
erupt again.
• Irish examples include:
Croghan Hill, Co. Offaly.
Positive effects of volcanoes
• In pairs, identify one way in which a region
can benefit from volcanic activity – you have
30 seconds!
Positive effects of volcanoes
• Land Creation: Volcanic activity can lead to
the formation of new land which people can
farm and live on.
• Fertile Soils: Soils created from lava flows are
rich in minerals and are very good for
agriculture. Mt. Vesuvius has produced the
fertile soils of the Campania region of Italy.
• Tourist Sites: People visit areas with famous
volcanoes, e.g. Mount Etna, Sicily.
Positive effects of volcanoes
• Geysers: Magma close
to the surface heats
water under ground.
This leads to the
creation of hot springs
where jets of water are
periodically fired into
the air.
• In Iceland, geysers are
used
to
generate
geothermal energy.
Negative effects of volcanoes
• In pairs, identify one negative effect of
volcanic activity in a region – you have 30
seconds!
Negative effects of volcanoes
• Poisonous Gas: Some gases emitted during
eruptions are toxic, e.g. sulphur dioxide. Gases
can also create acid rain.
• Loss of Life: People can be killed by a volcanic
eruption.
• Damage to Property: Lava burns everything in
its path.
Negative effects of volcanoes
• Lahars: Rivers of mud, called lahars, can be
created if a volcanic eruption occurs on a
snow-capped mountain. Here lava mixes with
snow and flows downhill as intensely hot,
boiling mud. Lahars have the potential to
destroy entire towns and villages. This has
happened in Montserrat in the Caribbean.