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VOLCANOES
The word "volcano" comes from the little island of Vulcano in the
Mediterranean Sea off Sicily (Italy).
Centuries ago, the people living in this area believed that Vulcano was the
chimney of the god Vulcan ( he was the blacksmith of the Roman gods -- he
made things out of metals).
They thought that the hot lava pieces and clouds of dust erupting from Vulcano
came from Vulcan's furnace as he made thunderbolts for Jupiter, king of the
gods, and weapons for Mars, the god of war.
In Polynesia the people attributed eruptive activity to the beautiful but wrathful
Pele, Goddess of Volcanoes, whenever she was angry or spiteful.
Today we know that volcanic eruptions are not super-natural but can be studied
and interpreted by scientists.
So, What is a volcano?
Volcanoes are mountains, but they are very different from other
mountains; volcanoes are built by the accumulation of their own
eruptive products -- lava, bombs (hardened lava blobs), ashflows,
and tephra (airborne ash and dust).
A volcano is most commonly a cone shaped hill or mountain built
around a vent that connects with pockets of molten rock (magma)
below the surface of the Earth.
The term volcano also refers to the opening or vent through which
the molten rock and associated gases are expelled.
What Does a Volcano Look Like?
In your packet, draw what you imagine when you
think of a volcano.
Look at the next few slides.
Decide whether each picture is of a volcano (yes or no).
click to continue…
PICTURE #1
PICTURE #2
PICTURE #3
PICTURE #4
PICTURE #5
PICTURE #6
PICTURE #7
PICTURE #8
How did you do?
If you answered yes to every picture, then you got them ALL
correct!
Every picture was of a volcano … are you surprised?
Many people think that all volcanoes look something like this
TYPES OF VOLCANOES
As you may have already figured out, there are different
types of volcanoes.
The 3 types are:
1. Shield
2. Cinder Cone
3. Composite (or Stratovolcano)
Shield Volcanoes
• A shield volcano is a
large, gently sloped
volcano
• Materials Erupted:
mainly liquid lava, so the
volcano is made of layers
of hardened lava.
– Non-explosive eruptions
• Example: the volcanoes
of Hawaii
Cinder Cone Volcanoes
• A cinder cone volcano is
a relatively small, steeply
sided volcano. These
volcanoes often have a
visible crater.
• Materials Erupted:
small pieces of hardened
lava (rock fragments) called cinders
– Moderately explosive
• Example: Paricutin
(Mexico)
Composite Volcanoes
• A composite volcano is a
huge mountain-like
volcano.
• Materials Erupted:
sometimes lava,
sometimes rock
fragments.
– May have very explosive
eruptions
• Example: Mount St.
Helens
Volcano Types
Look at the following slides.
In your packet identify each volcano as …
*shield
*cinder cone
*composite (stratovolcano)
Picture A
click here to proceed
Picture B
click here to proceed
Picture C
click here to proceed
Picture D
click here to proceed
Picture E
click here to proceed
Picture F
click here to proceed
How did you do?
A = composite (Mount Rainier, WA)
B = shield
C = composite (Popocatepetl, Mexico)
D = cinder cone (Paricutin, Mexico)
E = shield (Mauna Loa, Hawaii)
F = cinder cone (Papua New Guinea)
•Click green button to return to volcano picture
•The green button in the lower left of volcano picture will return
you to this screen
Terms to know …
Caldera - A caldera is a
large, usually circular pit at the
peak of a volcano.
It forms when a volcano erupts
violently.
If enough magma erupts there
is nothing to hold up the
volcano - this leads to the
collapse of the volcano and the
formation of a large pit.
Vent
Vents are openings in the Earth's crust from which molten rock and
volcanic gases escape onto the ground or into the atmosphere.
Vents may consist of a single circular-shaped structure, a large
elongate crack or a tiny ground crack.
VOLCANIC ACTIVITY
Click to continue …
ACTIVE - A volcano that has erupted in the recent
past and is expected to erupt again.
DORMANT - A “sleeping” volcano. A volcano that has
not erupted in the recent past, but could erupt again.
EXTINCT - A volcano that is not expected to erupt
again.
Volcano Research
You will be assigned a volcano to research. Each volcano has
something interesting and unique about it - find out what it is!
For each volcano you will be researching
*where the volcano is located
*when the famous eruption occurred
*what type of volcano it is
*what is unique or interesting about the volcano
*is the volcano active, dormant or extinct
Ask your teacher for a research form and begin! Some helpful
websites are listed on the next slide …
Try these sites to get your
research started
Volcano World
Encarta (type in volcano name)
Smithsonian Volcano Page
Volcanoes Live
Info. on Mount St. Helens
Encyclopedia.com (type in
volcano name)
Info. on Mount Rainier
Volcanoes Listed by Name
Hawaii Volcanoes
U.S. Geological Survey - volcano page