Download Topic 8 Volcanoes

COPY
VOLCANOES
Mr. Rocco
Structure
change
H
The CRATER is an opening at the
Earth's surface.
 It is also a bowl-shaped
depression at the top of the
volcano where volcanic materials
like, ash, lava, and other pyroclastic
materials are released.

The vent is a passageway in the
volcano in which the magma rises
through to the surface during an
eruption.

COPY
…MORE FEATURES of VOLCANOES
 Sill: magma flow
below(horizontally between..)
layers of volcanic cone
 Dike: magma flow across layers
of volcanic cone
The photograph above shows a dike composed of a dark
band of basaltic rock which cuts across the lighter layers of
gneiss. This dike is located on the west side of the Palisades
Interstate Parkway in New Jersey.
H
H
Composite Volcanoes
 Composite
H
volcanoes,
also called strato
volcanoes, are formed by
alternating layers of lava
and rock fragments.
H
St. Augustine volcano,
Alaska. Composite cone.
H
H
Shield Volcanoes

Shield volcanoes are
huge in size. They are built
by many layers of runny lava
flows. Lava spills out of a
central vent or group of
vents. A broad shaped,
gently sloping cone is
formed.
H
H
Here are 4 of the volcanoes that comprise the big island of
Hawaii. They are Mauna Kea (MK), Mauna Loa (ML), Hualalai (H),
and Kohala (K). The photo was taken from near the summit of
East Maui volcano (EM). These are the largest volcanoes on Earth.
13,796 feet
13,679 FT
Cinder Cones

H
Cinder cones are built
from lava fragments called
cinders. The lava fragments
are ejected from a single
vent and accumulate around
the vent when they fall back
to earth.
Mt SHASTA, CALIFORNIA
14,179 FT
H
H
Lava Plateaus
 Lava
H
plateaus are formed
by the large outpourings of
fluid lava from long narrow
openings in the crust and
builds up layer upon layer
each time it erupts.
A pretty good example will be the
Columbia Plateau in the USA
H
H
Pyroclastic Flows
 Pyroclastic
H
flows are
mixtures of hot gas, ash and
other volcanic rocks traveling
very quickly down the slopes
of volcanoes. They are one
of the most dangerous
hazards posed by volcanoes.
H
H
OUCH……
HOT
STUFF!
Mt. Etna, Sicily
(November 2002)
-- Basaltic
volcanism began
on Mt. Etna in
1999 and has
continued through
2003. The
photograph here is
from a sustained
volcanic eruption
from fractures on
the south flank of
Mt. Etna in
November 2002.
Get me
out of
here!!!
H
Lava Channel -- Lava
erupts from vents on the
northeast rift zone of the
Mauna Loa volcano in
1984 to produce a lava
channel. Note the USGS
volcanologist who
appears as a thin white
vertical line in the center
of the photograph.
H
Mt. Augustine,
Alaska -- A
pyroclastic flow from
the 1996 eruption of
Mt. Augustine in the
Aluetian Islands. The
glowing avalanche
races down the
flanks of the volcano
at hurricane-force
speeds. The
avalanche is partly
disguised by the
more bouyant,
billowing ash cloud
that rises above it.
Effects of Volcanoes