Today’s Agenda…
 Bellringer:
What are compression, tension, and
shearing? Use your notes on Earth’s plates.
 Quiz
 Notes on Volcanoes
 Homework
Volcanoes
Study Pack #5
Today’s Goals…
I
can explain how different types of volcanoes
form.
 I can describe how a volcanic eruption occurs.
 I can describe the stages of a volcano.
What are volcanoes?
 Weak
spots in the crust where magma comes to
surface, cools, and becomes cone-shaped layers of
rock
Where are volcanoes located?
 600
active volcanoes on land
 Many more beneath the sea
 Volcanoes occur in belts that extend across
continents and oceans
 Ring
of Fire formed by many volcanoes that circle the
Pacific Ocean
Ring Of Fire
Where are volcanoes located?
 Volcanic
belts are found along the plate boundaries
 Mostly
divergent plate boundaries or convergent plate
boundaries where subduction occurs
 Some
 An
volcanoes also occur at hot spots
area where magma melts through the crust
Types of Volcanoes
 Cinder-Cone
 Composite
 Shield
Cinder Cone
 Steep,
cone-shaped hill or mountain
 Lava piles up and hardens
Cinder Cone
Sunset Crater, Arizona
Composite
 Form
at convergent plate boundaries where one
plate is pushed (or subducted) under another plate
 Magma is forced up through many cracks in the
crust
 Sometimes explosive
Composite
Mount St. Helens, Washington
Shield
 Often
form underwater at divergent plate
boundaries
 Can also form over hot spots
 Lead
to the formation of the Hawaiian Islands
Shield
Kilauea, Hawaii
Inside a Volcano
 Page
302
 Magma flows from the magma chamber up the
pipe
 Magma flows out of the vents and becomes lava
 Lava often collects in the crater and then flows
down the slope
 Lava hardens to form rock (igneous rock)
Stages of Volcanoes
– a volcano that is erupting or may erupt in
the future
 Dormant – a volcano that is “sleeping” but may
erupt in the future
 Extinct – a “dead” volcano that is unlikely to erupt
again
 Active
Homework
 Journey
Through a Volcano Writing