Inside Earth Chapter 3.1 Pages 88-92 Inside Earth Chapter 3.1 Pages 88-92 Volcanoes & Plate...
-
Upload
austen-wilkinson -
Category
Documents
-
view
218 -
download
1
Transcript of Inside Earth Chapter 3.1 Pages 88-92 Inside Earth Chapter 3.1 Pages 88-92 Volcanoes & Plate...
Inside Earth Chapter 3.1Pages 88-92
Inside Earth Chapter 3.1Pages 88-92
Volcanoes & Volcanoes & Plate Tectonics Plate Tectonics
What is a Volcano?
• A weak spot in the crust where molten material, or magma comes to the surface– Volcanic Activity is a constructive force that adds
new rock to existing land or forms new islands.
Magma / Lava
• Magma: melted rock, gases and water vapor from the mantle. Below the surface
• Lava: magma that reaches the surface– Cools and forms solid
rock.Volcano
Menu
Why does Magma Rise?
• Magma is a liquid, so it is less dense than the solid material around it– Flows upward into cracks
in the rocks above– Rises until it reaches the
surface or becomes trapped beneath layers or rocks.
Volcano Menu
Volcano Erupts
• Dissolved gases trapped in magma are under tremendous pressure
• Eruption occurs when the gasses rush to the surface, carrying magma with them.
Volcano Menu
Crater
• Lava collects in the Crater: the bowl-shaped area that forms around the volcano’s vent.
Volcano Menu
Pipe
• A narrow, almost vertical crack in the crust through which magma rises to the surface.
Volcano Menu
Magma Chamber
• A large underground pocket of magma that is made from magma rising to the surface.
Volcano Menu
Divergent Boundaries
• Form along the mid-ocean ridge– Lava pours out of the
cracks in the ocean floor• Iceland is a volcano on
the mid-ocean ridge that has reached the surface.
Convergent Boundaries
• Plates collide– Denser plate subducts towards the mantle.• Forms a deep-ocean trench• The crust melts and forms magma that rises• Rising magma erupts through a volcano on the surface.
Convergent Boundaries
• Ocean/Ocean– Denser ocean plate subducts• Forms a deep sea trench• Forms an island arc of
volcanoes– Japan–New Zealand–Aleutians
Convergent Boundaries
• Continent to Ocean– Dense ocean plate
subducts• Forms a deep sea trench• Forms volcanoes on the
land–Mt. St Helens–Andes Mountains in
S. America
Stages of a Volcano
• Active:– A live volcano that is erupting or shows signs that
it may erupt in the future• Dormant:– A sleeping volcano. It may awake in the future
and become Active• Extinct:– A dead volcano. It is unlikely to erupt again.
Location of Volcanoes
• Most occur along diverging boundaries such as the Mid-Ocean Ridge or in subduction zones.
Location of Volcanoes• About 600 active volcanoes on land, more lie
beneath the sea.– Ring of Fire formed by the many volcanoes that
rim the Pacific Ocean.
Hot Spot Volcanoes• An area where magma from deep
within the mantle melts through the crust like a blow torch
• Lie in the middle of plates– Yellowstone formed under the continent
• The plate travels over the hot spot– Created a chain of islands to form
Hawaii
What to Work On
• Read pages 88-92 in the textbookAnswer the Section 3.1 Review questions
on page 91 (#’s 1-4)
DUE: Friday, November 4th