Transcript volcanoes ppt

Volcano
• Weak spot in the crust where magma comes
to the surface
Volcanoes
Form under the ocean at mid-Atlantic ridge or
subduction zones
vpand under the ocean(more than on land)
Magma
– forms inside a volcano
– molten mixture of rock, gases and water from the
mantle
Lava
• magma that forms outside a volcano
• turns into volcanic rock when cooled
Constructive Force
• Volcanic activity is a constructive force
– adds new rock
– adds new crust
Ring of Fire
-abundance of volcanoes that rim the Pacific
Ocean
Island arcs
– Islands formed by a string of volcanoes
– Follows the curve of an ocean trench
•
Ex- Japan, Caribbean, New Zealand,
Aleutian islands(Alaska)
Notice the Arc
Volcanologists –study volcanoes
Hot Spot volcanoes
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Hot spot-area where magma from deep within the mantle melts through the
crust like a blow torch
Often lies in the middle of plates far from boundaries
Gradually forms volcanic mountains
Ex- ocean, Hawaiian islands in the Pacific
Ex- land Yellowstone National Park, Wyoming
http://geology.wwu.edu/dept/fa
culty/hirschd/courses/2012/fall/
101/lectures/media/Lecture04/
HotSpot.swf
https://www.classzone.com/boo
ks/earth_science/terc/content/vi
sualizations/es0904/es0904page
01.cfm?chapter_no=visualization
Hot Spot Volcanoes
• Young volcanic mountains are found closer to
the hot spot
• Older volcanic mountains are found further
away from the hot spot
• Hot spots are found in the MIDDLE of plates
• The hot spots stay still while the plate moves.
• Connection-rock and the mid Atlantic Ridge
Arch Islands
• Found near boundaries
• Found near trenches