Post on 11-May-2015
transcript
Ch. 3 Ch. 3 Sec. 1 Volcanoes & Sec. 1 Volcanoes &
Plate TectonicsPlate Tectonics
• weak spot in crust where molten material comes to surface
http://www.youtube.com/user/NyeTunes#p/u/89/HUCBf058hoA
magmamagma•molten rock from mantle beneath Earth's surface
lava• magma that
reaches surface
http://www.youtube.com/watch?v=K9iZd6wzlCk&feature=related
pillow lava
lava entering the ocean
buried road in Hawaii
After lava has cooled, it After lava has cooled, it forms solid rock.forms solid rock.
• Although you might not wish to touch lava with a "ten foot pole“, this potentially hazardous activity is all in a day's work for a volcanologist.
• The long pole contains a special probe that can measure the temperature of the lava.
Ring of FireRing of Fire
• major volcanic belt formed by many volcanoes that rim Pacific Ocean
Volcanic belts form along the boundaries of Earth’s plates.
Ring of fire
most volcanoes
occur:
alongdiverging
plateboundaries
along converging
plateboundaries
mid-ocean ridge
in subduction
zones
volcanoes at converging volcanoes at converging boundariesboundaries
subduction causes oceanic crust to sink through a deep-ocean trench into mantle
crust melts & forms magma
magma rises back to surface
forms volcanoes
Volcanoes often form where two oceanic plates collide or where an oceanic plate collides with a continental plate. In both situations, an oceanic plate sinks through a trench. Rock above the
plate melts to form magma, which then erupts to the surface as lava.
island arcisland arc• string of islands created by
volcanoes• examples:
Japan
New Zealand
Caribbean islands
Phillipines
hot spothot spot• area where magma from deep area where magma from deep
within mantle rises & melts within mantle rises & melts thru. crust thru. crust
• can occur:can occur:– in middle of platesin middle of plates– on or near plate boundarieson or near plate boundaries– under continentsunder continents
• eg:eg:– HawaiiHawaii– Yellowstone National ParkYellowstone National Park
Hot Spot Volcanoes• A volcano forms above a hot spot when
magma erupts through the crust and reaches the surface.
The Hawaiian Islands formed one by one over millions of years as the Pacific plate drifted over a hot spot.