VOLCANOES OUR CHANGING EARTH
VOLCANOES VOLCANOES FORM WHEN MAGMA ERUPTS ONTO THE SURFACE THIS OCCURS ALONG PLATE BOUNDARIES MAGMA IN A CHAMBER CAN SIT THERE FOR MONTHS OR YEARS!
VESUVIUS
VESUVIUS COMPOSITE VOLCANO FORMS AT BOUNDARY OF CONVERGING PLATES SIT QUIET FOR VERY LONG TIME, THEN EXPLODE VIOLENTLY
Composite Volcanoes
Composite Volcanoes
MEXICO
CINDERCONE VOLCANO ERUPTS SUDDENLY SPREAD OVER GREAT DISTANCE AND RISES UPWARD
Cinder Cone Volcano
Cinder Cone Volcano Paricutin in Mexico
HAWAII
SHIELD VOLCANOES HAWAIIN VOLCANOES FORM OVER HOT SPOTS IN THE MANTLE. LOTS OF LAVA FLOWS. LOW IN SILICA AND FORMS A SHIELD.
Shield volcanoes
Shield volcanoes - Hawaii
Magma Type Chemical Composition Temperature (degrees C) Viscosity Gas Content Basaltic 45-55% SiO2; High in Fe, Mg, Ca; Low in K, Na. 1000 - 1200 Low Andesitic 55-65% SiO2; Intermediate Fe, Mg, Ca, Na, K 800-1000 Intermediate Rhyolitic 65-75% SiO2; Low in Fe, Mg, Ca; High in K, Na 650-800 High
Active, Dormant, Extinct ACTIVE – ERUPTING RIGHT NOW DORMANT – SLEEPING, COULD ERUPT BUT NOT EXTINCT – HAS NOT ERUPTED FOR THOUSANDS OF YEARS AND PROBABLY WILL NEVER DO SO AGAIN