Ch 12 Volcanos
Igneous Processes
Extrusive Igneous Formations

Volcanoes
 __________ in the Earth that erupt __________, ash, & lava.
 Lava flows __________ everything in their path.
 __________ flows (ash & debris) rush down the __________ of the volcano.
 Acid rain is produced when __________ gases mix with water vapor in the atmosphere.
 Parts of a __________
o Magma collects in a magma __________ inside the Earth’s crust.
o The opening where magma is forced up and flows onto the Earth’s surface is called a __________.
o The __________-walled depression around a volcano’s vent is called the __________.
 __________ of Volcanoes
o Form at divergent & __________ plate boundaries.
o __________Spots :
 An unusually hot area between the __________ & core that forces melted rock upward to form
__________ in the middle of tectonic plates.
 Plate moves as the hot spot is __________.
 Volcanic __________
• The __________ of a volcano depends on:

Amount of water vapor & other gases trapped in the __________.
 Amount of __________ present in the magma.
- __________ lava is low in silica & produces __________, non-explosive eruptions: __________ & __________
- Granitic & andesitic magma are high to _____________ in silica & produce __________ eruptions.
4. Types of Volcanoes
 Shield
» __________ volcanoes with __________ sloping sides.
» Quiet eruptions of __________ lava forming flat layers.
 __________ Cone
» Steep-sided volcanoes made of loosely packed __________.
» Tephra- bits of rock or __________ lava (pyroclastic material) like ash, cinders, __________, & blocks.
 ______________
» Volcanoes with __________ layers of __________ & lava flows.
» Long __________periods
» __________eruptions
Intrusive Igneous Formations
 __________
• Largest intrusive formations
• Forms where magma has been forced up into __________ within the crust & __________ slowly.
 __________
• Magma that is forced into __________ cracks that cuts across rock layers and __________.
 __________
• Magma that has been forced into cracks that are __________ to rock layers and then hardens.
 __________ Necks
• The solid __________ rock core of an extinct volcano.
• __________ & erosion wear away the cone exposing the __________.
 __________
• Large __________ caused by the __________ of a crater during an eruption.