Volcanos
What is a volcano
How volcanos form
Where do volcanos form
a volcano is a vent in earth's crust that molten lava can flow through.
Magma is molten rock below earth's surface.
The movement of earth's tectonic plates causes volcanos to form.
volcanos form along convergent and divergent boundaries.
Hot spots are not along plate boundaries.
The ring of fire is an area of volcanic activity around the pacific ocean.
There are 60 active volcanos in the United States.
Types of volcanos
Sheild volcanos- large with gentle slopes with basaltic lavas. common along divergent plate boundaries. Look like hills.
Composite volcanos- large and steep sided that result from lava and ash. commonly along convergent plate boundaries.
Cinder cones- small steep sided and erupt basaltic lavas.
Volcanic Eruptions
volcanic ash- tiny particles of pulvarized volcanic rock and glass high into the atmosphere
silica- the main chemical compound in all magmas.
viscosity- a liquid's resistance to flow
Lava-above surface molten, Magma-below surface.
parts of a volcano
Vent- opening at the top
crater- top bowl shaped area
pipe- leads from bottom to top
magma chamber- at the bottom where the lava is
Side vent- opening on the side of the volcano
ash cloud- what is released from the top
lava flow
quiet eruption- lava runs down the side
Explosive eruption- when vent is blocked
Mount St. Helens
Nickednamed coughing Mountain
named in 1792
March 16-May 18 was the most activity
Myths and legends
Pompeii- They made sacrifices Vulcan and thought he was grumbling. located on mount vesuvius. 13-20 feet of volcanic ash.