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.