Volcano Key Terms

Volcano

A weak spot in the crust where magma comes to the surface.

Magma

A molten mixture of rock-forming substances, gas and water from the mantle.

Lava

Magma that has reached the surface.

Ring of Fire

The major volcano belt surrounding the Pacific ocean.

Island Arc

The resulting volcanoes create a string of islands.

Hot Spot

an area where material from deep within the mantle rises and then melts, forming magma.

Element

A substance that broken down into other substances. some examples are oxygen,Carbon,and Hydrogen.

Compound

A substance made of two or more elements that have been chemically combined.

Physical Property

Any characteristic of a substance that can be observed without changing the composition of what you are observing.

Chemical property

A characteristic that actually produces a change in its composition.

Viscosity

The resistance of a liquid to flowing. Something with high viscosity has particles that like to stick together

Silica

Something that is made up of particles of the elements of the elements oxygen and silicon.

Pahoehoe

Fast moving hot lava that has low viscosity.

aa

Slow moving lava that has more viscosity than than pahoehoe.

Magma Chamber

A pocket of magma underneath a volcano.

Pipe

A long tube that magma flows through.

Vent

Where lava leaves through an opening.

Lava flow

the area covered by lava as it pours out of a volcano's vent.

Crater

A bowl- shaped area that many will form at the top of a volcano.

Pyroclastic flow

This occurs when an explosive eruption hurls out a mixture of hot gasess, ash, cinders, and bombs.

Dormant

A volcano that is like a sleeping bear. Scientists expect these volcanoes to erupt sometime in the future.

Extinct

A "dead volcano that is unlikely to erupt again.

Shield volcano

A volcano with lots of thin layers, a gently sloping hill, and a slow lava flow.

Cinder Cone

A volcano that has a tall cone-shaped hill or small mountain and is the most violent.

Composite Volcano

A tall cone-shaped mountain that go from being slow volcanoes to violent ones.

Caldera

a volcano that is so explosive that its magma chamber collapses.

Volcanic neck

When magma hardens inside of a volcano and the volcano is weathered away.

Dike

Tales advantage of the cracks in rock. Magma forces itself through this crack.

Sill

When magma squeezes itself through horizontal layers of rock.

Batholith

A giant rock formed when magma cools.

Geothermal Activity

activity caused by Earth;s heat such as hot-springs and geysers.

Geyser

A fountain of water and steam that erupts from the ground.