Term |
Definition |
Volcano |
A weak spot in earth's crust where molten material, or magma, comes to the surface. |
Lava |
When magma reaches the surface it's called this. |
Magma |
A molten mixture of rock-forming substances, gases, and water from the mantle is referred to as this. |
Volcanic ash |
Very small solid particles ejected from a volcano during an eruption. |
Magma chamber |
A large, underground pool of magma that is found beneath the surface of the earth. |
Crater |
A large, bowl-shaped cavity in the ground or on the surface of a planet or moon, typically one caused by an explosion or the impact of a meteor or other celestial body. |
Vent |
An opening in earth's surface from which molten material, as lava, steam or gas is emitted. |
Pipe |
A vertical conduit below a volcano in which magma has passed and that has become full with solidified magma, volcanic breccia, and fragments of older rock. |
Lava flow |
A stream or sheet of molten or solidified lava. |
Ring of Fire |
An area in the basin of the Pacific Ocean where a large number of earthquake and volcanic eruptions occur. |
Element |
A substance that cannot be broken down into other substances. |
Viscosity |
The physical properties of liquids ,called this,is the resistance of a liquid to flow. Depends on the silica content and temperature. |
Silica |
Made up of the elements oxygen and silicon, is one of the most abundant materials in Earth's crust. |
Pahoehoe |
A fast moving, hot lava that has low viscosity. |
Aa |
Lava that is cooler and slower-moving. It has higher viscosity than pahoehoe. |
Compound |
A substance made up of two or more elements that have been chemically combined. |
Subduction |
The sideways and downward movement of the edge of a plate of the earth's crust and mantle beneath the other plate. |
Extinct |
A volcano that is unlikely to ever erupt again. |
Dormant |
A volcano that is no longer active, but may become active again. |
Active |
A volcano that is erupting or showing signs that it will erupt soon. |
Cinder cone volcano |
When ash, cinders, bombs pile up around the vent which forms a steep, cone shaped hill or mountain. |
Shield volcano |
When thin layers of lava pour out of a vent and more layers of such lava build on the previous layer. This gradually build a wide, gently sloping mountain. |
Composite volcano |
Sometimes lava flows alternate with explosive eruptions of ash, cinders, and bombs. The alternating layers form a tall, cone-shaped mountain. |
Caldera |
A large hole formed when a volcano's magma chamber empties and causes the volcano to collapse. |
Batholith |
A mass of rock formed when magma cools inside the crust. |
Lava plateau |
Some eruptions of thin, runny lava flow out of cracks and travel a long distances before cooling and hardening. Over millions of years, the layers build up over a large area to form this. |
Sill |
A slab of rock that forms when magma squeezes between layers of rock. |
Dike |
A slab of rock that forms when magma forces itself across rock layers. |
Hot-spring |
A spring of naturally hot water, typically heated by geothermal energy. |
Geyser |
A fountain of hot water and steam that erupts from the ground. |