| A | B |
|---|
| aa | A slow moving type of lava that hardens to form rough chunks; cooler than pahoehoe. |
| batholith | A mass of rock formed when a large body of magma cools inside the crust. |
| caldera | The large hole at the top of a volcano formed when the roof of a volcano's magma chamber collapses. |
| chemical property | Any property of a substance that produces a change in the composition of matter. |
| cinder cone | A steep, cone-shaped hill or small mountain made of volcanic ash, cinders, and bombs piled up around a volcano's opening. |
| composite volcano | A tall, cone-shaped mountain in which layers of lava alternate with layers of ash and other volcanic materials. |
| compound | A substance in which two or more elements are chimically joined. |
| crater | A bowl-shaped area that forms around a volcano's central opening. |
| dike | A slab of volcanic rock formed when magma forces itself across rock layers. |
| dormant | Describes a volcano that is not currently active, but that may become active in the future. |
| element | A substance that cannot be broken down into other substance. |
| extinct | Describes a volcano that is no longer active and is unlikely to erupt again. |
| geothermal activity | The heating of underground water by magma. |
| geyser | A fountain of water and steam that builds up pressure underground and erupts at regular intervals. |
| hot spot | An area where magma from deep within the mantle melts through the crust above it. |
| island arc | A string of islands formed by the volcanoes along a deep-ocean trench. |
| lava | Liquid magma that reaches the surface; also the rock formed when liquid lava hardens. |
| lava flow | The area covered by lava as it pours out of a volcano's vent. |
| magma | The molten mixture of rock-forming substances, gasses, and water from the mantle. |
| magma chamber | The pocket beneath a volcano where magma collects. |
| pahoehoe | A hot, fast-moving type of lava that hardens to form smooth, ropelike coils. |
| physical property | Any characteristic of a substance that can be observed or measured with changing the composition of the substance. |
| pipe | A long tube through which magma moves from the magma chamber to Earth's surface |
| pyroclastic flow | The expulsion of ash, cinders, bombs, and gases during an explosive volcanic eruption. |
| Ring of fire | A major belt of volcanos thatt rims the Pacific Ocean |
| shield volcano | A wide, gently sloping mountain made of layers of lava and formed by quiet eruptions. |
| silica | A material found in magma that is formed from the elements oxygen and silicon. |
| sill | A slab of volcanic rock formed when magma squeezes between layers of rock. |
| vent | The opening through which molten rock and gas leave a volcano. |
| viscosity | The resistance of a liquid to flowing. |
| volcanic neck | A deposit of hardened magma in a volcano's pipe. |
| volcano | A weak spot in the crust where magma has come to the surface. |
