| A | B |
|---|
| Basin | A broad, bowl-shaped valley. |
| Caldera | Huge hole left by the collapse of a volcanic mountain. |
| Volcanic neck | Forms when magma hardens in a volcano's pipe. |
| Dike | Forms when magma forces its way across rock layers. |
| Sill | Forms when magma forces its way between rock layers. |
| Intrusion | When magma hardens underground to form igneous rock. |
| Composite volcano | Tall, cone shaped mountain that forms when layers of lava alternate with layers of ash. |
| Cinder Cone | Steep, cone shaped mountain hill that is formed from explosive eruptions of cinders, ash and bombs |
| Shield volcano | Wide, gently sloping mountain created by layers of lava that harden on top of previous layers. |
| Geyser | Fountain of water and steam that erupts from the ground |
| Extinct | Unlikely to erupt again |
| Dormant | Sleeping volcano |
| Active | Erupting or likely to erupt in the near future |
| Pyroclastic flow | Explosive eruption that hurls out ash, gases, cinders, and bombs. |
| Silica | Formed from elements of silicon and oxygen |
| Pumice and Obsidian | Igneous rocks formed from high silica lava |
| Crater | A bowl-shaped area at the top of a volcano around the central vent |
| Lava flow | Area covered by lava as it flows out of a vent |
| Vent | Opening through which molten rock and gases leave a volcano |
| Pipe | Long tube that connects magma chamber to Earth's surface |
| Magma chamber | A pocket beneath a volcano where magma collects |
| Hot spot | An area where material erupts through the crust like a blow torch. Usually found in the middle of plates. |
| Island Arc | String of volcanic islands created where two oceanic plates collide |
| Ring of Fire | Major volcanic belt formed around the rim of the Pacific Ocean. |
| Magma | A mixture of molten materials, gases, and water from the mantle |
| Lava | When magma reaches the surface it turns to this. |
| Volcano | A weak spot in the Earth's crust where molten material reaches the surface |
