| A | B |
|---|
| theory | unproven data |
| crust | thin, outer surface of the earth |
| mantle | layer of earth on which crust floats |
| core | innermost part of the earth |
| tectonic plates | sections of the crust that move independently |
| fault | a break in the earth's crust |
| lava | magma that has reached the earth's surface |
| magma | hot molten rock inside earth |
| Ring of Fire | highly active volcanic area around the Pacific Ocean |
| Mt. St. Helens | erupted in Washington on May 18, 1980 |
| shield volcano | a volcano with broad, gently-sloping sides |
| dormant | an inactive volcano |
| ash | fine-grained pyroclastic material |
| cinder cone volcano | a cone-shaped volcano made of loose fragments |
| crater | depression at or near the top of a volcano |
| flow | lava movement |
| eruption | an exploding volcano that spews solid, liquid, and gaseous materials |
| volcanology | the study of volcanoes |
| volcanologists | people who study volcanoes |
| strato volcano | a volcano made of both lava and pyroclastic material |
| pyroclasts | volcanic material that comes out in fragments |
| bombs | large, fluid pieces of molten rock |
| blocks | large, solid pieces of molten rock |
| volcano | a mountain build by eruptions |
| Mayon | the most recent active volcano located in the Philippines |
