volcanoes
What forms after volcano eruption and after magma cools?
Igneous rock forms when superheated volcanic liquid, also called magma, cools and thus hardens through a process of crystallization in one of two manners: by cooling and crystallization on the Earth’s surface such as after a volcanic eruption; or by cooling more gradually through a process of rising as it cools through the magma while still below the Earth’s surface. Scientists further classify such rocks based on their mineral characteristics: pumice has a light weight and a light color and is made up mostly of holes known as vesicles left behind by the past presence of gases; vesicular rock also has many holes previously occupied by gas and has a Swiss cheese appearance; and obsidian is a darker glassy-looking volcanic rock.
Metamorphic Rock
A metamorphic rock forms through geological forces applied to the rock that have caused it to turn from one type to another, leaving evidence behind of the process. While most commonly this involves conversion through pressure from a sedimentary to a metamorphic rock, this can also involve a process whereby the flow of superheated lava over the area surrounding an erupted volcano changes the form of some of the existing rock from both sedimentary and igneous rocks into a metamorphic rock such as is the case with some forms of granite.
PARTS OF A VOLCANO
cross-section through a stratovolcano(vertical scale is exaggerated):
1. Large magma chamber2. Bedrock3. Conduit (pipe)4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank
9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15. Ash cloud
Why do volcanoes erupt?
Hot melted rocks collect under the Earth's surface and when the pressure becomes too hard, the Earth's skin breaks, and a volcano erupts. The melted rock inside the Earth is called magma, but when it comes out in an eruption, it is called lava.
Plates are like the Earth's skin. They are
Igneous rock forms when superheated volcanic liquid, also called magma, cools and thus hardens through a process of crystallization in one of two manners: by cooling and crystallization on the Earth’s surface such as after a volcanic eruption; or by cooling more gradually through a process of rising as it cools through the magma while still below the Earth’s surface. Scientists further classify such rocks based on their mineral characteristics: pumice has a light weight and a light color and is made up mostly of holes known as vesicles left behind by the past presence of gases; vesicular rock also has many holes previously occupied by gas and has a Swiss cheese appearance; and obsidian is a darker glassy-looking volcanic rock.
Metamorphic Rock
A metamorphic rock forms through geological forces applied to the rock that have caused it to turn from one type to another, leaving evidence behind of the process. While most commonly this involves conversion through pressure from a sedimentary to a metamorphic rock, this can also involve a process whereby the flow of superheated lava over the area surrounding an erupted volcano changes the form of some of the existing rock from both sedimentary and igneous rocks into a metamorphic rock such as is the case with some forms of granite.
PARTS OF A VOLCANO
cross-section through a stratovolcano(vertical scale is exaggerated):
1. Large magma chamber2. Bedrock3. Conduit (pipe)4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank
9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15. Ash cloud
Why do volcanoes erupt?
Hot melted rocks collect under the Earth's surface and when the pressure becomes too hard, the Earth's skin breaks, and a volcano erupts. The melted rock inside the Earth is called magma, but when it comes out in an eruption, it is called lava.
Plates are like the Earth's skin. They are