Ashstone
Encyclopedia
Ashstone is a kind of volcanic rock
formed from fine volcanic ash
.
During an explosive volcanic eruption
, fragmentation of the magma
can result in the formation of volcanic ash, consisting of sand-sized
or smaller particles.
After settling and consolidation this volcanic ash can be considered to be an ashstone; a more widely accepted term is tuff
.
Volcanic rock
Volcanic rock is a rock formed from magma erupted from a volcano. In other words, it is an igneous rock of volcanic origin...
formed from fine volcanic ash
Volcanic ash
Volcanic ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions, less than in diameter. There are three mechanisms of volcanic ash formation: gas release under decompression causing magmatic eruptions; thermal contraction from chilling on contact...
.
During an explosive volcanic eruption
Volcano
2. Bedrock3. Conduit 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...
, fragmentation of the magma
Magma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...
can result in the formation of volcanic ash, consisting of sand-sized
Sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
or smaller particles.
After settling and consolidation this volcanic ash can be considered to be an ashstone; a more widely accepted term is tuff
Tuff
Tuff is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption. Tuff is sometimes called tufa, particularly when used as construction material, although tufa also refers to a quite different rock. Rock that contains greater than 50% tuff is considered...
.