Lava   Study & Career    Geography    History    Music    Quiz    Book Reviews    Terms & Glossory    Science    Fun & Trivia
   Home > Geography > Lava
Lava

LavaLava is molten rock expelled by a volcano during an eruption. Below the earth`s surface, molten rock is termed magma instead of lava. Lava, when first exuded from a volcanic vent, is a liquid at temperatures typically from 700 C to 1,200 C (1,300 F to 2,200 F). Although lava is quite viscous, about 100,000 times the viscosity of water, it can flow great distances before eventually cooling and solidifying. Lava solidifies to form igneous rock. The term "lava flow" refers to the hardened formation, whereas the one still having molten rock associated, is called an "active lava flow".

Lava FlowLava Flow is an outpouring of lava onto the land surface from a vent or fissure. Also, a solidified tongue like or sheet like body formed by outpouring lava. In general, a lava`s composition determines its behavior more than the temperature of its eruption. Igneous rocks, which form lava flows when erupted, can be classified into three chemical types; felsic, intermediate, and mafic. These classes are primarily chemical; however, the chemistry of a lava also tends to correlate with the magma temperature, its viscosity and its mode of eruption. The viscosity of lava is important because it determines how the lava will behave.

Highly viscous lava shows the following behaviors:

It tends to flow slowly, clog, and form semi-solid blocks which resist flow

Lava Bubbles It tends to entrap gasses, which form bubbles within the rock as they rise to the surface

It correlates with explosive or phreatic eruptions and is associated with tuff and pyroclastic flows Highly viscous lavas do not usually flow as liquid, and usually form explosive fragmental ash and cinder deposits. However, a degassed viscous lava or one which erupts somewhat hotter than usual may form a lava flow. Viscous lavas have two forms of non-pyroclastic eruptions, lava domes and sheeted flows. Lava with low viscosity shows the following behaviors:

It tends to flow easily, forming puddles, channels, and rivers of molten rock

It tends to easily release bubbling gases as they are formed

Eruptions are rarely pyroclastic and are usually quiescent

Volcanoes tend to form as rifts, not steep cones

More Interesting Readings
Aquatic Biome Deserts Earthquake
Forest Glacier Grasslands
Lava Plate tectonics Tornadoes
Tunadra An estuary Coral Reefs
Hurricanes Island Lake
Tsunami Geo Facts Plants & Animals
Plant Paradise
Indianetzone.com | Home | Contact Us