The molten form of rock expelled onto the surface as well as spread inside the Earth's crust by the powerful volcano is called the Lava, and the structure formed after the solidifying of the molten Lava is called as the Lava rock. The geothermal energy is the heat source that liquefies the rocks inside the earth's crust. It is a form of igneous rock found on other planets too, but in the intrusive form. Eruption on the earth's crust causes the volcanic Lava to extrude on the earth's surface. The temperature that liquefies the rocks is between 700 to 1200 degree Celsius. The Lava is more vicious than water in nature by manifolds, and it spreads faster like the water to greater distances before solidifying due to its thinning property.
Thus, the outpouring of the Lava flow to the exterior part and its solidifying is shortly termed as Lava. During the Lava flow, other fragments referred as "Tephra" form a mixture with the molten rock. Lava derives from a Latin word "labes", meaning "a slide or fall". The name of the molten rock was first found in the short account, authored by Francesco Serao, based on the Vesuvius eruption, during 1737 from May 14 to June 4.
Morphology of Lava
The behavior of the molten Lava is very unpredictable. Usually the Rhyolite, Andesite, Trachyte and Dacite along with the cooled form of Basalt Lava are found highly viscous. The freshly outpoured Basalt, Andesite and Carbonatite are found less viscous. The highly vicious molten rocks flow slowly, and clog to form blocks in the semi-solid form that restrict the flow, whereas the low viscosity Lava flows easily that forms puddles, rivers and channels of Lava. It easily liberates the bubbling gases as soon as they are developed. Different types of molten Lava result in different types of flows and structures. Basically, the Basalt-Lava tends to form a sheet like structure, whereas the Rhyolite Lava forms clogs and block the flow. The top part of the Lava always results into a glassy form. The immediate contact with the water or air causes the top of the Lava to freeze and form such a glassy structure. The middle part of the Lava is found to be crystalline and massive. The base part is mostly found to constitute of vesicles and minerals.
Minerals from Lava
The outpouring of the molten rock on the earth's surface is called Lava, whereas the eruption of molten rock inside the crust is called magma. The Lava tends to cool down quickly due to the contact with air and water in contrast to the magma inside the earth's crust This results in the quick formation of rock in the exterior part and the mineral crystals present in the rock are found to be very fine in texture. For example the Rhyolite rock is formed when the Lava is cooled, where as the Granite rock is evolved from the cooling of the magma. Though both of the rocks consist of similar minerals, the texture of the minerals are very different. The mineral crystals in the Rhyolite rock are much finer than the Granite crystals.
Different types of molten Lava form different types of landform. Some of the commonly seen Lava forms are-:
- Lava Tubes
- Lava Lakes
- Lava Domes
- Spatter and Cinder Cones
- Lava Delta