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The word lava comes from Italian and is probably derived from the Latin word labes, which means a fall or slide. [2] [3] An early use of the word in connection with extrusion of magma from below the surface is found in a short account of the 1737 eruption of Vesuvius, written by Francesco Serao, who described "a flow of fiery lava" as an analogy to the flow of water and mud down the flanks of ...
Shallow intrusions, which possess structure similar to volcanic rather than plutonic rocks, are also considered to be volcanic, shading into subvolcanic. [citation needed] The terms lava stone and lava rock are more used by marketers than geologists, who would likely say "volcanic rock" (because lava is a molten liquid and rock is solid).
The tendency of felsic lava to be cooler than mafic lava increases the viscosity difference. The silicon ion is small and highly charged, and so it has a strong tendency to coordinate with four oxygen ions, which form a tetrahedral arrangement around the much smaller silicon ion. This is called a silica tetrahedron. In a magma that is low in ...
Basalt is the most common extrusive igneous rock [9] and forms lava flows, lava sheets and lava plateaus. Some kinds of basalt solidify to form long polygonal columns. The Giant's Causeway in Antrim, Northern Ireland is an example.
Extrusive rock refers to the mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently into the atmosphere to fall back as pyroclastics or tuff. [1] In contrast, intrusive rock refers to rocks formed by magma which cools below the surface. [2]
Molten rock (either magma or lava) near the atmosphere releases high-temperature volcanic gas (>400 °C). In explosive volcanic eruptions, the sudden release of gases from magma may cause rapid movements of the molten rock. When the magma encounters water, seawater, lake water or groundwater, it can be rapidly fragmented.
For instance, water causes magma to cool and solidify much more quickly than in a terrestrial eruption, often turning it into volcanic glass. The shapes and textures of lava formed by submarine volcanoes are different from lava erupted on land. Upon contact with water, a solid crust forms around the lava.
The types of minerals present in volcanic ash are dependent on the chemistry of the magma from which it erupted. Considering that the most abundant elements found in silicate magma are silicon and oxygen, the various types of magma (and therefore ash) produced during volcanic eruptions are most commonly explained in terms of their silica content.