SUBVOLCANIC ROCK Meaning and
Definition
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Subvolcanic rock is a type of igneous rock that forms when magma, or molten rock, cools and solidifies beneath the Earth's surface, specifically in the upper crust. It is characterized by its composition, texture, and mode of formation.
Composition: Subvolcanic rocks are primarily composed of minerals such as quartz, feldspar, and mica, but their specific mineralogy can vary depending on the original composition of the magma. They may also contain other trace minerals like amphibole, pyroxene, or olivine.
Texture: Subvolcanic rocks display a fine-grained texture due to their slow cooling rate beneath the surface. Unlike volcanic rocks that cool rapidly above ground, the slower cooling process of subvolcanic rocks allows for the development of small mineral crystals that are not fully visible to the naked eye.
Formation: Subvolcanic rocks originate from magma that rises towards the surface but gets trapped in underground chambers, known as plutons or stocks. The magma then cools and solidifies over a long period, forming subvolcanic rocks. These rocks are typically associated with batholiths, which are large and deeply rooted intrusive igneous bodies.
Due to their geological origin, subvolcanic rocks often exhibit excellent durability and can be resistant to weathering and erosion. They are commonly found in areas with a history of volcanic or tectonic activity, such as mountain ranges or regions with active or extinct volcanoes. Examples of subvolcanic rocks include diorite, granodiorite, and tonalite.
Overall, subvolcanic rocks provide valuable insights into the formation and evolution of the Earth's crust, and they have various applications in construction, ornamental stone production, and geological research.
Etymology of SUBVOLCANIC ROCK
The word "subvolcanic" is formed by combining the prefix "sub-" meaning "below" or "lesser" with the term "volcanic", which refers to anything related to volcanoes.
The term "volcanic" has its etymology in the Latin word "volcanicus", which ultimately originates from "Vulcanus", the Roman god of fire, including volcanoes.
Regarding the term "rock", it comes from the Old English word "rocc" which means "stone". Its usage has been carried forward, unchanged, into Modern English.
