INTRUSIVE ROCK Meaning and
Definition
-
Intrusive rock, also known as plutonic rock or subterranean rock, is a type of igneous rock that forms beneath the Earth's surface through the solidification of molten rock material, known as magma. It is contrasted with extrusive rock, which is formed when molten rock erupts onto the Earth's surface and cools rapidly, such as volcanic rock.
Intrusive rocks are characterized by their coarse-grained texture, with individual mineral crystals visible to the naked eye. This is because their slow cooling process allows enough time for mineral crystals to grow. The size of the mineral crystals within intrusive rocks varies depending on the rate of cooling and the composition of the magma.
Examples of intrusive rocks include granite, diorite, and gabbro. These rocks possess a wide range of mineral compositions, as they can form from different magmas with varying chemical compositions. Granite, for instance, is primarily composed of minerals such as quartz, feldspar, and mica. These rocks are often found in large bodies or structures deep within the Earth's crust, called plutons.
Intrusive rocks are considered significant in geology due to their ability to provide insights into the Earth's history. By studying the mineral composition, texture, and relationship to surrounding rocks, geologists can gain an understanding of the processes and conditions that occurred during their formation. Intrusive rocks can also uplift and erode, gradually allowing them to become exposed at the Earth's surface over millions of years of geological activity.
Etymology of INTRUSIVE ROCK
The word "intrusive" in the term "intrusive rock" originated from the Latin word "intrudere", which means "to thrust oneself in". It was derived from the combination of the prefix "in" meaning "into", and the root "trudere" meaning "to push or thrust".
The term "intrusive rock" refers to a type of igneous rock that forms from the cooling and solidification of magma beneath the Earth's surface, intruding into pre-existing rocks. These rocks are called "intrusive" because they forcibly push their way into the existing rock layers, often causing visible deformation and displacement.
