When existing rocks are subjected to high temperature and pressure, metamorphic rocks are formed. Metamorphism is a process by which these metamorphic rocks are formed. It is of three kinds:
Types of Metamorphism
Thermal metamorphism: Metamorphism caused by extreme temperature is called thermal metamorphism. It occurs because of the heat generated by magma or due to the friction caused by two moving rocks. Example: Forming of slate from clay
Dynamic metamorphism: It occurs when changes in rocks take place because of large-scale movements of the Earth’s crust. The rock may get pushed to greater depths under the surface of the Earth resulting in the formation of new rocks. Example: Shale gets converted to hornfels.
Regional metamorphism: When metamorphism is caused by large-scale changes such as mountain building, the igneous and sedimentary rocks may get buried to form new rocks. This is known as regional metamorphism. When only a small area is affected, it is called local or contact metamorphism. Example: Sandstone changes into quartzite.
Processes of Metamorphism
Mechanical metamorphism: It occurs when the texture of rocks is changed by crushing and rubbing processes. In this process, shales develop into slaty splits.
Chemical recombination: This process takes place when rocks containing more than one mineral are metamorphosed into one rock.
Chemical replacement: When liquids and gases enter the surface of the Earth through small cracks, they undergo chemical changes and new rocks are formed.
Recrystallization: It takes place when minerals present in rocks are changed into large crystals before metamorphism.
The igneous rocks are also known as primary rocks as they form the basis of the formation of other types of bricks. Igneous rocks are formed because of the cooling, solidification, and crystallization
Sedimentary rocks are formed when the fragments of igneous rocks are broken down because of weathering and are carried away by the agents of gradation such as water, glaciers, and ocean waves.
Intrusive igneous rocks are formed when magma cools and solidifies below the surface of the Earth. 5 types of intrusive igneous rocks are…
Important Uses of Rocks – Rocks have played a great part in the development of civilizations. Rocks are used in the construction of many buildings such as granite.
The process of the transformation of rocks from one form to the other in a cyclic manner is known as the rock cycle. It includes the following processes:
When the magma is forced in the upward direction, it fills the cracks and fissures in the existing rocks. It solidifies in these cracks forming dykes. Dykes are often vertical or slanting in position and are often an offshoot of rock.