[Physics Class Notes] on Metamorphic Rocks Pdf for Exam

They are a class of rocks that result from the alteration of pre-existing rocks in response to changing environmental conditions or any natural situations without any liquefaction process, such as fluctuations with temperature, pressure, and mechanical stress, and the inclusion or subtraction of any available chemical components.

Definition and Examples

Metamorphic rocks arise from the transformation of existing natural rock substances to new types of rock without any exterior liquefaction manually done, in a process called metamorphism. During this process, the original rock is subjected to temperatures of more than 150-200 degrees celsius and often pressures of more than 100 megapascals resulting in vast physical and chemical modifications.

Types and Characteristics

Common metamorphic rocks varieties include phyllite, schist, gneiss, quartzite, and marble. 

Metamorphic rocks can be classified into two main categories based on the way they are formed – those that are foliated as they have been formed due to high pressure and under shear stress and those that are not foliated under any form of pressure. 

Types of Metamorphism

The three major types of metamorphism are Contact, Regional, and Dynamic metamorphism.

• Contact Metamorphism occurs when hot lava comes in contact with an already existing body of rock. When this happens the existing rock’s current temperature rises and also becomes infiltrated with fluid from the volcano. 

• Regional Metamorphism occurs over a much larger surface area. This type of metamorphism produces and forms rocks such as gneiss and schist. Regional metamorphism is mainly caused by large geologic processes such as mountain-building.

• Dynamic Metamorphism, like regional metamorphism, also occurs because of mountain-building. These huge forces of heat and pressure that are applied naturally cause the rocks to be bent, folded, crushed, flattened, and sheared in any manner. As hard as or even harder than igneous rocks, metamorphic is almost always harder than sedimentary rocks. They form the roots of many mountain chains and are exposed to the surface after the softer outer layers of rocks are eroded away due to any natural calamities caused.