Question

How can igneous rocks become metamorphic rocks?

Answer 1

Hint: Rocks are always changing as the earth is dynamic in nature. Minerals that makeup rocks are constantly moved and acted upon by the environment. The agents of the environment change one type of rock into an entirely new rock. The web of environmental processes that form and change rocks is known as the rock cycle.

Complete answer: The name igneous had been derived from the Latin word ‘Ignis’ meaning fire. These rocks are formed from the consolidation of magma or molten rock material from the interiors of the earth. Magma when brought to the surface of the earth is known as lava. Lava forms volcanic rocks. The cooling of the lava can take place both inside as well as outside the earth's surface. The cooling process and the time taken for the lava to cool decide the texture and grains of the rocks. For instance, slow cooling of the lava results in large grain formation which may take place at great depth. Fast or sudden cooling of the lava results in smooth and small grain formation and intermediate cooking of the lava results in the formation of grains of intermediate sizes.

The term metamorphic is derived from Greek words which literally means change and form. The metamorphic rocks are framed from previously molten rock material which has been changed because of incredible warmth and pressure. At the point when the rocks are constrained down to the lower levels by the structural powers and exposed to incredible pressure by the overlying rocks, the previously consolidated rocks go through revamping and recrystallization acquiring the required nature of the rocks.
Two types of metamorphic rocks are
- Foliated metamorphic rocks have a layered or banded appearance which is produced by directed pressure and exposure to heat such as gneiss, schist and slate.
- Non-foliated metamorphic rocks do not have a layered or any banded appearance. Example of this kind of rock is quartzite and marble.

Note: The two types of igneous rocks are plutonic igneous rocks and volcanic igneous rocks. Plutonic rocks are formed when the molten magma cools and solidifies slowly before it gets to the surface of the earth to form large crystals. Examples of plutonic rocks are diorite, granite and gabbro. Volcanic rocks are formed when the molten magma cools and solidifies rapidly the moment it reaches the earth surface to form small crystals, for example, basalt.