iasindepth

empowering millions

Premium Civil Service course at just ₹99/-. Know more.

UPSC Mains 2022

Describe the characteristics and types of primary rocks.

General Studies Paper - 1, Topic - Physical Geography

Dec 28, 2022

2 min read

Recorded lectures

Class tests

Class notes

Buy now

Primary rocks are those that form directly from the solidification of magma or lava. They are considered to be the most basic and fundamental type of rock, as they are the building blocks from which other rocks are formed. Primary rocks can be divided into two main categories: igneous rocks and metamorphic rocks.

 

Igneous rocks are formed when molten magma cools and solidifies either below or above the Earth's surface. If the magma cools slowly and at great depths, it becomes a coarse-grained rock called plutonic rock. Examples include granite and gabbro. If the magma cools quickly at the surface, it becomes a fine-grained rock called volcanic rock. Examples include basalt and pumice.

 

Metamorphic rocks are formed when preexisting rocks are subjected to extreme heat and pressure, causing them to change in composition and structure. These rocks can be further divided into two categories: foliated metamorphic rocks, which have a layered or banded appearance, and non-foliated metamorphic rocks, which do not have a layered appearance. Examples of foliated metamorphic rocks include slate and gneiss, while examples of non-foliated metamorphic rocks include marble and quartzite.

 

In summary, primary rocks are formed directly from the solidification of magma or lava and can be divided into two main categories: igneous and metamorphic rocks. Igneous rocks are formed from the cooling of magma, while metamorphic rocks are formed from the transformation of preexisting rocks under extreme heat and pressure.

Free daily current affairs quiz.

Take this test daily to improve your prelims accuracy.

More on iasindepth