Types of rocks

Types of rocks

There a three major types of rocks based on their formation and they are
• Igneous Rocks
• Sedimentary Rocks
• Metamorphic Rocks

1) Igneous Rocks - With the name Igneous is derived from the Latin word Ignis which means fire. So, Igneous are formed when the molten matter inside the Earth called magma comes out of the volcano and later cools down and solidifies.
There are 2 types of igneous rocks. When the magma cools down and solidifies inside the Earth’s surface they are known as Intrusive Igneous Rocks. When the magma erupts above the Earth’s surface and solidifies they are known as Extrusive Igneous Rocks. Pumice and Granite are some examples of Igneous rocks.

2) Sedimentary Rocks - Sedimentary rocks as the name suggests are comprised of sediments. These sediments could be minerals, small pieces of plants and other organic matter that have been compressed and deposited over a long time. These rocks can be generally found on the ocean and lake beds. And on rocky surfaces on the Earth’s crust sandstone and coal are some of the examples of the sedimentary rocks.

3) Metamorphic Rocks - When the igneous and sedimentary rocks are exposed to high temperatures and pressures, they undergo change and this process of changing from one form of rock to another is called Metamorphism. But that takes a really long time mainly 1000s of years. However, this process doesn’t melts the rocks but instead transforms them into denser more compact rocks. Slate and Marble are the some examples of the metamorphic rocks.

Did you know, the upper segment of the Earth’s crust is made up of about 95% of igneous rocks. The Taj Mahal in India is completely made up of different types of Marble a metamorphic rock.