Question

What is crust and what is it mainly made up of ?

Answer 1

Hint: Earth's crust is an important layer which is extremely thin which is composed of rocks forming the outermost layer of our planet. It is equivalent to less than half of 1 percent of the planet's total volume, but it plays a vital role in most of the natural cycles that occur throughout the Earth. The Earth's crust is made up of various layers, each made up of different elements.

Complete answer:
Earth is not a flat surface, but a spherical planet that is made up of various layers. The innermost layer of earth is called Core. It is the hottest part and contains metals in a molten state. While the crust is the outermost layer, there is a middle layer in between this crust and the core which is called the mantle that is made up of rocks and magma in a semi-solid state.

There is no air or water in the core and the mantle and they are too hot for organisms to survive. It is the composition of earth’s crust that is of great importance to the world. The crust of the earth is a very thin layer made of different types of rocks. One can think of it in terms of the skin of an apple as the crust has a mass less than $1\%$ of the total mass of earth. The thickness of the crust is not uniform at all places.

The crust is made up of different types of rocks. But the three main types of rocks are: igneous, metamorphic, and sedimentary rocks. Igneous rocks (from the Latin word for fire) form when hot, molten rock crystallizes and solidifies into a rock. Rocks that undergo a change to form another rock are referred to as metamorphic rocks. Sedimentary rocks are formed by the deposition and subsequent cementation on the material at the Earth’s surface within the water bodies.

Note: Crust beneath the surface of the land masses is called the continental crust whereas the crust lying beneath the floor of the oceans is called oceanic crust. Continental crust is much thicker and older than oceanic crust.