You must have seen the hard substances as shown in the figure alongside. These hard substances are rocks. The Earth contains such rocks inside and on its surface. Rocks are made up of different types of minerals which have different textures, colours, and densities. Soil is formed by breaking down these rocks. Thus, soil contains pieces of rocks in it.
Rocks forming naturally on Earth's surface
The water flowing in rivers and falls carries soil, sand, and dead bodies of animals, plants, and their parts with it. These materials are deposited at the bottom of rivers and seas. When such materials remain pressed for a very long time by the deposition of sediments over them every year, they are hardened in the form of rocks after many years.
Some rocks are hard and some are soft. Various types of rocks have different colours. They may have fine or coarse particles in them. They may have rough or smooth surfaces. Some rocks break into flakes and some into non-flakes when hammered.