What are rocks?

Rocks are under every field, river and town.

Rocks all around

The Earth is made of rock. Rock is under the soil, the rivers and the sea. Rock is a natural material.

Rocks can be hard or soft, heavy or light, and many different colours.

Rocks can be as big as a mountain. A pebble is a small, smooth rock. Sand is made of tiny grains of rock.

Water rolls pebbles along for many years until they become smooth and round.

Rocks can be different colours. Some are rough. Some are smooth. Some have shiny crystals in them.

The shiny grains in granite are crystals. They formed when hot, melted rock cooled very slowly.

Most of Bangladesh is soft river mud. But in Sylhet, rivers carry many pebbles and stones from the hills. People collect them at Jaflong.

The stones come down from the hills with the river water. They are used for building roads.