Rock Cycle
The lithosphere is made up of rocks. The formation of rocks on the earth surface happens in a certain definite order. Rock Cycle explains the process on the earth related with the formation of three types of rocks over a period of time and the transformation of rock from one type of rock to another form.
When the molten magma rises, gets cooled and solidified near or above the earth’s crust, igneous rocks are formed. This is the first type of rock to be formed known as the parent rock.  The igneous rock gets weathered, eroded, transported by various agents such as water, wind, waves and glaciers forming sediments. These materials deposited as layer after layer for a long period of time get compressed, compacted and cemented resulting in the formation of sedimentary rocks. The high pressure and temperature causes change in the composition of igneous and sedimentary rocks resulting in metamorphic rocks without disintegration of the pre existing rocks. This process is repeated in a cyclic manner and is known as a rock cycle.
Uses of Rocks
Rocks contain numerous valuable minerals and are used by us in one way or the other in our daily life. 
Some of the uses of rock are as listed below:
  1. Making Cement
  2. Writing Chalk
  3. Building Material
  4. Roofing Material Statue/Ornaments/Decoration (Marble)
  5. Fertilizers
  6. Valuable source of minerals (Gold, Diamond, Sapphire etc.).