We will discuss here about the rock, soil and minerals. Billions of years back the Earth was born from the Sun. At that stage it was a mass of burning gas like the Sun.
Gradually it lost its enormous heat and became cooler. In this process the outermost layer of the Earth was condensed and transformed into Mantle liquid. Under further process of cooling it became solid. If we can cut the Earth into two halves like a boiled egg we can see hot molten mass at its center. This is called magma.
Surrounding the magma we can see layers of different rocks. The outermost layer of the Earth is made up of very fine dust of rocks, several inorganic and organic matters and numerous micro-organisms. This is called the soil.
The soil and the rocks contain many minerals. Some rocks are special, which contain metallic or non-metallic minerals in large quantities. These rocks are called ores. By processing these ores we can extract metals like iron, copper, aluminium, etc. Millions of years back large quantity of organic matters went under the rocks due to natural disasters or other natural processes. Later those matters were transformed into coal and petroleum. Coal is the modified form of ancient vegetation. In those days there were vast swampy forests on the Earth. The trees of the forest, which laid on the swamp, got buried by subsiding the soft clay. Subsequently more and more sedimentary deposits were accumulated on it. Under increasing pressure and heat these partly decomposed plant-matters were transformed into coal.
Petroleum is considered to have been formed from the remains of living organisms (animal), which were deposited on the sea floor and got buried under sediments in course of time. Now we collect this from underground, refine it in refineries and use it as a fuel.