This document discusses the three main types of rocks: igneous, sedimentary, and metamorphic. Igneous rocks form from the cooling and solidification of molten material either underground or on the surface. Sedimentary rocks form from the compaction and cementation of sediments and often feature distinct layers. Metamorphic rocks form from changes to existing igneous or sedimentary rocks through heat, pressure, and chemical processes. Rocks have played an important role in human civilization from early stone tools to the progress of modern society.

1. WELCOME

2. ROCKS

3. WHAT IS ROCK
• The materials of the crust or lithosphere are generally called as rocks.
• A rock is a solid aggregate of grains of a single mineral or more than
one mineral.
• More than one element of earth’s crust are organized to form minerals.
• Minerals are organized to form rocks.

4. CLASSIFICATION
• On the basis of origin rocks are classified into three.
• They are
• IGNEOUS ROCKS
• SEDIMENTARY ROCKS
• METAMORPHIC ROCKS

5. IGNEOUS ROCK
• The word igneous has been derived from Latin word (Ignis) meaning
there by fire.
• Forms both on the surface of the earth and in the interior of the
earth.
• Formed due to cooling , solidification and crystallization of hot and
molted materials.
• Is called primary rock because it formed first.
• Called parent rock

6. IGNEOUS ROCK

7. SEDIMENTARY ROCKS
• The word sedimentary has been derived from Latin word ‘sedimentum’
which means setting down.
• Also called as stratified or layered rocks.
• Because these rocks have different layers or strata of different types of
sediments.
• Some times layers are absent in some sedimentary rocks ,example
loess.
• This can be classified on the basis of mode of origin.

8. SEDIMENTARY ROCK

9. METAMORPHIC ROCKS
• The word metamorphism has been derived from the word ‘metamorphose’
which means change in form.
• Metamorphic rocks are generally formed due to changes in form of
sedimentary and igneous rocks.
• Some times ,even previously formed metamorphic rocks are again
metamorphosed.
• Metamorphic rocks are the most common rocks found in kerala.

10. METAMORPHIC ROCKS

11. CONCLUSION
• Ever since human beings appeared on earth, they have been
depending on rocks for various purposes.
• The earliest weapons used by man were made of stones. Later on he
learned to make fire by rubbing stones together.
• In the progress of human civilization rocks played a major role.