1. ROCKS .

2. ROCKS ARE, ALL MATERIALS THAT MAKE UP THE EARTH’S CRUST.
Refers to hard materials like granite as well as soft and loose particles like sand, silt and clay. They are made up of minerals in different compositions.

3. Minerals
Minerals are naturally occurring solid inorganic substances having definite chemical composition and physical properties.
Are usually crystalline in appearance.

4. TYPES OF ROCKS
IGNEOUS ROCKS
SEDIMENTARY ROCKS
METAMORPHIC ROCKS

5. IGNEOUS ROCKS Derived from the latin word ïgnis”, meaning fire.
Also known as primary rocks as they were the first rocks to be formed.
Cooling and solification are the processes involved in formation of rocks.

6. FORMATION OF IGNEOUS ROCKS

7. INTRUSIVE AND EXTRUSIVE

8. Egs of intrusive igneous rocks(Plutonic rocks). Granite and Diorite
Rate of cooling is slower so they have larger crystals

9. Extrusive Igneous Rocks Egs Andesite and Basalt
Rate of cooling is faster so these have finer crystals.

10. Igneous rocks(Chemical composition)
Ultra basic- consists of ferre and magnesium.
Acidic-Light coloured and less dense. Eg, granite
Basic –contain lower % of silica and higher%of denser materials.Are denser and darker in colour than acidic rocks.

11. SEDIMENTARY ROCKS
Derived from the word sedimentum-meaning settling down.
Sediments deposited in layers or strata and hence these rocks are called stratified rocks.
Are porous and permeable.
Lithification-process of cementation, compaction and hardening of sediments into sedimentary rocks.
Also called secondary rocks because they are derived from primary rocks.
Contain fossils as these get preserved between the strata.

12. Formation of Sedimentary rocks

14. Sedimentary rocks
Mechanically formed-derived from the process of denudation. Egs- conglomerate, sandstone.
Organically formed-derived from accumulation of remains of organisms. Eg, Coal,corals.
Chemically formed-derived from process of evaporation of water containing salts. Eg. Rock salt, gypsum and potash.

15. Egs of Sedimentary rocks

16. Sedimentary rocks with fossils

17. Metamorphic rocks
Derived from meta-meaning change and morphic –meaning form.
Formed due to extreme heat and pressure
Marble

18. Formation of Metamorphic rocks

19. Metamorphism
Regional metamorphism-caused by large scale earth movements like mountain building activity.
Thermal metamorphism caused by high temperature
Dynamic metamorphism-alteration caused by high pressure during Earth movements.

20. ROCK CYCLE

22. There is a continuous process of change within the three types of rocks.It may take millions of years for the change to become visible.
Molten magma may solidify and when they are exposed to weathering, they are broken down into smaller pieces or sediments.
These are carried away and deposited under water bodies to form sedimentary rocks.
These again may undergo change due to heat and pressure and form metamorphic rocks.

23. The rock cycle may not always form a set pattern.
Sedimentary rocks may melt and form igneous rocks and metamorphic rocks may form sedimentary rocks.
And so the rock cycle continues.