The rocks

Get to know about the types of rocks .

Transcript

2. Rocks are made up different minerals. Minerals are naturally occurring substances which have certain physical properties and definite chemical composition . Ex- petroleum , coal, natural gas . The basic unit of which earth is composed.
3. The earth’s crust has rocks . Any natural mass of mineral matter that makes up a earth’s crust is called rock. The earth’s curst is made up of various types of rocks, colour, mode of occurrence , degree of resistence , rocks also form a basis for soil,determine natural vegetation, etc. There are basically three types of rocks. •Igneous •Sedimentary •metamorphic
4. Magma Igneous rocks sediments Sedimentary rocks Metamorphic rocks Weathering & erosion Heat and pressure Cooling & melting Heat & pressure composition
5. Formed by the cooling and sodification of molten rock( magma) Crystalline in structure High proportion of silia then called acid. (granite is less dense than basic rocks). Also called primary rocks. There are two types of igneous rocks • Intrusive /Plutonic rocks- when the molten magma cools down deep inside the earth’s crust . They cool down slowly and then form large grains, formed at some dept , easily recognized, ex- granite, diorite. • Volcanic/ extrensive- molten magma coming from interior of earth as a lava. They have fine granite structure, ex- basalt
6. Derived from a Latin word sediments which means setting. They can easily broken ,different from others in layer formation, non-crystalline , contain fossils, classified to their age. Rocks roll down , hit each other than broke into smaller fragments called sediments . Then transported and deposited by winds, water. Then are compressed and hardened and forms . Classified as:- •Mechanically formed -sandstone are made from sand grains, used for building/ grindstone. A coarser type of sandstone is called grit. Larger pebbles cemented to form a rock is called conglomerate. Finer sedimentary material form clay , used for brick-making , shale/ mudstone. •Organically formed –formed from the remains of living organisms , ex- calcareous, including limestone and chalk, coal. •Chemically formed- precipited chemically from solutions , rock salts derived from beds of seas/lakes, gypsum /calcium sulphate from evaporation of salt lakes , potash, nitrates.
7. Igneous or sedimentary may became metamorphic / changed rocks under great pressure and heat. Clay may be metamorphosed into slate, limestone to marble, sandstone to quartzite, granite to gneiss, shale to schist, coal to graphite. It is a process by which already consolidated rocks undergo recyatrallisation . Occurs when rocks are forced down to lower levels by tectonic pressure.
8. •2000 minerals have been named and identified in the earth’ s crust. •The basic source of all minerals is the hot magma in the entire earth. •A rock has combination of different minerals. •Feldspear and quartz are most common minerals formed . •Petrology is the science of rocks.