ROCKS

Presented ByMD NURUDDINSURVI SONLB.TECH(BIOTECH)SHARDA UNIVERSITY

What are Rocks?A rock is a naturally

occurring solid mixture of one or more minerals, or organic matter

Rocks are classified by how they are formed, their composition, and texture

Rocks change over time through the rock cycle

Igneous RocksIgneous rock begins as magma.Igneous rock is formed through the cooling

and solidification of magma or lava.Magma freezes between

700 °C and 1,250 °CMagma is a mixture of

many minerals

Extrusive and Intrusive rocksAt the surface, lava hardens to form

extrusive rocks with tiny crystals or glassy texture.

Beneath the surface, magma hardens to form intrusive rocks with easily visible crystal texture.

Sedimentary Rocks Sedimentary rocks form when

sediments harden into rocksThree Types:1. Clastic: formed from

fragments of other rocks.2. Chemical: formed from

mineral grains that come out of solution.

3. Organic: formed from the remains of plants/animals.

Metamorphic Rock Meaning to change shape

Metamorphic rocks “morph” (change) from existing rock, due to heat, pressure and chemicals.

Usually takes place deep in

the Earth

Types of metamorphismRegional Metamorphism: large areas of

rock are under intense heat/pressure, which occurs during mountain-building.

Contact Metamorphism: when hot magma forces itself into overlying rock (intrusions) and bakes the rock

Metamorphic RockFoliated - contain aligned grains of flat

minerals

Gneiss is foliated metamorphic rock that has a banded appearance and is made up of granular mineral s.

Metamorphic RockNon-Foliated – mineral grains are not

arranged in plains or bands

Marble is a non-foliated metamorphic rock that is produced from the metamorphism of limestone.

THE ROCK CYCLEThe three types of rocks are very closely

related:Igneous rocks are attacked by erosion and

weathering to form sedimentsCrustal movements can cause deep rocks

to reach high temperatures and to melt back into magma

Igneous and sedimentary rocks exposed to intense heat and pressure can become metamorphic