- The Rock Cycle -

There are 3 rock types

-Igneous

-Sedimentry

-Metamorphic

Rocks which are formed from the cooling and soldifying of magma, are said to be IGNEOUS.

-This cooling may take place quickly on the Earths surface, such as in a volcano, which case the rock is said to be EXTRUSIVE BASALT.

-The colling can take place slowly inside the Earths crust, in which case the rock is said to be INTRUSIVE GRANITE.

-These rocks usually contain randomly arranges interlocking CRYSTALS and are usually VERY HARD.

Sedimentry.

Some rocks are formed when layers of small particles collect on the sea bed and have the WATER squeezed out of them. The particles become cemented together by mineral salts.

-These rocks are sedimentry

-They are GRAINY AND CRUMBLY

-Example is sandstone.

Metamorphic

-Mountain bulding processes often force rocks deep underground close to magma, where they are subjected to EXTREAMLY HIGH tempretures and PRESSURE, causing their structure to change without melting 

-These rocks are usually very hard and contain crystals often in bands.

-An example is Marble, which is formed through limestone.