TYPES AND CHARACTERISTIC OF ROCKS

During volcanic eruptions,magma spurts out of the Earth's surface as lava

Lava cools rapidly and crystallises into fine-grained such as:

basalt

pumice

obsidian

Magma that is trapped deeper in the crust will cool slowly and crystallise into coarse-grained igneous rocks such as

granite

gabro

diorite

Characteristic

hard

shiny

have crystallised structures

have no layers

contain no fossils

Example of igneous

granite

pumice

Are formed either igneous rocks or sedimentary rocks that undergo chemical changes due to very high pressure and temperature

Characteristic

Shiny

Some contain crystal such as schist

Harder and denser than their parent rocks

Some have layers like gneiss and slate

Some have no layers like marble

Examples of metamorphic rocks

marble

gneiss

Are weathered and eroded by wind,rain,waves,ice and heat from the Sun to form fragments of sediments

The fragments of sediments are transported by streams and deposited with mud,silt,sand,animal shells and fossils on the seabed

Characteristic

have layers

Often contain fossils

Have no crystallised structures

Have dull surfaces

Softer and more brittle than igneous rocks

Examples of sedimentary rocks

Limestone

Sandstone

Shale

Conglomerate

Gypsum

Coal