TYPES AND CHARACTERISTIC OF ROCKS

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Historical Perspectives

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rocks

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Classifying Metamorphic Rocks

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Three mian rocks

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TYPES AND CHARACTERISTIC OF ROCKS

SEDIMENTARY ROCKS

Examples of sedimentary rocks

Coal

Gypsum

Conglomerate

Shale

Sandstone

Limestone

Softer and more brittle than igneous rocks

Have dull surfaces

Have no crystallised structures

Often contain fossils

have layers

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

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

METAMORPHIC ROCKS

Examples of metamorphic rocks

gneiss

marble

Some have no layers like marble

Some have layers like gneiss and slate

Harder and denser than their parent rocks

Some contain crystal such as schist

Shiny

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

IGNEOUS ROCKS

Example of igneous

Characteristic

contain no fossils

have no layers

have crystallised structures

shiny

hard

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

diorite

gabro

granite

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

obsidian

pumice

basalt

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