Types of Rocks

Types of rocks

Done by Alyazia ahmad alsuwaidi

A rock is made of grains that fit together. Each grain in the rock is made from a mineral, which is a chemical compound. The grains in a rock can be different colors, shapes and sizes.

Some types of rock have interlocking grains that fit tightly together. Granite is a rock with interlocking grains. Other types of rock have rounded grains. Sandstone is a rock with rounded grains.

What are rocks?

Granite has interlocking grains

Sandstone has rounded grains

Rocks with rounded grains are more likely to absorb water than rocks with interlocking grains. This is because the water can get into the gaps between the grains. Rocks that absorb water are called porous. Rocks with rounded grains are usually softer and more crumbly than rocks with interlocking grains.

What are rocks?

Rocks with rounded grains are more likely to be crumbly and

porous

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Rocks with interlocking grains are more likely to be hard and non-porous

The rock cycleThere are three main types of rock:

- Sedimentary, for example chalk, limestone, sandstone and shale;

- Igneous, for example basalt and granite;

- Metamorphic, for example slate and marble

The Earth's rocks do not stay the same forever. They are continually changing because of processes such as

weathering and large earth movements. The rocks are gradually recycled over millions of years. This is called the

rock cycle.

Sedimentary rocks • Formation

• For millions of years, little pieces of our earth have been eroded by wind and water.

• These little bits of our earth are washed downstream where they settle to the bottom of the rivers, lakes, and oceans.

• Layer after layer of eroded earth is deposited on top of each. These layers are pressed down more and more through time(compaction and cementation), until the bottom layers slowly turn into rock.

Formation

The inside of the Earth is very hot - hot enough to melt rocks. Molten )liquid( rock forms when rocks melt. The molten rock is called magma. When the magma cools and solidifies, a type of rock called igneous rock forms.

Igneous rocks

Metamorphic rocks Formation

Earth movements may cause rocks to be deeply buried or squeezed.

As a result, the rocks are heated and put under great pressure. They do not melt, but the minerals they contain are changed chemically, forming metamorphic rocks. Sometimes, metamorphic rocks are formed when rocks are close to some molten magma, and so get heated up.