Rock formation

The way that rocks are formed is associated with their type, which can be classified as magmatic or igneous, metamorphic and sedimentary.

The lithosphere is an upper and solid layer of the Earth, made up of rocks , which are formed by the junction of different minerals.

They order the earth’s crust, the outer layer of the planet, while in the lower layers, with the exception of the inner core, the rocks are arranged in liquid form, called magna.

However, according to the dynamic nature of the surface, through the processes of erosion , weathering , tectonism , among others, the rocks are classified.

There are three types considered main: magmatic or igneous rocks, metamorphic rocks and sedimentary rocks.

In this way, explaining their origin is associated with their types. Check the rock formation process below .

Index hide ]

  • Formation of magmatic or igneous rocks
  • Formation of metamorphic rocks
  • Formation of sedimentary rocks

Formation of magmatic or igneous rocks

The magmatic rocks , also called igneous are formed from the magma solidification.

The process takes place inside the earth’s crust or even when the lava goes outside the mantle, through the volcanic eruption.

When it is internal, it occurs more slowly and gradually, conceiving the rocks classified as intrusive, as is the case with granite.

Magmatic rocks – granite

However, when it develops through volcanic eruptions, solidification is faster and conceives rocks classified as extrusive, such as basalt.

Magmatic rocks – basalt

Formation of metamorphic rocks

The metamorphic rocks formed by the other rocks, but by a diverse process.

In the case in question, the magmatic or igneous rocks, the sedimentary rocks or even the metamorphic ones are subject to high levels of temperature and pressure inside the crust.

Therefore, there is a metamorphosis, that is, the original characteristics are modified, as well as the chemical structure, which ends up conceiving another rock.

Marble, made from limestone, and gneiss, the result of granite, are examples of metamorphic rocks.

Metamorphic rocks – gneiss

Therefore, rocks do not have only one formation process. They are constantly changing, through the cycle of rocks .


Weathering is essential in the rock cycle, since it breaks down rocks with the help of water, heat, wind and even living things.

There are three types of weathering:

  1. Chemical weathering: Decomposition of rocks caused by water linked to high temperatures and acids from organic matter.
  2. Physical weathering: Breaking of rocks due to temperature fluctuation, as well as frozen water in its cracks and the crystallization of salts, which modify its chemical structure.
  3. Biological weathering: Disintegration of rocks caused by the action of bacteria, fungi, plants and humans.

Formation of sedimentary rocks

The sedimentary rocks are formed from particles of other rocks, loaded by water, wind or gravity, leave in the lower regions of the relief.

The fragments are enveloped by others in the process that lasts for thousands of years, being called sedimentation. Faced with the pressure of the layers above, the sediments compact and become clusters of rocks.

In summary, sedimentary rocks are stratified, which means that they are formed in layers. The layers and the different types of sediments indicate the period in which they were deposited on the site, the fact that the more superficial the more recent it is.

The constitution of sedimentary rocks benefits the preservation of fossils that, even, are only found in sedimentary rocks. Another wealth found in sedimentary basins is oil , a mineral resource of extreme relevance to society.

Some examples of sedimentary rocks are slate, sandstone, clay and limestone.


by Abdullah Sam
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