Interesting Facts About The Earth's Crust: Earth Science For Kids!

When we mention a crust, not the pizza crust but the Earth's crust, we are talking about the outermost layer of the Earth.

For geologists, the term 'crust' is linked to the outermost surface of any planet. It can also indicate celestial bodies. But, in the case of Earth, there is a slight diversion from the traditional concept, and it indicates the layer which supports life!

Almost 70% of the Earth's crust is formed by the continental section, while oceanic crusts only account for 30%. The mountainous regions, like the Andes (South America) or the Himalayas (India), have the thickest layer of the crust due to crustal thickening and prolonged plate collision.

The concept of plate tectonics and the Earth's crust formation or structuring is intricately related. Do you know how scientists measure the movement of these dynamic plates? Satellites!

At present, there are almost 25 of these keeping an eye on these plates to study more about their movement. Even the speed of these plates vary.

While the Eurasian plate is the slowest, do you know the name of the fastest plate? It is the cocos plate! These areas with tectonic instability are the natural zones of earthquake or vulcanism.

Want to know more about Earth's crust facts? Read on to find some mind-blowing facts!

If you would like to read some more fun facts, then you can read the pieces on facts about the body system or facts about mercury.

Role Of The Earth's Crust

The outermost layer of the Earth, the crust, plays an essential role in providing essential minerals and sustaining various life forms.

Did you know that our planet Earth is not the only planet that has a crust? There are other planets with a thick crust, like Mercury or Mars.

But it is the only planet where the crust has a vital role to play. The surface of the Earth is home to numerous rock varieties, minerals, which are of economic significance.

This collection of different rocks give rise to picturesque landforms and adds value to diversity. The crust is the zone of mountain-building processes and other evolving landforms. It can support life forms, be it the human population or wild flora and fauna.

The crust supports forests, which are a rich source of wood, fuel, and timber. It is also a home for the rich diversity of flora and fauna.

Flora is an enhancing factor of beauty to the Earth, which survives on the crust. The Earth's crust is made up of nutrient-rich soil on which every human being is dependent.

Formation Of Earth's Crust

One of the crucial Earth's crust facts is its formation, which took place approximately 4.6 billion years ago. The Earth's crust is made up of minerals and rocks and is susceptible to the movement of plates.

At present, three theories explain the formation of crust: the accretion model, the impact model, and the terrestrial model. The last one, however, is considered to be the aptest explanation.

It explains that the internal processes of the Earth are responsible for its formation. This can be traced back to billions of years ago when it was simply a hot ball of rock.

It was built of nickel and iron, which later became core on sinking. Approximately 4.6 billion years ago, the other two layers, crust, and mantle came to being when the Earth's surface gradually cooled. After cooling, it hardened to form the thinnest layer, the crust.

Owing to plate tectonics, the crust was transformed many times. But apart from the tectonic plates, even the asteroids are responsible for modifying the crust.

The Earth's lithosphere (which is segregated into small fragments called tectonic plates) is formed by the upper mantle, and the crust is built up of 15 tectonic plates. The Earth's crust result from the accumulation of basalt lava flows from vulcanicity over the years.

After its formation, the Earth's crust was divided into two categories, namely the continental crust and the oceanic crust. The oceanic crust is quite younger if compared to the continental crust, mainly due to the subduction process.

Along the mid-ocean ridges, the oceanic crust gets recycled! In these zones, two plates move towards each other.

The Earth's continental crust was formed about 2 billion years ago, while the oldest oceanic crust is only 200 million years old! The continental crust is lighter and thicker than the oceanic crust.

As a result, the thicker and lighter continental crust always floats on the heavier and thinner oceanic crust. Earlier, these oceanic crusts were almost 12 mi (20 km) thick, which later reduced with decreasing Earth temperature.

The ocean floor is made up of the basaltic layer. These crusts get carried in the form of plates and can carry both continental crust and oceanic crust.

Parts Of Earth's Crust With Temperature

The two important parts of the Earth's crust are the continental crust and the oceanic crust. The Earth itself has two other important layers, mantle, and core segregated based on temperature and density.

The crust, which is the outermost layer of the Earth, can be distinguished into continental crust and its counterpart, the oceanic crust. The continental crust is considered to be synonymous with the 'sial' layer, while the oceanic crust is thought to be in tune with the 'sima' layer.

The difference between the oceanic crust and continental crust is based on their composition.

The former is built of mafic rocks rich in magnesium and iron, while the latter is built of igneous rocks, sedimentary rocks, and metamorphic rocks. These are rich in aluminum silicates.

But, did you know that the Earth also has two other important layers which have temperature and density differences? The Earth's interior is extremely hot, so much that a part of it is liquid rock! You can read about all three layers in detail here.

Crust: Among all the Earth's layers, the crust is the thinnest and is only about 43 mi (70 km) in depth. Do you know that it is the only layer that can be studied via drilling?

The Earth's crust is again broken into movable plates. These plates seem to float on the molten rock layer beneath it, the mantle. Among all the other layers, the Earth's crust is also the coolest, which is the same as the ambient air temperature.

However, the temperature of this crust increases is directly proportional to depth and increases as we move downwards. In the upper crust, the temperature reduces at an exceptional rate of 10 °C (50 °F) per km!

Mantle: The mantle is the second layer and the thickest, which extends for almost 1795 mi (2890 km)! The upper part of the mantle or upper mantle is viscous where the silicates are in a solid-state, but there are local molten areas, too, making it semi-solid in nature.

The lower part of the mantle or the lower mantle is less viscous due to the tremendous overlying pressure.

In the mantle, the temperature varies from 1000 °C (1832 °F) at the uppermost boundary with crust to 3700 °C (6692 °F) at its lower boundary with the core. Do you know that this makes the average temperature of the mantle at least three times greater than the planet Mercury?

Core: The core is the innermost layer of the Earth and has two segregations: the outer core, which is solid, and the inner core, which is 'liquid.'

The temperature at the former is estimated to be between 2730 °C (4940 °F) and 4230 °C (7640 °F), while the range for latter is 3730 °C (6740 °F) and 7730 °C (13940 °F).

Minerals Of Earth's Crust

The Earth's crust, which is the outermost layer of the Earth, is a hub of minerals. Almost 98.5% of the crust of the Earth is formed by unique chemical elements like iron, oxygen, calcium, sodium, potassium, silicon, aluminum, and magnesium.

The crust of the Earth is the only layer where drilling is possible for the extraction of rocks and different types of minerals. This crust is made up of eight important minerals, namely iron, magnesium, silicon, oxygen, calcium, sodium, potassium, and aluminum.

Titanium, carbon, sulfur, etc., make up for the rest. These minerals aggregate to form various rocks which dominate the crust.

The crust is made up of rocks that belong to the group of igneous, metamorphic, and sedimentary rocks. Igneous rock is formed when magma gets hardened inside the Earth after cooling.

For instance, Basalt or granite is such a volcanic rock. Sedimentary rock is formed by the accumulation of different types of sediments, including dead animals and flora, over the years, while dynamic changes form a metamorphic rock from the other two.

Chalk is a classic example of sedimentary rocks, while marble is a metamorphic one. There is also the basaltic layer of the oceanic crust which forms the ocean floor.

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