definition of earth's crust

The most superficial layer of planet earth is known as the earth's crust, its thickness varies from 5 km, at the ocean floor and 40 km, in the mountains. Among the most characteristic elements that make up this structure are silicon, oxygen, aluminum and magnesium. Meanwhile, in this, in turn, three layers are distinguished: sedimentary, granitic and basaltic. On the sedimentary side, it is composed of sedimentary rocks that are found only on the continents and on those bottoms close to the continent.

In the case of granite, those that compose it are rocks similar to granite that will form the mother mass of those emerged continental areas. Between this layer and the next one is located the Conrad discontinuity, which indicates the limits between the granite and the basalt and finally, the basalt, is made up of rocks similar to the basalts, this is the layer immediately continues to the earth and the Mohorovicic discontinuity separates it from the mantle.

The earth's crust is divided into two types, the oceanic and the continental. The oceanic represents 75% of the surface of the planet earth, it is much finer than the continental one and in it three levels are recognized. The lowest level or level III is made up of gabbros, basic plutonic rocks, and borders the mantle of the Mohorovicic discontinuity. On these rocks level II of basalt rocks is erected, with the same composition as the previous one, then a lower area composed of dikes extends and the most superficial area of ​​this level is made up of padded basalts, which were formed as a result of the solidification of lava with ocean water. And on the basalts, then level I will be erected, formed by sediments.

And the continental one has a less homogeneous and dense nature than the previous one, that is why it is located above the oceanic one, since its composition includes rocks that come from different origins, such as acid igneous like granite, accompanied by an important mass of metamorphic rocks.

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