Characteristics of the CONTINENTAL CRUST

Our planet is made up of different layers of different composition, structure and characteristics. From the interior to the terrestrial exterior we differentiate a core, a mantle and a terrestrial crust. In turn, in the earth's crust we have an oceanic and a continental crust. In this lesson of a teacher we will review the characteristics of the continental crust. If you want to find out more about her, we will tell you about them in this article!

Index

1. What is the earth's crust and its characteristics
2. What are the characteristics of the continental crust
3. structure of the continental crust

Before talking about the characteristics of the continental crust, we are going to know what the earth's crust is in order to better understand this concept.

The Earth crust has a 40 km extension and is divided into:

• oceanic crust. The oceanic crust is the part that forms the oceans.
• continental crust. The continental is what forms the continents.

However, there is a part of the continental crust in the coastal zone and that forms the so-called Continental platform. This is an area of ​​great economic interest for the countries, since it contains the largest quantities of flora and fauna, large reserves of minerals and fossil fuels such as oil and gas natural.

Characteristics of the earth's crust

• The earth's crust is not the layer that occupies the most on earth, because it only represents 1% of the mass this.
• Its boundary with the Earth's mantle is marked by the so-called Mohorovicic discontinuity.
• The thickness of the earth's crust is not the same throughout its length, but varies depending on the area. Thus, in its terrestrial part it varies from 30 to 70 km thick, while in its oceanic part it only reaches 10 km thick.
• It is the most heterogeneous layer of the planet earth, since in the continental areas it is subject to great changes that produce different geological agents or the various elements of the climate, which build or destroy the relief of the areas continental.
• The upper part of the continental crust is mostly granitic in nature, while its lower part is mostly basaltic. However, the oceanic crust does not have a granitic layer and its age and density is lower.

Image: Geology.net

We are going to know the characteristics of the continental crust. As we have already seen, the continental crust is the most complex and thickest of the earth's crust. In it are also the slopes and the continental shelf. Vertically, it can be divided into sedimentary, granitic and basaltic layers. The characteristics of each one are the following:

• sedimentary layer: the sedimentary layer is the upper layer of the continental crust and is quite folded. It is a variable layer, because in some areas of the earth it is not present, while in other areas it exceeds 3 km in thickness. Its density is approximately 2.5 g/cm³
• granitic layer: in this layer there are a large number of metamorphic rocks such as the so-called gneisses and mica esquitos. The thickness of this layer is between 10 and 15 km and its density is about 2.7 g/cm³.
• basalt layer: this layer is the deepest of the continental crust and its thickness is between 10 and 20 km. Its density is the highest of the three and is from 2.8 g/cm³. Its composition contains igneous rocks such as gabbros and metamorphic rocks such as amphibolites. Between both granitic and basaltic layers is the so-called Conrad discontinuity and in this area there may be a sudden contact between both layers that can be observed during earthquakes by the presence of longitudinal waves or P waves and transverse waves or s.

Now that we have seen and known the characteristics of the continental crust, we are going to know its structure. And it is that, usually, divides the earth's surface into two zones main structural:

Cratons

They are more rigid and stable areas of the earth's surface and have remained so for millions of years. They are areas without great reliefs and which in turn are divided into shields and platforms.

1. Shields: are the areas that occupy most of the continents. Due to the shields, there are large mountain ranges that have been shaped by erosion and other external agents over thousands of years. In these areas the sediment layer is completely lost. Rocks are deposited on its surface, but they are not the ones that formed the primitive mountains. The original mountains have been formed by great pressures and temperatures, so they are metamorphosed.
2. platforms: These are areas of cratons that still retain their sediment layer, which is slightly folded.

orogenic mountain ranges

Orogenic ridges are located at the edges of cratons. They are areas of the continental crust that have been subjected to deformation processes due to the movement and displacement of tectonic plates over the years. In the mountain ranges, the crust reaches its maximum thickness, up to 70 km. The modern mountain ranges are located on the edges of the Pacific Ocean.

Image: Sciencesphere

If you want to read more articles similar to Characteristics of the continental crust, we recommend that you enter our category of geology.

• Agüera-Àngel, C. When and how the continental crust was created: When the present is not the key to the past.
• Agüera Àngel, C. (2014). Origin and evolution of the continental crust.