La oceanic crust It is the part of the Earth's crust that is covered by the ocean. That's two-thirds the size of Earth's surface, but it's less explored than the moon's surface. Along with the continental crust, the oceanic crust separates the Earth's surface from the mantle, the inner layer of the planet that contains hot and sticky material. However, these two cortices differ significantly from each other.
In this article we are going to tell you everything you need to know about the oceanic crust, its origin and characteristics.
Structure of the oceanic crust
The average thickness of the oceanic crust is 7.000 meters, while the average thickness of the continental crust is 35.000 meters. In addition, the oceanic plates are much younger: they are estimated to be about 180 million years old, compared to 3.500 billion years for the continental plates.
In ancient times, people believed that the bottom of the sea was a great plain. However, over the years, science has been able to determine that oceanic crust also has landforms, just like continental crust.
At the bottom of the ocean you can find mountains, volcanoes and trenches. In addition, in some cases, strong earthquakes and volcanic activity can be felt even on the mainland. This is related to the study of earthquakes that affect the Earth's crust and its relationship with edge of tectonic plates. In addition, oceanic crust has unique characteristics that set it apart.
Continental margins and slopes
Although the oceanic crust is thought to be the part of the earth's crust that is covered by the ocean, it is worth considering that it does not exactly start at the coast. In fact, the first meters behind the coast are also continental crust. The true starting point of the oceanic crust is located on a steep slope a few meters or kilometers from the coast. These slopes are called slopes and can be as deep as 4.000 meters.
The space between the shore and the slope is called the continental margin. The depths of these waters do not exceed 200 meters, and they contain the greatest variety of marine life. This aspect of the margin is related to the study of the continental crust which also affects marine fauna. Furthermore, it's important to note that the environment and its relationship with the ocean are fascinating aspects to study.
mid-ocean ridge
Ridges are ridges on the seafloor that form when magma from the mantle rises toward the crust and breaks it. Over the centuries, this movement it has managed to form mountains that extend over 80.000 kilometers.
The tops of these mountains are fissured, and magma is constantly flowing from the mantle. Due to this, the oceanic crust is constantly renewed, which explains why it is much younger than the continental crust.
As a result of this constant volcanic activity, the ridges grow out of the sea, forming formations such as Easter Island on the East Pacific Ridge and the Galapagos Islands on the Chilean Mid-Ocean Ridge. To learn more about these formations, you can consult the article on the mid-ocean ridge, in addition to exploring its relationship with the volcanism in the region.
nether plains
The abyssal plain is the flat area between the continental slope and the mid-ocean ridge. Its depth varies between 3.000 and 5.000 meters. They are covered by a layer of continental crustal sediment that completely covers the ground. Thus, all geographic features are hidden, giving a completely flat appearance.
At these depths, due to the distance from the sun, the water is cold and the environment dark. These characteristics did not prevent life from developing on the plains; however, the specimens found in these areas had very different physical characteristics than those found in other seas. This poses an interesting contrast with the characteristics of the oceanic crust and its origin, and its relationship with the ocean trenches.
Guyots of oceanic crust
Guyots are tree-trunked mountains whose tops have been flattened. They are located in the middle of the abyssal plain and can reach a height of 3.000 meters and a diameter of 10.000 meters.. Their peculiar shape emerges when they reach a sufficiently high surface and the waves slowly erode them until they become a flat surface. The waves have even worn away the tops of mountains so much that they are sometimes submerged 200 meters below the surface. This phenomenon is directly related to the process of formation of volcanic islands and erosion.
marine or abyssal trenches
Abyssal trenches are narrow, deep fissures in the seafloor, up to several kilometers deep. They are created by the collision of two tectonic plates, which is why they are usually accompanied by a lot of volcanic and seismic activity, which can cause huge tidal waves, which are sometimes felt on the continents. In fact, most trenches are located near the continental crust because they are created by the collision of oceanic and continental plates.
Especially on the western edge of the Pacific Ocean, the deepest trench on earth: the Mariana Trench, which is more than 11.000 meters deep. This aspect of ocean trenches is crucial to understanding how they are generated and their impact on the environment, as well as their relationship with the phenomenon of the structure of the earth and continental drift.
Underwater scientific exploration in the oceanic crust
Throughout history, the oceanic crust has been one of humanity's greatest mysteries, due to the difficulty of diving into the cold, dark depths of the ocean. That's why science is hard at work designing new systems to better understand the geography of the seafloor and how it originated.
The first attempts to understand the seabed were rudimentary: from 1972 to 1976, scientists aboard HMS Challenger used a rope 400 meters long to submerge it in the ocean and measure its bottom point.
In this way, they can learn about depth, but the process must be repeated at different locations to map the seafloor. Of course, the activity is expensive and exhausting. However, this seemingly primitive technology has allowed people to discover the deepest place on the entire surface of the earth - the Mariana Trench.
Today, more sophisticated methods exist. For example, scientists at Brown University were able to explain volcanic activity at mid-ocean ridges by studying earthquakes in the Gulf of California.
This study and other research supported by scientific tools such as seismographs and sonars are leading to a growing understanding of the mysteries of the deep ocean., even if it is impossible to plunge into it.
