Then the problem is coming. Maria Trench swallows seawater every year. Why does the sea level rise instead of falling? Today, we will talk about this problem.
Water cycle in nature
First of all, we want to emphasize that "the Mariana Trench devours seawater" is not a strange thing in itself. On the contrary, it is actually a very common thing, which is accompanied by the development history of the whole earth. This should start with the water cycle of the earth.
The water cycle actually means that water absorbs energy from the sun through different parts of the earth to change its way of existence, and then it is sent to another part of the earth.
The water cycle of the earth ensures the dynamic balance of the total water resources on a large scale. Now we also know that due to global warming, some ice sheets and glaciers melt, so that the sea level rises. However, sea level rise will actually bring a lot of harm, such as: some coastal cities are flooded and island countries and low-lying countries disappear. Countries that may be submerged in the future are:
Bangladesh, Papua New Guinea, Philippines, Barbados, Kiribati, Egypt, Tuvalu and Maldives.
However, in fact, we are basically thinking based on the surface of the earth, and we have not gone deep into the interior of the earth. In fact, there is a system similar to the "water cycle" inside the earth. This is what we are going to talk about today.
The sea was swallowed up?
In fact, it can be simply said from the formation of the earth. 4.6 billion years ago, the solar system was gradually formed under the gravitational collapse of a molecular cloud.
In fact, the temperature of the earth was very high when it was formed. There is a lot of water in the atmosphere in the form of water vapor, but due to gravity, water vapor does not escape. Later, as the earth cooled slowly, water vapor fell in the form of liquid water, and there was a rainstorm on the earth that lasted for millions or even millions of years. Then, some asteroids and meteorites in the solar system also brought some water. These two parts of water are actually the composition of the primitive ocean.
At the earliest time, the mainland was not like this, but there was a whole pan-continent, and the primitive oceans were also connected together, called pan-ocean. So why did the mainland become like this?
We can think about it, what is the biggest difference between the primitive ocean and the modern ocean? To put it bluntly, "pit" is different. There used to be only a whole "pit", but now there are actually many more "pits".
Scientists discovered a problem through careful exploration and research. The age of the "pit" of the modern ocean is no more than 220 million years. We know that the primitive ocean appeared shortly after the formation of the earth, at least for more than 4 billion years. This shows that drastic geological changes took place on the earth 220 million years ago, which led to the division of Pan-continent.
Scientists have also made various researches and explorations on the changing process of this period. At present, the most mainstream theory is the plate drift theory.
To understand this theory, we must first have a simple understanding of the structure of the earth.
Below the surface is the crust, and below the crust is the mantle. But it is also the crust, and there are differences. Generally speaking, we can be divided into oceanic crust and continental crust. Among them, the ocean crust is very thin and heavy. On the contrary, the continental crust is thick but light.
Below the crust is the mantle, which is actually divided into the upper mantle and the lower mantle, but this is not the point. The point is that the mantle temperature is very high and thick. Under the action of thermal convection, the mantle will flow, and the ocean plate will grow and move with it during the flow.
But as mentioned above, the ocean crust is thinner and heavier than the continental crust, so the ocean crust will actually dive downward under the action of gravity.
Because the ocean crust is heavier than the continental crust, it is also thinner. As a result, the ocean crust began to dive downward. In the process of subduction, a lot of water will flow into the earth. So will this water disappear?
Not really. Scientists found water in the crater, which actually entered the earth's interior, and then returned to the earth's surface with magma, participating in the earth's water circulation system, which ensured that the overall water on the earth's surface would not be missing too much.
Therefore, in fact, the sea level will not fall because the Mariana Trench devours seawater.
The "new pit" of our current ocean is actually formed slowly through this form, and the culprit is actually crustal movement.
Thus, from 220 million years ago, with the movement of the earth's crust, the earth's oceans gradually evolved from vast oceans to modern oceans.