We know from the very basic principles of geology that the internal structure of the earth has four layers. Crust, mantle, outer core and outer core, and inner core. These layers are arranged like onions.

Researchers at the Australian National University recently found another fifth layer inside the inner core. Understanding this level, they say, will make it possible to better understand the Earth's internal structure, its history, and its evolution.

The earth was formed about 4.6 billion years ago. It started with the formation of its rocky center. It is

formed by the collision of heavy elements. This center is divided into two levels. The outer layer is mainly made of liquid iron-alloy metal. Its thickness is about 1,355 miles. The inner center is about half its thickness, about 60 miles. This part is also made of iron alloy. But here iron is not liquid, it is hard. In fact, although the heat in the outer center is impossibly high, the pressure is not so high. So the iron melts here. In the inner center, the heat, as well as the pressure, is much higher. This pressure prevents the iron from melting. This inner core is thought to be responsible for the Earth's magnetic field.

There is a mantle above the center. In Bengali, it is called a land cover. This part is formed mainly from magnesium and iron-rich silicate rocks. Its thickness is about 1,793 miles. It has a crust on it. Its thickness varies from 16.8 to 43.5 miles depending on the place.

Scientists have long suspected that the inner core may be divided into multiple layers. But so far there was no evidence in favor of it. Researchers at the Australian National University have recently found evidence of this. By analyzing data from seismograph stations located in different parts of the world, scientists were studying how fast seismic waves travel through different layers of the earth. This information has come out from that study. This layer is called 'Innermost Inner Core'.