gh FRICTION INSIDE THE EARTH IS A SOURCE OF HEAT

There is high temperature inside our planet and the reason is not known yet. A common belief that the Earth's interior is heated by radioactive elements is now doubted of. Professor Felix Letnikov from Irkutsk Institute of the Earth's Crust have proposed an idea that the heat is formed in the outer core because of friction between its layers.

Different geophysical data confirm that there is a heat source inside the Earth. In the mantle there are zones with low viscosity, which correspond to molten substance. However, melting rocks requires a lot of energy - so, the question about a source of the energy arises. According to current information, the core consists of two parts: a liquid outer part and a solid inner part. The outer core begins at the depth of 2900 km and is 2346 km thick; it holds 31% of the Earth's mass. It is pressed between the inner core and the mantle, and because of the Earth's axial rotation there is friction and heat formation between these two matters. Still, that is not the main heat source. In the outer core at different depths there are different temperature, pressure, viscosity and density, and this results in stratification. Try to spin a tin with condensed milk stored for some time on a shelf. Inside the milk, layers will rub against each other and the tin's sides. And the fact that friction causes heat is well-known.

According to Letnikov's theory, heat explosions happen because sometimes heat does not go away to the mantle. In such situation the core contents is of a big role. It includes iron with some nickel and many gases - hydrogen, sulphur and carbon. When explosion happens, a part of the gases mixture detaches and flows away into the mantle. This process is thought to be the cause of most of the abyssal processes.

For millions of years gas streams travel through the mantle to the crust. It takes a lot of energy from the stream and some of them never reach the surface. However, those who succeeded in getting outside cause different troubles, like eruptions, lava flows and earthquakes. Moreover, the stream's heat loss may be recovered by chemical reactions: the stream contains much hydrogen and 80% of the mantle volume is taken by oxygen. The result of the reaction is water and heat. In addition, such streams carry many rare elements, therefore, producing large areas of minerals.

Until the Earth has the liquid core, the heat flow is guaranteed, but geologists say that, with time, abyssal processes are gradually dying down.

***