Like most celestial bodies the earth is spherical in shape. You also know that hot water and molten lava are expelled from the interior of the earth. This indicates that the temperature below the Earth's surface is very high. The deepest mining in the world is limited only to the depth of less than 5 kilometers. These activities can be explained by better understanding the interior of the Earth. As we know, the characteristics of the earth rarely retain a fixed shape. Its shape constantly changes. A group of exogenetic forces includes those that weaken and disintegrate rocks in their original location. The second group consists of indogenetic forces that remove disintegrated rocks from the highlands and deposit them in the lowlands. These two processes have been responsible for disintegrating the rocks and giving shape to the new geographical features. They are also partly responsible for soil formation, which is very important to us. In this lesson, we will study about the interior of the earth and the materials that make up the upper portion of the Earth's crust. You will also learn about weathering and its types, the grading process, and the importance and formation of soils.
Interior of the Earth
It is not possible to know the interior of the Earth by direct observations due to its large size and the changing nature of its internal composition. Through mining and drilling operations, we have been able to observe the interior of the earth directly only to a depth of a few kilometers. The rapid rise in temperature below the Earth's surface is primarily responsible for setting a limit for direct observation within the Earth. The temperature inside the earth is so high that it can even melt any tool used for drilling. This fact also restricts deep drilling, making it difficult to directly observe materials inside the earth.
Temperature
The increase in temperature with increasing depth is observed in mines and deep wells. These evidences, together with the molten lava that emerged from the interior of the earth, support that the temperature increases towards the center of the earth. Different observations show that the rate of temperature increase is not uniform from the surface to the center of the Earth. It is faster in some places than others. At first, this increase is at an average rate of 10 ° C for each 32 meter depth increase. At such a constant rate of temperature increase, at 10 km depth, the temperature will be approximately 3000 ° C and at 40 km depth it will be 12000 ° C. At this rate, the Earth's interior should be molten. However, this is not the case because rocks buried under the pressure of several kilometers thick overlapping rocks melt at higher temperatures than similar rocks on the surface. A basaltic lava rock that melts at 12,500C on the surface will melt at 14,000C at 32 km depth. The additional heat required for fusion is produced by radioactivity. It is the result of the decomposition of the atomic nuclei of minerals that emit radiant energy in the form of heat from rocks. . The behavior of seismic waves is other evidence of this phenomenon. They also confirm that the composition of the different layers is as variable as the rate of temperature change. While in the upper 100 km, the increase in temperature is 12 ° C per km, in the following 300 km it is 20 ° C per km but it is only 100 C per km below. Thus, the rate of temperature rise below the surface decreases toward the center. The core temperature is estimated to be somewhere between 3,000 ° C and 50,000 C. Such a high temperature within the earth may be due to chemical reactions under high pressure conditions and the decay of radioactive elements.
Pressure
The pressure also increases from the surface to the center of the earth due to the enormous weight of the overlapping rocks. Therefore, in deeper portions, the pressure is tremendously high. The pressure near the center is considered to be 3 to 4 million times the pressure of the atmosphere at sea level. At high temperatures, the material underneath will melt towards the central part of the earth. This material melted under conditions of tremendous pressure acquires the property of a solid and is probably in a plastic state.
Density
Due to the pressure towards the centers of the earth and the presence of heavy materials, the density of the earth's layers also increases. Apparently the material of the interior of the earth is very ga ense which has already been said.
The subject of the Tragedy of the Earth
The outer part of the lithosphere is called the crust. This is the most significant part of the earth because it has been occupied by humans. The material of the crust is made of rocks. There are different types of rocks. They are hardest like granites, soft like clay and loose like gravel. Rocks vary in color, weight, and hardness. Rocks are made of minerals. It is an aggregate or physical mixture of one or more minerals. Minerals, on the other hand, are made up of two or more elements in a certain ratio. They have a specific chemical composition. The crust is made up of more than 2000 minerals, but 6 of them are the most abundant and contribute the most to this upper part of the earth. These are feldspar, quartz, pyroxene, amphiboles, mica and olivine. Granite is a rock and its constituent minerals are bound together by quartz, feldspar and mica which make it a hard rock. Changes in the ratio of these minerals give rise to granites of different colors and hardness. Minerals containing metals are called metallic minerals. Hematite, a major iron ore metallic mineral. Ores is a metallic mineral whose profit can be made. Rocks are of great economic importance to us.
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