What do you Understand by Homeostasis? Explain the ideas of Airy and Pratt regarding Homeostasis.

The condition which balances the upper and lower parts of the earth’s crust is called ‘geo-equilibrium’ or isostatic condition. The term isostasy was first used by American geologist Dutton in 1889. Because of homeostasis, mountains, plateaus, plains, and seas are situated side by side. Exogenous forces always keep accumulating the soil in the plains and seas by cutting it from the mountains. That’s why the weight on the plains and the bottom of the sea is more and the weight on the mountains is less. Due to lack or excess of load, the pressure of the earth’s crust on the earth is not equal. 


Homeostasis helps reduce pressure deficit or excess. The height of mountains on the earth’s crust decreases by denudation. Through equanimity, the mountains rise again. In this way, the balance of both mountains, plains, and oceans remains the same. The structure of the earth and the changes taking place on it can be explained keeping in view the homeostasis theory. 

This principle means that wherever there is equilibrium on the earth’s surface, there will be a proportional land area below the surface as per the parts raised on the surface. A continent that is on average 1600 meters above the mean depth of the sea, must be made of a different material than the bottom of the sea and it will have considerable extension down towards the earth because only in this condition the continent and the ocean are in permanent equilibrium. Can stay on the stage. The general meaning of balance is “the state of physical or mechanical stability in the raised and lowered areas of the rotating earth.”

According to J.A. Steers, “Wherever equilibrium is established on the surface of the earth, there are equal amounts of matter under the same surface areas.”

Arthur Holmes, while explaining land balance, has said that “the condition of balance which is found on the earth’s surface between mountain ranges, plateaus, plains or sea bottoms of different heights, is called weight or land balance.”

It has been proved by the study of seismic waves that the density of different parts of the earth is different. This has been confirmed by the research done by the Survey of India. In 1859 AD, two methods were used while finding the latitude in the middle of the Ganga-Indus plain- 

1) the Plumb method, 

(2) the Triangulation method. 

There is a big difference in the result obtained by both methods. The plumb line had to be attracted toward the Himalayan Mountains. Seeing the vastness of the Himalayan site, it was not attracted as much as it should have been. The attraction of the Himalayas on the plumb line was not for 15 seconds but only for 5 seconds. In the year 1855, it was proved that the density of the rocks below the Himalayas is not high but it is less than the average density of the earth (2.7).

 In short words, it can be said that there is an empty or ineffective space within the Himalayan Mountains. It was also proved that the density of the sea floor is higher than the average density of the earth. The important conclusions drawn by the above-mentioned research are- (1) Low-density regions tend to sink downwards. (2) Water is attracted from the part of less density to the part of higher density.

Pratt’s Opinion

According to Ghat, the originator of the homeostatic theory, homeostatic force is active at all times. Due to denudation on the surface, the load becomes lighter, on the other hand, the deposition in the lower parts of the earth’s crust keeps on increasing and the time comes soon when the soft rocks of the earth become mobile and they move from the more dense part of the earth. starts moving towards the region of lower density. As a result, the Earth’s surface starts sinking in the high-density area and rises in the low-density area. In other words, to maintain the balance between different landforms and also to balance the local excess attraction, it is necessary to have a low density of the expanded substances below the surface.

By giving the form of theory, Pratt has tried to explain the situation. They say that the terrestrial pillars whose height is high, their density is relatively high. Thus, the similarity of higher columns is less than the higher density of smaller columns. For this reason, the pressure of the upper and lower parts is the same on the equilibrium line. The lighter parts of the crust can be compared to pieces of zinc and silver, and the heavier parts to heavier objects such as gold and lead. If these pieces of metals of different weights are allowed to float in a vessel filled with mercury in such a way that they are immersed in the mercury to the same depth, then each piece will have to be smaller or bigger to bring the same weight. The bigger piece would have come out with more mercury than the smaller one.

Many scholars have opposed the above opinion of Pratt and have said that the divisions of the earth’s crust

The distribution of metals is not found in separate sections, as in the example of different metals.

Airy’s Opinion

Airy presented his opinion in 1859 AD. According to him, every part of the earth’s crust is equal, the higher the part, in the same proportion its sufficient part is entered into the ground, the less high part, its less part is sunk into the ground. Airy compared the different landforms of the earth to a floating humeral floating in the water. Plavi

As much as part of the iceberg remains above, about eight times its part remains below. According to Archimedes, any floating object displaces a liquid equal to its volume. 19 parts of the ice (ice) remain above the water and the remaining 89 parts are immersed in the water. For every elevated part of the surface, eight times its part lies below the surface of the substratum. 

To prove this idea, Airy compared different parts of the earth’s crust with small pieces of iron metal. If pieces of iron of different dimensions are immersed in mercury, then the larger pieces will be immersed more than the smaller pieces to keep the balance. Airy has said that due to the high standing of the mountains, their roots have to be immersed more deeply in the earth which keeps them in balance.

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