We placed firmly embedded mountains on the earth, so it would not move under them… (Qur'an, 21:31)
Mountains emerge as a result of the movements and collisions of massive plates forming the Earth's crust. When two plates collide, the stronger one slides under the other, the one on the top bends and forms heights and mountains. The layer beneath proceeds under the ground and makes a deep extension downward. Consequently, as stated earlier, mountains have a portion stretching downwards, as large as their visible parts on the Earth.
In a scientific text, the structure of mountains is described as follows:
Where continents are thicker, as in mountain ranges, the crust sinks deeper into the mantle.25
Professor Siaveda, a world-renowned underwater geologist, made the following comment in reference to the way that mountains have root-like stalks attaching them to the surface:
The fundamental difference between continental mountains and the oceanic mountains lies in its material... But the common denominator on both mountains are that they have roots to support the mountains. In the case of continental mountains, light-low density material from the mountain is extended down into the earth as a root. In the case of oceanic mountains, there is also light material supporting the mountain as a root... Therefore, the function of the roots are to support the mountains according to the law of Archimedes.26
Furthermore, a book titled Earth, by Dr. Frank Press, former president of the U.S. National Academy of Sciences, which is still used as a text book in a great many universities, states that mountains are like stakes, and are buried deep under the surface of the Earth.27
In other verses, this role of the mountains is pointed out by a comparison with "pegs":
Have We not made the earth as a bed and the mountains its pegs? (Qur'an, 78:6-7)
In another verse it is revealed that Allah "made the mountains firm." (Qur'an, 79:32) The word "arsaha" in this verse means "was made rooted, was fixed, was nailed to the earth." Similarly, mountains extend to the surface layer joining lines on and below the surface, and nail these together. By fixing the Earth's crust they prevent any sliding over the magma layer or amongst the layers themselves. In short, mountains can be compared to nails holding strips of wood together. The fixing effect of mountains is known as isostasy in scientific literature. Isostasy is the state of equilibrium between the upward force created by the mantle layer and the downward force created by the Earth's crust. As mountains lose mass due to erosion, soil loss or melting of glaciers, they can gain mass from the formation of glaciers, volcanic explosions or soil formation. Therefore, as mountains grow lighter they are pressed upwards by the raising force implemented by the liquids. Alternatively, as they grow heavier they are pressed into the mantle by the force of gravity. Equilibrium between these two forces is established by isostasy. This balancing property of mountains is described in these terms in a scientific source:
G.B Airy in 1855 suggested that the crust of the earth could be likened to rafts of timber floating on water. Thick pieces of timber float higher above the water surface than thin pieces and similarly thick sections of the earth's crust will float on a liquid or plastic substratum of greater density. Airy was suggesting that mountains have a deep root of lower density rock which the plains lack. Four years after Airy published his work, J.H Pratt offered an alternative hypothesis... By this hypothesis rock columns below mountains must have a lower density, because of their greater length, than shorter rock columns beneath plains. Both Airy and Pratt's hypothesis imply that surface irregularities are balanced by differences in density of rocks below the major features (mountains and plains) of the crust. This state of BALANCE is described as the concept of ISOSTASY.28
Today, we know that the rocky external layer of the Earth's surface is riven by deep faults and split into plates swimming above the molten lava. Since the Earth revolves very quickly around its own axis, were it not for the fixing effect of the mountains, these plaques would shift. In such an event, soil would not collect on the Earth's surface, water would not accumulate in the soil, no plants could grow, and no roads or houses could be built. In short, life on Earth would be impossible. Through the mercy of Allah, however, mountains act like nails, and to a large extent, prevent movement in the Earth's surface.
We subjected the mountains to glorify [Allah] with him in the
He cast firmly embedded mountains on the earth so it would not move under you, and rivers and pathways so that hopefully
This vital role of mountains, which has been discovered by modern geological and seismic research, was revealed in the Qur'an centuries ago as an example of the supreme wisdom in Allah's creation.
… [He] cast firmly embedded mountains on the earth so that it would not move under you… (Qur'an, 31:10)
24. www.wamy.co.uk/announcements3.html, from an address by Prof. Zighloul Raghib El-Naggar.
25. Carolyn Sheets, Robert Gardner, and Samuel F. Howe, General Science (Newton, MA: Allyn and Bacon Inc.: 1985), 305.
27. Frank Press, and Raymond Siever, Earth, 3rd ed. (San Francisco: W. H. Freeman & Company: 1982).
28. M. J. Selby, Earth's Changing Surface (Oxford: Clarendon Press: 1985), 32.