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.