A book entitled "Earth" is considered a basic reference text in many universities around the world. One of the authors of this book is Frank Press. He is currently the President of the Academy of Sciences in the USA. Previously, he was the science advisor to former USA President Jimmy Carter. His book says that mountains have underlying roots
[p. 435]. These roots are deeply embedded in the ground. So mountains have a shape like a peg as is seen in an example on page 220 in the same book. Another illustration shows how the mountains are peg-like in shape, due to their deep roots
This is how the Quran described mountains. God said in the Quran:
Have We not made the earth as a bed, and the mountains as pegs?
[Noble Quran 78:6-7]
Modern earth sciences have proven that mountains have deep roots under the surface of the ground and that these roots can reach several times their elevations above the surface of the ground. So the suitable word to describe mountains on the basis of this information is the word 'peg', since most of a properly set peg is hidden under the surface of the ground. The history of science tells us that the theory of mountains having deep roots was introduced only in the latter half of the nineteenth century.
[Geological Concept of Mountains p.5]
Mountains also play an important role in stabilizing the crust of the earth.
[Geological Concept of Mountains pp. 44-45]. They hinder the shaking of the earth. God said in the Quran:
And He has set firm mountains in the earth so that it would not shake with you...
[Noble Quran 16:15]
Likewise the modern theory of plate tectonics holds that mountains work as stabilizers for the earth. This knowledge about the role of mountains as stabilizers for the earth has just begun to be understood in the framework of plate tectonics since the late 1960's
[Geological Concept of Mountains p. 5].
Could anyone during the time of the prophet Muhammad (peace be upon him) have known of the true shape of mountains? Could any one imagine that the solid massive mountain which he sees before him, actually extends deep into the earth and has a root, as scientists assert? A large number of books of geology when discussing mountains, only describe that part which is above the surface of the earth. This is because these books were not written by specialists in geology. However, modern geology has confirmed the truth of the Quran's verses.
What about the water covering the earth? Is there another clue hiding beneath the seas?
The Quran on Deep Seas and Internal Waves