Both the Quran and science agree to the structural makeup of mountains and the role they play in maintaining the stability of the Earth.
A book entitled Earth is a basic reference textbook in many universities around the world. One of its two authors is Professor Emeritus Frank Press. He was the Science Advisor to former US President Jimmy Carter, and for 12 years was the President of the National Academy of Sciences, Washington, DC. His book says that mountains have underlying roots.[1] These roots are deeply embedded in the ground, thus, mountains have a shape like a

Modern earth sciences have proven that mountains have deep roots under the surface of the ground (see figure 3) and that these roots can reach several times their elevations above the surface of the ground.[2] So the most 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.[3]

Mountains also play an important role in stabilizing the crust of the earth.[4] They hinder the shaking of the earth. God has said in the Quran:

“And He has set firm mountains in the earth so that it would not shake with you...” (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.[5]
Could anyone during the time of the Prophet Muhammad have known of the true shape of mountains? Could anyone 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 Quranic verses.
Description: Barriers between various types of water found in nature: a fact mentioned in the Quran expounded by science.

Modern Science has discovered that in the places where two different seas meet, there is a barrier between them. This barrier divides the two seas so that each sea has its own temperature, salinity, and density.[1] For example, Mediterranean sea water is warm, saline, and less dense, compared to Atlantic ocean water. When Mediterranean sea water enters the Atlantic over the Gibraltar sill, it moves several hundred kilometers into the Atlantic at a depth of about 1000 meters with its own warm, saline, and less dense characteristics. The Mediterranean water stabilizes at this depth[2] (see figure 1).

Figure 1: The Mediterranean sea water as it enters the Atlantic over the Gibraltar sill with its own warm, saline, and less dense characteristics, because of the barrier that distinguishes between them. Temperatures are in degrees Celsius (C°). (Marine Geology, Kuenen, p. 43, with a slight enhancement.)

Although there are large waves, strong currents, and tides in these seas, they do not mix or transgress this barrier.

The Holy Quran mentioned that there is a barrier between two seas that meet and that they do not transgress. God has said:

“He has set free the two seas meeting together. There is a barrier between them. They do not transgress.” (Quran 55:19-20)

But when the Quran speaks about the divider between fresh and salt water, it mentions the existence of “a forbidding partition” with the barrier. God has said in the Quran:

“He is the one who has set free the two kinds of water, one sweet and palatable, and the other salty and bitter. And He has made between them a barrier and a forbidding partition.” (Quran 25:53)

One may ask, why did the Quran mention the partition when speaking about the divider between fresh and salt water, but did not mention it when speaking about the divider between the two seas?

Modern science has discovered that in estuaries, where fresh (sweet) and salt water meet, the situation is somewhat different from what is found in places where two seas meet. It has been discovered that what distinguishes fresh water from salt water in estuaries is a “pycnocline zone with a marked density discontinuity separating the two layers.”[3] This partition (zone of separation) has a different salinity from the fresh water and from the salt water[4] (see figure 2).

Figure 2: Longitudinal section showing salinity (parts per thousand ‰) in an estuary. We can see here the partition (zone of separation) between the fresh and the salt water. (Introductory Oceanography, Thurman, p. 301, with a slight enhancement.)

This information has been discovered only recently, using advanced equipment to measure temperature, salinity, density, oxygen dissolubility, etc. The human eye cannot see the difference between the two seas that meet, rather the two seas appear to us as one homogeneous sea. Likewise, the human eye cannot see the division of water in estuaries into the three kinds: fresh water, salt water, and the partition (zone of separation).