There are large waves, strong currents, and tides in the Mediterranean Sea and the Atlantic Ocean. Mediterranean Sea water enters the Atlantic by Gibraltar. But their temperature, salinity, and densities do not change, because of the barrier that separates them.
After 1962 AD there was known the role of sea barriers in modifying the properties of the water masses that pass from one sea to another, to prevent one sea from overwhelming the other. So salty seas retain their own properties and boundaries by virtue of these barriers.
A field study comparing the waters of Oman Gulf and those of the Arabian Gulf has shown the difference between them regarding their chemical properties, the prevalent vegetation and the barrier separating them.
About a hundred years of research and study has been required to discover the fact of the existence of barriers between sea water masses and their role in making each sea retain its own properties. Hundred of researchers took part and numerous precise scientific instruments and equipment were used to achieve that.
Fourteen centuries ago the Holy Qur’an revealed this fact.
Allah (SWT) says: (He has let free (MARAJA) the two sees meeting together. Between them is a barrier that they do not transgress. Then which of the Blessings of your Lord will you both (Jinn and men) deny? Out of them both come out pearls and carol.” (LV: 19-22) Allah (SWT) also says: “And He made a barrier between the two seas.) (XXVII: 61)
Linguistic meanings and the commentators’ sayings:
Maraja (let free):
Ibn Faris said: “’maraja’: The consonants m, r and j form a root indicating a movement of going and coming and turbulence.”
Al-Bahrayn (the two seas):
Al-Asfahani said: “Some say that the word “bahr” (sea) is usually used to mean salt water rather than fresh water.”
Ibn Manzursaid: “’Bahr’ is more frequently used to describe salt water than fresh water.”
If the word “bahr” is used without qualification it means salt water; otherwise, it means the thing qualified.” The Holy Qur’an uses “nahr” (river) to indicate abundant running fresh water, while it uses “bahr” (sea) to indicate salt water. Allah (SWT) says: (And He has made the ships to be of service to you that they may sail through the sea by His Command; and He has made rivers (also) to be of service to you.)(XIV: 32)
In the hadith, “bahr” (sea) is also used to mean salt water. Allah’s Messenger (Peace be upon him) was asked by a man who said: “O Allah’s Messenger! We travel by sea and carry with us a little fresh water. If we should use it for wudu (ablution) we would get thirsty. May we use seawater for wudu? Allah’ Messenger (Peace be upon him) said: “Its water is pure and its dead (animals) are lawful (to eat).”
Al-Barzakh: It is the barrier. Most commentatorssuggest that it is invisible.
Al-baghi: Ibn Manzur said: “’Al-Baghi’ means transgression, exceeding the limits.”
Al-Jawhari and Al-Asfahani said the same.
Al-Marjan: Ibn Al-Jawzi said: “Al-Qadi Abu Ya’li says that Al-Marjan is a kind of bar-like pearls. Al-Zajjajsaid: “Al-Marjan is white, very white.” Ibn Mas’ud said: “Al-Marjan is red beads.” Abu Hayyan said that to some people Al-Marjan is red stone. Al-Qurtubi said: “It is said that Al-Marjan is the big pearls. The same is also said by ‘Ali and Ibn ‘Abbas (May Allah bestow His Mercy on them both). The small pieces of Marjan are the small pearls. It is also reported on their authority the opposite: the big pieces are called pearls and the smaller are called Marjan. Al-Dahhak and Qatadah said the same.”
Al-Alusi said: “If we take into consideration the connotation of brilliance and glitter which the Arabic word “pearls” carries, and the connotation of movement and mixing that the word “Marjan” carries, we can say that “pearls” is used for big pieces and “Marjan” for small ones.”
Anyhow, Marjan is a kind of ornament that is found in various colors: white and red. It may be in big or small pieces. It is bar-like stone. In the Verse it is something other than pearls, for the conjunction “and” implies talking bout two different things. Marjan (carol), however, is found in salt seas only.
The Verse shows us the minute secrets which oceanography has revealed only recently. They describe the meeting between salt seas. Following is the evidence to that:
First: The Verse uses the word “bahrayn” (two seas) without any qualification. This means that salt seas are intended here.
Second: The Verses in Surat Al-Rahman show that the two seas yield pearls and “Marjan”(carol). It has become evident that Marjan is found in salt seas only. This indicates that the Verse is referring to two salt seas. Allah (SWT) says: “Out of them both come out pearls and carol,” i.e. out of each of them.
Who knew in the past that salt seas differ in many respects in spite of their apparent similarity to the observer? (They all taste salt, look blue, have waves, contain fish, etc.) How can they differ although they meet each other? We know that when two amounts of water are mixed in a container they get homogenous. How can seas remain differentiated even in the presence of the factors of mixing, such as the ebb and flow of the sea, currents and storms?
The Verse mentions the meeting of two salt seas that differ from one another. If the two seas were similar to one another, they would be one sea. However, differentiating between them in the Qur’anic utterance implies the difference between them although they are both salt.
(He has let free (Maraja) the two seas meeting together) means that the two seas are mixed; they are in the state of backward and forward movements, of mixing and turbulence at the site of the meeting, as is understood from the literal meaning of “Maraja”. This is the fact that science has discovered, that is to say, the barrier is described as being zigzag or wavy and shifting in position during the various seasons because of the tide and winds.
This Verse by itself implies the presence of so much mixing and merging between these seas as would deprive them of their distinctive properties. But Allah (SWT), the All-Knower, shows in the following Verse that “between them is a barrier which they do not transgress”, i.e. In spite of this state of merging and turbulence that characterizes the seas there is a barrier between them preventing them from transgressing or exceeding their limits.
This is what man has discovered as a result of the advances achieved in his sciences and instruments. It has been found that a third water mass separates the two seas and it has such properties as are different from those of each of the two seas separated by it.
Yet, in spite of the presence of the barrier, the waters of the two adjacent seas mix very slowly without one sea encroaching upon the other through carrying over its own properties to it, for the barrier zone is a region for changing the water crossing from one sea to the other so that it gradually acquires the properties of the sea that is going to enter and loses the properties of the sea it has come form. Thus neither of the two seas transgresses by carrying its own properties to the other, although they mix during the process of meeting. How truthful is Allah’s Saying: (He has let free (maraja) the two seas meeting together. Between them is a barrier which they do not transgress.)
Most commentators suggest that the barrier that separates the two seas referred to here is an invisible barrier created by Allah. Some commentators find it difficult to reconcile the idea of the seas being merging and the presence of a barrier at the same time, for the presence of a barrier entails the prevention of merging. So the mention of merging (maraja) entails the absence of a barrier. This apparent contradiction has been resolved by discovering the secrets of the seas.
The Miraculous Aspects of the Previous Verses:
We can conclude the following from the discussion above:
The Holy Qur’an, which was revealed more than 14 centuries ago, includes very precise pieces of information and knowledge about marine phenomena that have been discovered only recently by means of very sophisticated equipment. An instance in this respect is the existence of water barriers between seas. Allah (SWT) says: (He has let free (maraja) the two seas meeting together. Between them is a barrier which they do not transgress.)
The historical development of Oceanography shows that no precise information had been available on seas before Challenger Expedition (in 1873 AD), let alone at the time when the Holy Qur’an was being revealed 14 centuries ago to an illiterate Prophet that lived in a desert environment and never traveled by sea.
Oceanography has witnessed no advances except in the last two centuries, particularly in the latter half of the twentieth century. Prior to that a sea was considered as something fearful and mysterious. Myths and superstitions were fabricated about it. Sea voyagers were only interested in their own safety and how to find the correct routes during their long journeys. Man discovered that salt seas are different only in the thirties of the twentieth century, after thousands of marine stations had been established by researchers to analyze samples of sea water to measure the differences between the degrees of temperature, salinity, density and oxygen dissolubility in the sea water recorded at all those stations, and then realize that salt seas are different.
Man did not know anything about the barrier that separates between salt seas till the establishment of the aforesaid stations, and after spending a long time tracing these wavy moving barriers that change their geographical locations with the change of seasons.
Man did not know that the water masses of the two seas are separated by a water barrier and are mixed at the same time till he started studying with his ships and equipment the water movement in the meeting region of the seas and analyzing the water masses in those regions.
Man did not apply this rule to all seas that meet together except after vast scientific surveying, investigation and verification of this phenomenon, which occurs between each pair of adjacent seas in the world.
Now then, did Allah’s Messenger (Peace be upon him) own stations and equipment for analyzing water and the ability to trace the movement of various water masses? Did he carry out a comprehensive surveying process, although he never sailed the sea and lived at a time when superstitions were prevalent, particularly in the field of seas? Were, at the time of Allah’s Messenger (Peace be upon him) such researches, instruments and studies as are available for the oceanographers of today who have discovered all these secrets by means of research and study?
This knowledge, which the Qur’an came with, included a precise description of the subtlest secrets at a time when humanity could never have known them, which indicates that its source is Divine, as Allah (SWT) says: (Say: “the (Qur’an) was sent down by Him Who knows the secret (that is) in the heavens and the earth: Verily He is Oft-Forgiving, Most Merciful.) (XXV: 6)
It also indicates that the one to whom the Book was sent down was a Messenger inspired. Allah (SWT) but says the Truth in the Verse: (Soon will We show Our Signs in the Universe and in their own selves, until it becomes manifest to them that this the Truth. Is it not sufficient that your Lord does witness all things?)