The cocoa-trees, which are at the bottom of the sea, is a proof that the Maldivians were formerly part of the continent: cocoa-nuts are often detached from them and thrown on the shore by a storm.
It is imagined that the island of Ceylon was formerly united to the continent, and that the currents, which are extremely rapid in many parts of India, have divided that as well as Rammanakoil, and many other islands.[AY] However, it is certain that the island of Ceylon has lost 30 or 40 leagues of ground towards the north-west side, which the sea has gained.
[AY] See the Dutch Travels to the East-Indies, vol. II. p. 486.
It appears that the sea has recently forsaken a great part of the projecting lands and islands of America. We have just observed, that the ground of Jucatan is filled with shells. It is the same with the low lands of Martinico and the other Antille islands. The inhabitants have termed the earth below the surface lime, because they make their lime with these shells, considerable banks of which are found immediately under the vegetable earth. In the new voyages to the islands of America it is said, "lime, which is found in the land of Guadaloupe, when the earth is turned up, is of the same kind as that drawn out of the sea, the reason of which is difficult to be assigned. Might it not be possible, that all the extent of ground, which composes this island, was, in former times, only a high ground filled with lime-plants, which having grown and filled the void spaces that were occupied by the water, have raised up the ground, obliged the water to retire, and leave all the superficies dry? This conjecture, as extraordinary as at first it may appear, has, nevertheless, nothing impossible in it; and if the people who reside there were to dig in different parts of the earth they would discover what the real soil is, and by that means destroy or strengthen my conjecture."
There are some lands which are sometimes covered with water and sometimes uncovered, as many islands in Norway, Scotland, Maldivias, the gulph of Cambaya, &c. The Baltic has, by little and little, gained a great part of Pomerania, and covered and destroyed the famous port of Vineta. So likewise the sea of Norway has projected into the continent, and formed many small islands. The German sea has projected into Holland near Cat, insomuch that the ruins of an ancient citadel of the Romans, which was formerly on the coast, are now very far in the sea. The marshy grounds in the Isle of Ely, in England, and those in Provence, in France, are, on the contrary, as we have observed, land which the sea has abandoned. Downs have been formed by the sea-winds, which have thrown and accumulated earth, sand, shells, &c. on the shore. For example, on the western coast of France, Spain, and Africa, durable and violent westerly winds reign, which impel the waters towards the shore with great impetuosity, and on which coasts downs are very frequent. In the like manner the easterly winds, when they remain any long time, so strongly drive the waters from the coasts of Syria and Phœnicia that the chain of rocks, which are covered with water during the westerly winds, are left quite dry. Thus downs are never composed of stone, or marble, like mountains formed in the bottom of the sea, because they have not been long enough under the water. In our discourse on minerals we shall shew that the sea possesses the power of petrifaction, and that the stones formed in the earth are quite different from those formed in the sea.
When I had just finished my Theory of the Earth, which I composed in 1744, I received from Mons. Barrere, his dissertation on the origin of figured stones, and I was pleased to find myself of the same opinion with this able naturalist, on the subject of the formation of downs, and the time the water remained on the earth which we inhabit; he recounts many alterations which have happened to the sea coasts: "Aiguis-mortes, which is now more than a league and a half from the sea, was a port in the time of St. Louis: Psalmodi was an island in 815, and at present it is inland two leagues from the sea. It is the same with respect to Maguelone. The greatest part of the vineyards of Agde, was forty years ago covered by the sea: and in Spain the sea has considerably retreated within a short space of time from Blancs, Badalona, the mouth of the river Vobregat, Cape Tortosa, along the coasts of Valentia, &c.
"The sea may form hills and mountains in many different manners; first, by the transportations of earth, sand, and shells, from one place to another; secondly, by depositing sediments, consisting of small particles detached from the coasts and bottom, and which it might have transported from a considerable distance; and lastly, by sand, mud, and other articles, which the sea winds often drive against coasts, downs and hills may be produced, which the water forsaking, by degrees, become parts of the continent." The downs of Flanders and Holland are of this kind, being only hills composed of sand and shells, which the sea winds have driven towards the land. Mons. Barrere quotes another example which merits a place in this work. "The sea, by its motion, detaches from its bottom an infinity of plants, shells, slime, and sand, which the waves and winds continually drive towards the shore. Now, all these different operations must continually form new strata, elevate the beds of earth, gradually raising downs and hills, retrenching the bounds of the ocean, and by that means extending the lands on the continents."
"It is visible that new strata have been successively formed by the same reiterated motion of the waters from the deposition of sediments and other constant causes from time immemorial; of which I find strong proofs in the different beds of fossils, shells, and other marine productions found in Roussillon near the village of Naffiac, about seven or eight leagues from the sea; these beds of shells which are inclined from the west to the east, and in different angles, are separated from each other by banks of sand and earth, are sometimes from one and a half to two or three feet in thickness. They appear as if sprinkled with salt in dry weather, and form together hillocks from twenty-five to thirty fathoms in height: now a long chain of hills of such an height can only be formed gradually, and at different successions of time. Such might be the effect of an universal deluge, which must have disturbed all nature; but which could not have given a regular form to these different beds of fossil shells, but would have jumbled them together without any order or regularity."
On this subject I am perfectly of the same opinion as M. Barrere, excepting as to the formation of mountains, which I cannot agree ought to be entirely attributed to the causes which occasion the ocean to gain upon the land on some parts, and lose it upon others. As I am, on the contrary, of opinion, I could produce many convincing arguments to prove that most of the eminencies seen on the surface of the earth have been actually formed in the sea itself. First, because they have a correspondence of saillant and returning angles, which necessarily implies the cause we have assigned, that is, the motion of the currents. Secondly, because downs and hills, which are formed by the materials that the sea brings on its shores, are not composed of marble and hard stone, like common hills; the shells also in the former are generally only fossils, whereas in the latter, the petrifaction is compleat; besides the beds of earth are not so horizontal in downs as in the hills composed of marble and hard stone, but are more or less inclined, as in the hills of Naffiac, whereas in the hills and mountains, formed under the water by the sediment of the sea, the strata are always parallel, and very often horizontal, and the shells and other marble are entirely petrified. I have no doubt of proving that marble and other calcinable matters, which are almost all composed of madrepores, astroites, and shells, have acquired their hardness and perfection at the bottom of the sea; on the contrary, gravel, soft stones, incrustations, stalactites, &c. which are also calcinable and found in the earth, and formed since our continent has been discovered, cannot acquire this degree of hardness and petrifaction which marble or hard stones have.
In the history of the French Academy for 1708, may be seen the observations of Saulmon, on the subject of the galets found in many places. These galets are round and flat flints very smooth, and which are cast on the shores by the sea. At Bayeux, and at Prutel, which are a league from the sea, we find them in digging wells or pits. The mountains of Bonneuil, Broie, and Quesny, which are eighteen leagues from the sea, are all covered with galets; they are also found in the valley of Clermont in Beauvois. M. Saulmon likewise relates, that a hole, 16 feet deep, was bored horizontally into the beach of Tresport, which is soft earth, and that it entirely disappeared in 30 years: so that if the sea always encroaches alike, it would gain half a league in 12,000 years.