Buffon's Natural History, Volume 02 (of 10) / Containing a Theory of the Earth, a General History of Man, of the Brute Creation, and of Vegetables, Mineral, &c. &c

by comte de Georges Louis Leclerc Buffon

The coasts of the sea may be distinguished into three kinds, 1st, the elevated coasts, which are rocks and hard stones, generally divided perpendicularly, and which rise sometimes to the height of 7 or 800 feet. 2d, The low coasts, some of which are almost level with the surface of the water, and others rising with a moderate elevation, often bounded by rocks at the water's edge, forming shelves and breakers, which render the approach to shore very difficult and dangerous. 3dly, Downs, which are coasts formed by sand which the sea accumulates, or brought or deposited by rivers; these downs form hills more or less elevated, according to the accumulated sand.

The coasts of Italy are bordered by several sorts of marble and stone; these rocks appear at a distance as so many pillars of marble perpendicularly divided. The coasts of France from Brest to Bourdeaux are almost surrounded with rocks just at the water's edge, which occasion dangerous breakers. The coasts of England, Spain, and many others, are also bordered with rocks and hard stone; excepting some parts which are made use of for bays, ports, and havens.

The depth of water along the coasts is in proportion to their elevation. The inequalities at the bottom of the sea near the coasts, correspond also with the inequalities of the surface of the ground along the shore. A celebrated navigator has made the following observations on this subject.

"I have constantly remarked, that where the coasts are defended by steep rocks, the sea is there very deep, and seldom affords a probability of anchoring; and, on the contrary, where the ground inclines from the coast to the sea, however elevated it may be further inland, the bottom is good there, and consequently admits of anchorage.

"According to the declivity of land, as it approaches the water's edge, so we generally find our anchor ground, and either approach or keep at a distance from shore agreeable to the steepness of the land; for I never saw or heard of a coast where the land is of a continual height, without some vallies lying intermixed with the high-lands; they are the subsiding of low lands, and afford good anchoring, the earth being lodged deep under water; for this reason it is we find good harbours upon coasts which abound with steep cliffs, because the land has subsided between them. But Where the declensions from the hills is not within land but towards the main sea, as at Chili and Peru, and the coasts are nearly perpendicular, as in the countries running from the Andes, it is very deep, and has scarcely any creeks or harbours. The coasts of Gallicia, Portugal, Newfoundland, the islands of Juan Fernando and St. Helena, &c. are somewhat similar to those of Peru, yet good harbours are not so scarce, as there is always good anchorage where there are short ridges of land. In general the land under water seems to be exactly proportioned to the rising of the contiguous part above, and therefore, where the lands upon the shores are steep, there is but little security for ships, they being very easily driven from their moorings; yet although steep cliffs denote this disadvantage, they assure us of this benefit also, that we can sail close to them with safety, besides being able to see them at a considerable distance; whereas low lands are frequently not discovered until we are near, and always experience the hazard of running aground. This fact of good anchorage where the lands on the coast are low, might be illustrated by many instances in the bays of Campeachy, Honduras, Panama; the coasts of Portobella, Carthagena, Guinea, Callifornia, China, Coromandel, &c. but going into particulars would be almost endless, as I very seldom found it otherwise than that deep waters and high shores went together, as well as low lands and shallow seas."

The fact therefore of there being considerable mountains, and other inequalities, at the bottom of the sea is fully confirmed by the observations of navigators. Divers also assure us, there are smaller inequalities formed by rocks, and that it is much the coldest in the vallies of the sea. In general the depths in great seas, as we have already observed, increase proportionably to their distance from shore. By Mr. Buache's chart of that part of the ocean between the coasts of Africa and America, and by the divisions he has given of the sea from Cape Tagrin to Rio-Grande, there appears to be similar inequalities in the ocean to those on land. That the Albrolhos, where there are some rocks at the surface of the water, are only the tops of very large and lofty mountains, of which Dolphin island is one of the highest peaks. That the islands of Cape de Verd are also the tops of mountains that there are a great number of shoals in the sea, which round the Albrolhos descends even to unknown depths.

With respect to the quality of the different soils which form the bottom of the sea, as we must rely on divers and the plumb, we can say nothing exact or precise concerning it; we only know that there are parts covered with mud to a considerable thickness, on which anchors have no hold; in these parts probably the mud of rivers are deposited. In other parts are sands similar to those on land. In others are shells, heaped up together, madrepores, corals, and other productions of insects, which begin to unite and appear like stones; in others are fragments of stones, gravel, and often entire stones and marble. For example, in the Maldivian islands the buildings are made of a hard stone weighed up from several fathoms under water. At Marseilles very good marble is obtained from the bottom of the sea, which, so far from wasting and spoiling stone and marble, in our discourse on minerals, we shall prove they are formed and preserved therein; whereas the sun, earth, air, and rain water, corrupts and destroys them.

The bottom of the sea must be composed of the same matters as our habitable land, because the very same substances are contained in the one as the other; places are found at the bottom of the sea, covered with shells, madrepores, and other productions of sea matters, as we meet with on earth an infinity of quarries and banks of chalk and other matters replete with the same sort of shells, madrepores, &c. so that in all respects the dry parts of the globe resemble those covered by the water, both in composition of matters, and inequalities of the superfices.

It is to these inequalities at the bottom of the sea, we must attribute the origin of currents, for if the bottom was equal and level, there would be no other current than the general motion from east to west, and a few others which might be caused by the action of the winds; but a certain proof that most currents are produced by the flux and reflux, and directed by the inequalities at the bottom of the sea, is, that they regularly follow the tides, and change their direction at each ebb and flow. See Pietra della Valle on the subject of the currents of the gulph of Cambay, and the accounts of all navigators, who unanimously assert that in those parts where the flux and reflux of the sea is the most violent, the currents are also most rapid.