Buffon's Natural History, Volume 01 (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

I have chosen this example, as the most disadvantageous to my theory, because it at first appears very difficult to conceive that the dust of the air, rain and dew, could produce strata of free earth thirteen feet thick; but it ought to be observed, that it is very rare to find, especially in high lands, so considerable a thickness of cultivateable earth; it is generally about three or four feet, and often not more than one. In plains surrounded with hills, this thickness of good earth is the greatest, because the rain loosens the earth of the hills, and carries it into the vallies; but without supposing any thing of that kind, I find that the last strata formed by the waters are thick beds of marl. It is natural to imagine that the upper stratum had, at the beginning, a still greater thickness, besides the thirteen feet of marl, when the sea quitted the land and left it naked. This marl, exposed to the air, melted with the rain; the action of the air and heat of the sun produced flaws, and reduced it into powder on the surface; the sea would not quit this land precipitately, but sometimes cover it, either by the alternative motion of the tides, or by the extraordinary elevation of the waters in foul weather, when it mixed with this bed of marl,

mud, clay, and other matters. When the land was raised above the waters, plants would begin to grow, and it was then that the dust in the rain or dew by degrees added to its substance and gave it a reddish colour; this thickness and fertility was soon augmented by culture; by digging and dividing its surface, and thus giving to the dust, in the dew or rain, the facility of more deeply penetrating it, which at last produced that bed of free earth thirteen feet thick.

I shall not here examine whether the reddish colour of vegetable earth proceeds from the iron which is contained in the earths that are deposited by the rains and dews, but being of importance, shall take notice of it when we come to treat of minerals; it is sufficient to have explained our conception of the formation of the superficial strata of the earth, and by other examples we shall prove, that the formation of the interior strata, can only be the work of the waters.

The surface of the globe, says Woodward, this external stratum on which men and animals walk, which serves as a magazine for the formation of vegetables and animals, is, for the greatest part, composed of vegetable or animal

matter, and is in continual motion and variation. All animals and vegetables which have existed from the creation of the world, have successively extracted from this stratum the matter which composes it, and have, after their deaths, restored to it this borrowed matter: it remains there always ready to be retaken, and to serve for the formation of other bodies of the same species successively, for the matter which composes one body is proper and natural to form another body of the same kind. In uninhabited countries, where the woods are never cut, where animals do not brouze on the plants, this stratum of vegetable earth increases considerably. In all woods, even in those which are sometimes cut, there is a bed of mould, of six or eight inches thick, formed entirely by the leaves, small branches, and barks which have perished. I have often observed on the ancient Roman way, which crosses Burgundy in a long extent of soil, that there is formed a bed of black earth more than a foot thick upon the stones, which nourishes very high trees; and this stratum could be composed only of a black mould formed by the leaves, bark, and perished wood. As vegetables inhale for their nutriment much more

from the air and water than the earth, it happens that when they perish, they return to the earth more than they have taken from it. Besides, forests collect the rain water, and by stopping the vapours increase their moisture; so in a wood which is preserved a long time, the stratum of earth which serves for vegetation increases considerably. But animals restoring less to the earth than they take from it, and men making enormous consumption of wood and plants for fire, and other uses, it follows that the vegetable soil of inhabited countries must diminish, and become, in time, like the soil of Arabia Petrea, and other eastern provinces, which, in fact, are the most ancient inhabited countries, where only sand and salt are now to be met with; for the fixed salts of plants and animals remain, whereas all the other parts volatilise, and are transported by the air.

Let us now examine the position and formation of the interior strata: the earth, says Woodward, appears in places that have been dug, composed of strata placed one on the other, as so many sediments which necessarily fell to the bottom of the water; the deepest strata are generally the thickest, and those above the thinnest, and so gradually lessening to

the surface. We find sea shells, teeth, and bones of fish in these different beds, and not only in those that are soft, as chalk and clay, but even in those of hard stone, marble, &c. These marine productions are incorporated with the stone, and when separated from them, leave the impressions of the shells with the greatest exactness. "I have been most clearly and positively assured," says this author, "that in France, Flanders, Holland, Spain, Italy, Germany, Denmark, Norway, and Sweden, stone, and other terrestrial substances are disposed in strata, precisely the same as they are in England; that these strata are divided by parallel fissures; that there are inclosed within stones and other terrestrial and compact substances, a great quantity of shells and other productions of the sea, disposed in the same manner as in this island. I am also informed that these strata are found the same in Barbary, Egypt, Guinea, and in other parts of Africa; in Arabia, Syria, Persia, Malabar, China, and the rest of the provinces of Asia; in Jamaica, Barbadoes, Virginia, New-England, Brazil, and other parts of America[198:A]."

This author does not say how he learnt, or by whom he was told, that the strata of Peru contained shells; yet as in general his observations are exact, I do not doubt but he was well informed; and am persuaded that shells may be found in the earth of Peru, as well as elsewhere. This remark is made from a doubt having been formed some time since on the subject, and which I shall hereafter consider.

In a trench made at Amsterdam, to the depth of 230 feet, the strata were found as follows: 7 feet of vegetable earth, 9 of turf, 9 of soft clay, 8 of sand, 4 of earth, 10 of clay, 4 of earth, 10 of sand, then 2 feet of clay, 4 of white sand, 5 of dry earth, 1 of soft earth, 14 of sand, 8 of argil, mixed with earth; 4 of sand, mixed with shells; then clay 102 feet thick, and at last 31 feet of sand, at which depth they ceased digging[199:A].