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Robles, is well known to have been in the year 1570. An hundred years afterwards, the alluvial depositions had added in some places three quarters of a league of new land on the outside of these dikes : and the city of Groningen, partly built upon the ancient soil, which has no connection with the present sea (being a calcareous formation, in which the same species of shells are found as in the coarse limestone formations near Paris), is only six leagues from the sea.
The same phenomenon is as distinctly abservable all along the coasts of East-Friesland and the countries of Bremen and Holstein, as the period, at which the new grounds were inclosed by dikes for the first time, is perfectly well known; and the extent, that has been gained since, can be easily measured. These new alluvial lands, left by the sea and the rivers, are of astonishing fertility: and they are so much the more valuable, as the ancient soil of these countries, being mostly covered by barren heaths and peat-mosses, is almost incapable of cultivation: so that the alluvial lands alone produce subsistence for the many populous cities, that have been built along these coasts since the middle age, and which probably might not have reached their present flourishing condition without the aid of these rich grounds which have been (as it were) created by the rivers and to which they are continually making additions.
The downs or sand-hills, which are thrown ир. the sea upon low flat coasts when the bed of the sea happens to be composed of sand, have been already mentioned. Wherever human industry has not succeeded to fix these downs, they advance as securely and
irresistibly upon the land, as the alluvial formations from the rivers encroach upon the sea. In their progress inland, they push before them great pools of water, formed by the rain which falls on the neighbouring grounds and which has no means of running off in consequence of the obstructions interposed by the downs. In several places, they proceed with a frightful rapidity, overwhelming forests, houses, and cultivated fields, in their irresistible progress.
Those upon the coast of the Bay of Biscay have overwhelmed a great number of villages, which are mentioned in the records of the middle age: and, even at present, in the single department of Landes, they threaten no fewer than ten with almost inevitable destruction. One of these, named Mimigan, has been in danger for the last fifteen years from a sand-hill of more than sixty feet in perpendicular height, which obviously continues to advance.
In the year 1802, the pools overwhelmed five farmhouses belonging to the village of St. Julian. They have long covered up an ancient Roman road, leading from Bourdeaux to Bayonne, which could still be seen about thirty years ago, where the waters were lower than they are now. The river Adour, which is known to have formerly passed Old Boucat to join the sea at Cape Breton, is now turned to the distance of more than 2400 yards.
Mr. Bremontier, who made several extensive works to stop the progress of these downs, estimated it at sixty feet yearly and in some places at seventy two feet. According to this calculation, it would require
two thousand years to enable them to arrive at Bourdeaux : and, on the same data, they have taken somewhat more than four thousand years to reach their present situations.
The turbaries, or peat-mosses, which have been formed so generally in the northern parts of Europe by the accumulation of the remains of sphagnum and other aquatic mosses, afford another mean of estimating the time which has elapsed since the last retreat of the sea from our present continents. These mosses increase in height in proportions which are determinate in regard to each. They surround and cover up the small knolls, upon which they are formed; and several of these knolls have been covered over within the memory of man. In other places, the mosses gradually descend along the valleys, extending downward like the glaciers : but these latter melt away every year at their lower edges, while the mosses are not stopped by any thing whatever in their regular increase. By sounding their depth down to the solid ground, we may form some estimate of their antiquity: and it may be asserted respecting these mosses, as well as respecting the downs, that they do not derive their origin from an indefinitely ancient epoch.
The, same observations may be made in regard to the slips or fallings, which sometimes take place at the bottom of all steep slopes in mountainous regions, and which are still very far from having covered these over.
But, as no precise measures of their progress have hitherto been applied, we shall not insist upon them at any greater length.
From all that has been said, it may be seen, that nature every where distinctly informs us, that the commencement of the present order of things cannot be dated at a very remote period *.
3. With the language of nature and with the general traditions of all nations, the evidence, afforded by what I have called a moral proof, will still be found exactly to accord.
(1.) As all the nations upon the face of the earth, which possess any records or ancient traditions, unanimously declare, that an universal deluge once took place, and that society recommenced from the epoch of that grand revolution : so every account which has come down to us of the progress of civilization, with its concomitant arts and sciences, tends to demonstrate the comparative newness of social order and thence incidentally its commencement from some remarkable epoch of no stupendously remote antiquity.
On the supposition, that the general deluge really took place, and that a single family alone was preserved in the midst of surrounding destruction; it is easy to conceive, what in lapse of time would be the almost certain consequence of such an event. For a season, mankind would remain together, and would industriously preserve and cultivate that knowledge which had been saved from the wreck of a former world. But, ere long, increase of numbers would pro
Essay on the theory of the earth. $ 31, 32. p. 135-149.
duce emigration : and emigration would take place in every direction from the central spot, which was first inhabited. Those who remained together in the originally established society, and those who had the good fortune to plant themselves in rich and fertile countries, retaining the arts and sciences derived from their antediluvian forefathers, would gradually form civilized and well politied communities. But those, who emigrated in small bodies, and who plunged into the depths of trackless forests or fixed themselves in hopelessly barren districts, would soon sink into a state of ignorance and barbarism : for, either the labour of clearing the ground would so occupy them as to preclude much cultivation of mind, or an adoption of the pastoral or hunting life would prove equally unfavourable to the preservation and diffusion of knowledge. Thus, by the very necessity of things, mankind would in a short time be distributed into the two classes of the civilized and the uncivilized.
Yet so great are the advantages of knowledge and union, that, although barbarous nations may often have made successful inroads into the territories of civilized nations, there is a natural tendency in civilization to spread itself and in the end to prevail over and exterminate barbarism. Hence, after a certain number of years, civilization gradually extending and barbarism gradually contracting its limits, the inevitable result must be the univeral diffusion of the light