47. I have already proved, in my firft Letter, that whatever havock the running waters appear to have made in our mountains, all their pretended deftructive power, from the birth of our continents, has only ferved to retard the fettling of the flopes of rubbish at the feet of the steep rocks, and that the greater part of the materials that they have thus fet in motion, at times of great rains and melting of the fnow, has only ferved to raise and level the_bottom_of the vallies which existed before the retreat of the fea. For we find fcarcely any thing but sand at the entrance of those lakes, into which the rivers difcharge themselves as they flow from the mountains, and in which are depofited all the materials which these collected waters, after traverfing the interior parts, have carried down fo far; the whole amount of which is nothing in comparison with what the imagination of fome Geologifts conceived. I have shown alfo, that the known progrefs of these sediments are among the proofs of the flight antiquity of our globe. I now, therefore, fhall quit, though with regret, the abundance of interefting objects for a Geologist, that all parts of a mountainous country afford, that I may proceed to the general effects of running waters on our continents.

48. Wherever the rivers have met with obftacles in their course, they have made an effort to demolish them. I pafs over, (as I have done with respect to the mountains, and the fea coafts,) the solid rocks, on which no external caufe has any fenfible effect, in order to come immediately to thofe places where we may vifibly trace, the whole of paft effects, their progress in known time, and their prefent advance; which fuppofes, that with regard to the rivers, they have been able to make a fenfible impreffion upon the obftacles they have encoun tered. Now, here are two general operations, which began at the time that such obstacles occurred to bend their course. 1. The grounds thus ftruck by the waters were excavated, and cliffs were formed, which continued for a greater or less time, and in many places, ftill continue to crumble down into the current. 2. The materials, thus detached and fallen into the ftream, were carried down as far as its rapidity would allow, and then depofited wherefoever its force abated; which produced two forts of new lands; the one form'd in fome lower part of the river's courfe, that was larger or deeper; which operation tended to give a regularity to its bed: the others oppofite to the crumbling cliffs, when the river, in its effort to demolish them, fenfibly gained fpace on their fide. These operations have been fo much the more rapid, as the banks attached had lefs elevation, or oppofed lefs refiftance; and they continue in many places. I fhall not particularly ftop to confider the cafe, where the rivers have found natural channels without any great windings, and where thus they have only had to acquire a regular declivity: for though, in forming their bed there, they have excavated the ground in fome parts of their course, and thereby form'd abrupt banks at their two fides, the progrefs of those effects I am about to fpeak of, will apply to thefe, as well as to their more complicated cafes produced by obitacles.

49. The rivers have produced cliffs on one of their fides, only in the parts where the bent they received was at first too short; they

then tended to acquire an easier curve, by attacking the obstacles. While thus they occafioned confiderable demolitions, they rofe by the refiftance of the obftacles, and the violence of their fall from thence into fome lower part, or of their recoil, made them carry down, or depofit on the other fhore, all the rubbish fallen from the cliffs: but when, by thefe operations, their windings became lefs abrupt, and their declivity more uniform, the larger materials began to remain at the feet of the cliffs; and there gradually raised a bank, which ferved to diminish the force of the current. When this is once produced, the materials that continue to fall from these steep banks, form, by degrees, at their feet, a ftrand, on which the river no longer rifes, except at the times of a flood: the new falls of materials then extend, and elevate this ftrand; and the cliff itfelf, which retreats further and further by its demolition, at length gets beyond the reach of the current: it then becomes reduced to a fupe by the action of external causes, and vegetation fixes it. During thefe operations, the materials that the place attacked fupplies, depofit themselves either on the oppofite fide, or in fome further part in the courfe of the river, where the waters having more space to flow in, lofe their rapidity. There at firft all the materials arrived; then fucceffively the larger remained behind: by degrees, the extent and height of the new-lands thus formed increased by mere fand, depo fited over them in times of floods: this alfo gradually decreased, and the rivers carried down fand, only in great floods: and at length, by the removal of every obftacle fufceptible of giving way in the course of a river, the time comes, when, by being confined in a regular channel, of which the new-lands it has formed make a part, it only rifes and falls, in the greatest floods, between Smooth banks, covered and fixed by vegetation.

50, Such have been, and ftill are, in many places, the real opera. tions of running waters, which fome Geologifts, on the fuppofition that they have been attacking our continents during an indefinite number of ages, confidered as having produced all the finuofities at their furface. As foon as the rains began to fall on our continents, their waters collected in the channels that the declivity and the finuofities of their surface offered them; and when they once had taken those natural and inevitable roads, they could not change them, but by finking more and more between thofe tracts of ground which, from the beginning, were more elevated than they; fo that the rivers could not fift their courfe, as thofe Geologifts fuppofed, except in fome plains lying very low, and abfolutely horizontal, or at the bottom of large vallies, which they had before levelled by carrying rubbish thither from the higher grounds. The firft determined channels of the running waters, were the bottom of the chafms, and other finuofities, of the mass of trata formed by the fea, of which the nature and anterior catastrophes are marked by very decifive characters; in fuch a manner, that we may always determine, with refpect to places where the rivers have produced real alterations, how they must have been at the birth of our continents; and what are the alterations produced fince that time by those running waters; which alterations have most decided characters.

51. The places where it is eafieft to ftudy the Hiftory of rivers, are in their windings, produced by lands which have obliged them to al

ter

ter their courfe, and have been fufceptible of demolition. There we difcover the point where the attack has begun, and the excavation that has been made: we find befides, either lower down, or oppofite to the excavated ground, if it was not very high, the materials that have fallen from it: these materials have first levelled the bed of the river, and then formed new-lands, always diftinct from the original foil, both in their regular inclination towards the stream, and in the nature of their compofition; they have no coherence, and the materials which compofe them increase in fize from top to bottom. Thefe oppofite operations, are in many places terminated: then the lands formerly attacked, as well as the new-lands formed of their ruins, undergo no more fenfible alterations, and the river flows quietly by both: but in other places these two operations, always coincident, continue in various degrees, and are more or lefs diftant from their termination. Now, as near the mouths of rivers, where they empty themselves into the fea, and where they depofit all the mud they have brought down with them from their fource; monuments and traditions are found, which mark feveral aras in the progrefs of the new-lands they have thus produced; fo we find, in many parts of the former courfe of rivers, monuments which agree with thefe in the fame chronometrical Scale: I fhall cite but one example, but that a very remarkable one, fince the monuments are of the fame nature, both at the mouth of a great river, and in a particular part of its former course.

52. I fpeak of the Rhine, with refpect to which I have faid above, that the Romans had built a custom-house near the mouth of one of its branches, the ruins of which, (as well as a monument relating to Agrippina) have been found in the fand-bank, which has from that time choaked this arm, and fo completely, that fand-hills have been raised there by the wind, as on the rest of the coast of Holland. I now am about to point out another Roman monument of the fame age; in one of the accumulations of materials, formed by the fame river, very far from the sea, attended with circumftances that will ferve to confirm the whole procefs I have hitherto traced in the mountains, vallies, and plains.

53. The Rhine, before it joins the Mofelle, flows a long way through a valley, whofe fides were originally very steep and fhattered; but at prefent they are foftened by irregular bands, which, in a great part, are covered with vegetation. During the operations which have at length brought thefe confufed cliffs almost to an entire ftate of repofe, their fragments have formed, along the prefent course of the river, a ftrand more or lefs wide, which shuts it in, and on which the rubbish that ftill falls from fome of the fteep parts, accumulates. The place where the two rivers unite, is an open space where ftands the town of Coblentz; and thither, while the fides of the upper vallies crumble down rapidly, thefe rivers, much agitated thereabouts by the obftructions in their beds, have brought down very large fragments of ftones: but by little and little they have become more tranquil; the materials they carried down have been fucceffively (maller; at laft they have been nothing but sand, and at this day, flowing between the banks they have themfelves formed, these rivers overflow them but very rarely. It is in one of these accumulations of materials that the hiftory of the Rhine is particularly to be traced.

54. I pafs'd through Coblentz, in 1778, at the time they were laying the foundations of the new Electoral Palace: the late M. LA

ROCHE,

ROCHE, chancellor to the elector, prefided over these works, and he invited me to accompany him there, that he might fhow me fome very interefting things. A very deep excavation had been made in the mafs of accumulated materials, which there form one of the banks of the Rhine, and M. LA ROCHE, showed me on one of the fides of this hollow, the section of a kind of well, many of which he told me had been found in the space thus excavated; they contained urns with afhes and bones, divers kinds of fepulchral attributes, after the manner of with the Romans, and fome legion ftones: a circumftance which agrees the remains of Roman camps, found in many parts of the valley. Here then is a fixed epoch, in the hiftory of this accumulaton of rubbifh carried down by the Rhine; and now we are to examine the natural monuments of its progrefs, connected with that Epoch.

55. The bottom of this excavation, was compofed of large flones worn by attrition; to thefe fucceeded (as obferved in the lateral fections) gravel, diminishing in fize from the bottom upwards: it was in this gravel, to which fand had begun to fucceed, that the Romans had dug the wells I have been mentioning: fince that time the top of thefe wells has been covered by eight feet of pure fand; and at this day, the Rhine, having fettled its bed, but feldom rifes to this height. The time when the Romans carried on war with the Germans, and pushed their conquefts as far as to the Batavians, is known; and thus it is, that we have two of their monuments of the fame period; the one buried by the fediments of the Rhine, in a part of its inland course, the other in the fediments both of the river and the fea, at one of its mouths. Now the place which these Roman monuments occupy in this mafs of transported matters, (whofe tranfportation could only have begun at the birth of our continents,) transforms these biftorical documents into geological monuments, belonging to a particular and very extenfive clafs; it is an example of the chronometers to be found in the course of all rivers, which agree with each other, and with every other kind, and prevent our referring the origin of our continents to an epoch more remote than that of the deluge in Sacred Hiftory.

56. The whole that I have brought together in this letter, to prove, in different ways, this great geological fact, is only a fketch of what I have already published on this fubject, in my Letters on the Hiftory of the earth and of man; and the attention of naturalifts being at prefent fixed on this phyfical chronology, it will in the end, obliterate all the fabulous traditions, and the fyftems founded on them. I have already cited M. DE SAUSSURE, and M. DE DOLOMIEU, for fome recent facts, and I cannot better conclude on this fubject, than with the following paffage from the latter. (Journ, de Phyfique, Jan. 1752.) “I will defend," fays he, "a truth which appears to me inconteftableand of which, I find proofs in every page of hiftory, as well as in what it naturally should be referred to, the facts vifible in nature.—That the prefent ftate of our continents is not ancient-that it is no long time fince they have been given to the dominion of man! !".

After having proved that we cannot refer the birth of our continents, to a period more diftant than that at which the Mofaic Hiftory fixes the deluge, I have now to fhow, that the revolution, by which, according to every fact of geology, our continents had their origin, muft have been this very event: this I fhall do in my next letter.

ACKNOW

We are obliged to Cato for the Continuance of his Favour. With respect to the prefent Subject on which he addreffes us, we inform him, that it is contrary to our Rule to notice periodical Works till they obtain the Shape of a Volume; to which, probably, the paltry Publication he mentions will never attain. Should it happen otherwife, we shall be glad of his further communication: but we must beg him to drop the anonymous mode.

A. M. may be affured, that we fhall turn a vigilant eye towards the Publication he mentions. But we ftill perfift in. thinking a Review of Politics inconfiftent with the Occupation of literary Men, and in our Cafe, infra dignitatem; as wearing the Appearance of catching at an Extenfion of Sale, which we have no occafion to do, and could not condefcend to, were it neceffary.

A. X. may depend upon our Attention to his Request.

We will certainly attend alfo to the Production recommended to our Notice by A Conftant Reader.

We have not yet had an Opportunity of enquiring into the Fact stated by P. R.: But we have no doubt that what he tells us concerning the general Merits of the late Dr. Ufsher, of the University of Dublin, is ftrictly juft. If, on due Enquiry, we find Reason to believe that P. R. is not mistaken about the Invention he attributes to that excellent Aftronomer, we shall be very ready to bear our public Teftimony in his Favour.

Several other Correfpondents must be reminded, that we cannot infert anonymous Communications.

ERRATUM.

In our laft Number, p. 388, Acarnanes is printed erroneously for Acharnenfes. The difference between AXAPNA, the Attic Borough, and AKAPNANIA, with their respective Derivatives, Axapers, Axapraves, &c. was perfectly prefent to our Minds when we wrote that Article, and the Comedy of Ariftophanes, named from the former, actually open before us, but, by an accidental overfight, the error was made in the Prefs, and fuffered to continue. DOMESTIC