206 



FARMERS' REGISTER. 



FNo. 4 



they approaches tlie sea, and conpequenlly have 

 rendered the alluvions more stiff, more clayey. 

 Thus the soil of the horders of the Seine which 

 often shows little stitihess at Paris, acquires more 

 as it approaches the sea: und in like manner the lit- 

 toral soil of the three rivers, the Riione, the Saone, 

 and the Aisne, is lighter before their confluence, 

 than that of the Rhone in Comtat, and that of 

 Comtat is less clayey than that of the great plain 

 of Aries: these facts are explained in the same 

 manner as the preceding. 



XI. Finding myself involved in the great ques- 

 tions of the formation of soils, I shall not hesitate, 

 at the risk of digressing from my subject to collect 

 here many important facts in agricultural geology. 



The argilo-silicious deposite has been very evi- 

 dently the last of the great deposites which have 

 covered vast surfaces: it is, in some sort, the last 

 phasis, or general movement of waters, on the 

 surface of the earth; but since then, partial revo- 

 lutions seem to have taken place in the basins of 

 large and small rivers; there are even some to 

 which we seem able to assign an era, and which 

 do not go beyond the historical ages. Thus many 

 positive and very remarkable facts may induce an 

 opinion that in the basin of the Rhone a great 

 movement of waters must have taken place 

 since the establishment of the Roman dommioh in 

 this country. When wells are dug at Marseilles, 

 water is found under a stratum of gravel about 20 

 feet thick, at its junction with another flirmation on 

 which wc meet with traces of habitation, roads, 

 Roman, Phoenician and Gallic medals. This level 

 of the soil has then been inhabited, two thousand 

 years or more ago, and consequently the stratum 

 of gravel more than 20 feel thick which covers 

 these parts of the basin has been brought into 

 them since, by a movement of vvaters which no 

 historical recollection recals. 



But if we remark further that in ascending the 

 basin of the Rhone to Aries, to Orange and V^a- 

 lence, to Nimcs, to Lyons, the traces of Roman 

 inhabitation are evey where covered with a stra- 

 tum of gravel many feet thick — that at Bourg, 

 situated in the same basin, are found medals, in- 

 struments of a contemporary date and of tlie same 

 sort as those met with at Marseilles, and every 

 thing wliich characterizes an ancient level of ha- 

 bitation between two strata of gravel analogous 

 to those which cover them elsewhere — we shall 

 have good reason to believe that the stratum above 

 the medals which have been found, must be owing 

 to the one same revolution, which consequently 

 must have changed the whole face of the lower 

 part of the basin of the Rhone. 



This stratum at Marseilles, and in the greater 

 part of the places where it occurs, cannot be owing 

 to the Tuins of habitation, to the rubbish of destruc- 

 tion, which raises the inhabited surface in popu- 

 lous cities; for the traces of habitation, the medals, 

 the roads, mould (humus) bricks and pottery, in 

 angular pieces, would be found througiiout the 

 whole thickness of the stratum, whereas this is 

 composed without mixture o( r->l!ed pebbles of si- 

 licious gravel of the same kind, covering calca- 

 reous gravels disposed in horizontal strata, identi- 

 cal in thickness and in composition, which could 

 be owing only to a natural formation deposited 

 from the bosom of the waters. 



But still farther traces of this inundation are 

 found. At the junction of the basins of the Ainand 



the Rhone, there exists a great plain which bears 

 the name of Valbonne, (rullis Bona;) a name 

 evidently given by the Romans, and of which the 

 soil is now composed of an arid stratum of silicious 

 gravel like that which is found all along the basin 

 of the Rhone; but we should consider as certain, 

 that this stratum did not cover the valley when it 

 received the name of VdUis Bona; it may then 

 be believed, tjiat the alluvion of good quality 

 which covered this valley, was carried off by the 

 great flood which has thrown over a great part of 

 the surfiice of this large basin, all those increments 

 of gravel which have covered and devastated the 

 inhabited surface. In support of this conjecture, 

 we find in Bas-Bugey at Mcximieux, and in Dau- 

 phiny, at Saint Priest, opposite the plain in ques- 

 tion, a stratum of calcareous soil of good (}uality, 

 which often rises many feet above the alluvion of 

 gravel, this stratum, which at several points bears 

 traces of having been torn away, rose, it may be 

 believed, above the boi\lers of the Ain and the 

 Rhone; it covered, consequently, the plain between 

 Meximieux and Montluel, and gave occasion to 

 its name of ValUs Bona, which was preserved to 

 it after the waters had deprived it of its qualities. 

 An aqueous revolution then has taken place in the 

 basin of the Rhone; this revolution must have 

 been subsequeiU to the establishment of the Ro- 

 man power, and to this revolution the stratum of 

 silicious gravel succeeded, which from the bor- 

 ders of the lake of Geneva, to those of the sea, co- 

 vers such vast extents. 



We shall not continue farther the discussion of 

 this important question of agricultural geology, for 

 fear of exceeding the proper limits of this journal. 



X!i. In all movements of great waters which 

 have taken place, each basin of a river has formed 

 a new upper stratum which has become the vege- 

 table stratum (or surface soil;) and this is distin- 

 guished by shades of formal ion which are pecu- 

 liar to itsclfj and which it has received from the 

 fragments of the mountains which border upon it, 

 from those brought by the waters of its confluents, 

 mixed with the great general deposites. Thus are 

 explained those analogies of soil and of formations 

 which are found throughout the whole extent of 

 any one basiU; and in the secondary basins them- 

 selves. 



We have designedly gone back to the origin of 

 these analogies of soil, that we might recur to an 

 important idea in agricirltui-e. It is this: that the 

 formations in any one basin being composed of the 

 same fragments, and owing to the same revolu- 

 tions, the soil of these basins presents throughout 

 their whole extent a great analogy, and conse- 

 quently, the practices of agriculture which have 

 succeeded in one point, may be aj)plied, the diffe- 

 rence of climates excepted, to the analogous for- 

 mations; agriculture perfected on some ])oints of a 

 basm, may give lessons almost certain for its 

 whole extent.* Thus the study of agriculture, to 



*It may not be useless to all readers to say, that by 

 the "basin" of a river, the author does not mean mere- 

 ly the valley or lower lands through wliich it flows, 

 but the whole area, high and low, which lies within, 

 or is intersected by, all the tributary streams of the 

 river. Thus the basin of the Mississippi takes in tlie 

 immense area from the summits of the Rocky Moun- 

 tains to those of the Alleghany. — Ed. 



