rS36.] 



FARMERS' REGISTER. 



203 



our country, (as described concisely in Essay on Cal. 

 Man. p. 40, 2d Ed.) and tlience supposed that there 

 had been a similarity of geological i'ormation, different 

 from that of the lower and more fertile lands intersect- 

 ing this steril region, and different from that of any 

 other region ever heard of, until we recently met with 

 the writings of M. Puvis, and his description of pre- 

 cisely similar lands in France. We are rejoiced to be 

 enabled to call his support to the aid of improvement 

 in Virginia and other Atlantic States: for all that he 

 says, in this article, is as applicable to our country as 

 to France. Whether his geological views are plausible 

 ox not, we are not qualified to decide: but at any rate, 

 tliey, and the facts by which thev are supported, are 

 curious and interesting. 



The classifications of soils by writers on aajri- 

 culture seem to have been hitherto of little utihty. 

 Till now they iiave aimed to class them by means 

 of their texture, or diHerent degrees of consisten- 

 cy; and this method has brought together soils 

 different in nature, properties and composition. 

 Hence it has resulted that the classification, in- 

 stead of simplifying matters has only rendered 

 them more complicated; and in this instance, as in 

 some others, science, by a classification at variance 

 with nature, has retarded, rather than advanced 

 practice, and has introduced a vexatious confusion 

 into agricultural works and theories. This serious 

 inconvenience would not have occurred if lessons 

 had been taken Irom practice in this question. 

 Every where experience has taught the husband- 

 man to divide the soil into two classes, distinct in 

 their nature, their composition, their properties 

 and productions: it is this unscientific (empiriquc) 

 classification which should have been followed; 

 and then we sliould not have been lost among the 

 English "Zoaws" of which we cannot ascertain the 

 exact quality, now the "free lands," (tcrres f ran- 

 ches,) nor "iat clays;" (hits gras,) of our French 

 writers, wliich also occasion misinterpretations in 

 each country. 



The great author of all things, in his supreme 

 wisdom has fortunatefy varied the comparison of 

 soils but little. AiTiong the vast multitude of sim- 

 ple substance ot which the globe is composed, he 

 has scarcely admitted more than three to form its 

 surface — that part destined to support its inhabi- 

 tants: these substances are siiex, alumine, and 

 Time. A greater number of component parts, by 

 diversifying the nature of the soil, would have 

 made agriculture much more complicated — and it 

 is already, in the actual state of things, so difficult 

 an art! If it had been necessary to practice hus- 

 bandry upon a soil composed of numerous ele- 

 ments, it would have been almos't entirely above 

 human intelligence. 



Among these three earths, the two first, silex 

 and alumine, form almost the whole mass of the 

 upper stratum, and exclusively compose more than 

 half of it. The silex is found in the form of sand, 

 and the alumine is scarcely ever met with alone, 

 but it exists in the soil under the name of argil [pure 

 clay] day, always mixed, or rather combined with 

 particles of silex very minutely reduced. 



When lime, or rather the carbonate of lime, is 

 found mixed in a greater or less proportion with 

 the two first earths, it modifies their nature 

 in whatever quantity it may be found mixed with 



them: the compound then lakes the name of cal- 

 careous soil, and its properties are changed in a 

 remarkable manner. 



Sometimes the lime is mixed with a little mag- 

 nesia, which then changes all the characters of the 

 calcareous soil and most frequently renders it barren. 

 With these three principal constituents there is 

 fijund mixed more or less of vegetable mould, (hu- 

 nnis,) the decomposed remnants of preceding ve- 

 getation, or additions made by man to increase 

 fertility; and, finally, a small portion of oxide of 

 iron is very often met with, which does not seem 

 to act an important part in vegetation. 



Practical agriculture has learned in each country 

 1o divide the soil into silicioiis, and calcareous lands.* 

 In Ain, Saone-el-Loire, and Jura, and in a great 

 l)art of France, the argilo-silicious land, (^terre ar- 

 gilo-silicieuse) bears the name of terre blanche 

 and the calcareous lands receive names wliich dis- 

 IniL'uish them from it completely; in the south the 

 argilo-siliceous lands are called boulbenses, and the 

 calcareous lands tei-res fortes, in Yonne they are 

 distinguished as terre de puisage and fortes terres, 

 in Aveyron the one has the name of segallas, and 

 the other that of causses; in Berry and the Gatinais 

 the first is called tcrres de Sologne, in Belgium and 

 the north it is called terres a bois, terres elytres. 

 In fine, practice has every where given a distin- 

 guishing name to this nature of soils, which every 

 where offers the same composition, the same pro- 

 perties, the same productions and the same diffi- 

 culties in its cultivation. 



It is this classification, this distinction of prac- 

 tice that 1 propose to examine particularly. So 

 long ago as 1811, struck with these two great na- 

 tural and practical divisions, I published a me- 

 moir on this subject. Since then I have felt more 

 and more the great necessity of it, and my pre- 

 sent work, which is the study of the first class of 

 soil, of the soils composed of silex and argil will 

 be, in some sort, a developement of facts in sup- 

 port of my work of 1811. Hereafter we shall be able 

 to return to ihe study of calcareous soils. 



Our subject will lead us to some details of agri- 

 cultural geology, a science yet in its birth, for which 

 as we proceed, we shall collect some materials. 



I. Tlie soil of which we are going to speak is 

 not to be confounded with the granitic or schistous 

 soils which cover the most elevated parts of the 

 globe. These last soils offer indeed an analogy of 

 composition and productions with the former; they 

 are also composed of alumine and silex — but they 

 abound in granitic or schistous fragments of various 

 magnitudes, which are not met with in like man- 

 ner in the nrmlo-siliciouB plateaux; they produce, as 

 these last, the heath and broom, but the fern does 

 not grow abundantly on them. Their formation 

 is not the same, the exterior characteristics and 

 the sub-soils are different; the granitic or schistous 

 soils seem to have been owing to decompositions 

 of granite or schist on the same spots by meteoric 

 influence; at other times they have been produced 

 by the movement of partial waters in the interior 

 of basins. 



* Here and elsewhere the author uses the term "sili- 

 cious soils" in contra-distlnction from "calcareous" — or 

 to designate soils which are not at all calcareous. We 

 have elsewhere used the term "acid soils" for the same 

 seneral class. — ^Ed. Far. Reg. 



