692 



FARMERS' REGISTER 



[No. 11 



increases with its depth; commonly its shade be- 

 comes more near to white, as the proportion of car- 

 bonate of lime is augmented. 



Marl may be more or less compact, and retain 

 more or less water, according as the argil which it 

 contains encloses more or less of sand — or ofsand in 

 grains more or less fine: for, according to the expe- 

 riments of Schubler and of M. de Gasparin, fine 

 sand retains almost as much water, and gives to 

 its compounds almost as much tenacity, as argil 

 does. 



The color of marl is very variable; however, 

 stony marl is almost always white. Earthy marl, 

 though taking all colors, is most often gray. 



These differences of composition and of appear- 

 ance, have caused marl to be divided into argillace- 

 ous (or clayey,) sandy, and stony marl — terms a 

 little vague it is true, but which, however, are use- 

 ful in practice. 



Marl seems to be, in most cases, a formation of 

 fresh water; a great number of marls, of various 

 kinds, colors, and composition, in A in, Saone and 

 Loire, Isere, Provence and the stony marls of 

 Yonne,have presented to us a great variety of shells, 

 which have been recognized as belonging to fresh 

 water formations.* 



* As the "marl" described above, though agreeing 

 in its most important chemical and fertilizing proper- 

 ties with what is called marl in Virginia, is yet very 

 different in appearance and in its localities, it may be 

 useful to add to this account, something from the more 

 full account given in the original Essai stir la marne. 



"Marl is found in countries of the tertiary formation, 

 and particularly in the basins formed by calcareous 

 chains, and most often at a little distance from the 

 mountains. It is placed commonly upon the slopes of 

 hills of no great elevation, [collines,'] in hollows, or in 

 layers, either horizontal or inclined. It is more rarely 

 found in the plain, and when met with there, it is 

 placed at a much greater depth in the earth. 



"There has been much discussion as to the origin of 

 marl; but it shows itself under aspects so different, in 

 forms and in texture so varied, that it has been impos- 

 sible to assign to it a common origin." 



After describing the several kinds of marl, as in the 

 text above, though more at length, the author adds — 



"Lastly, we have to mention shell marl— which is 

 again divided into two classes, according as the re- 

 mains which it contains, are derived from the sea, or 

 from rivers. This marl is, of all, tne most precious: it 

 would seem, more than the others, to contain the prin- 

 ciples of [alimentary] manure, and perhaps, some re- 

 mains of parts not yet destroyed of animal principles. 



"We shall class as shell marl the crag, which in Suf- 

 folk, and combined with dung, renews without cessa- 

 tion the fertility of the country which uses it; the falun, 

 which in Touraine fertilizes whole cantons; and in 

 short, numbers of other beds of shells not bound to- 

 gether by a cement, and which under different names in 

 France, are used as manure with much advantage." 



This is precisely the description of the marl of Low- 

 er Virginia, and this kind the author never means when 

 he speaks elsewhere of marl simply. 



"It appears that the examination of the shells whi^n 

 are often met with in the earthy marls, may offe 

 geologists valuable information upon the formatio 

 marls themselves, and upon that of the countrfes i 

 which they are found." The following known shells, are 

 afterwards named in a catalogue, which will be given 



Searching for marl. 



The importance of marl in agriculture ought to 

 cause it to be sought for wherever it may be of use, 

 and almost always it is found near the surface of 

 the ground. The plants, colt's foot (j.ussilagc,'] 

 rest-harrow [F ononis,'] sage, yellow clover, bram- 

 bles, thistles, cow wheat [melampijre,] commonly 

 indicate the soils under which marl is found at lit- 

 tle depth. The digging of ditches, and of wells, 

 often expose it; more often it is lbund in grubbing 

 upon slopes. Beds of sand also announce its pre- 

 sence, as they almost always cover or underlie the 

 marl. 



If none of these signs indicate it, marl may be 

 sought by boring in the lower parts of the land. 

 But deep borings require heavy expenses: the 

 drawing out of the marl which ihey might disco- 

 ver would be effected only at great cost — and gen- 

 erally, springs of water would be met with, which 

 wouid oppose all economical labor. However, 

 when water does not injure the work, drawing 

 marl from great depths is much more economical 

 than the transportation from distant places. Ex- 

 iracting marl from great depths is not a novelty in 

 France 7 . Pliny speaks of marl which was drawn, 

 in Gaul, from more than 100 feet in depth; in Nor- 

 mandy, it is still obtained in this manner; and near 

 Lisieux, some marl-pits are more than 70 brasses, 



in an abridged form. The names of the shells, may pos- 

 sibly furnish useful indications to those investigators 

 who are better informed on this part of the subject. Of 

 those marked with a star (*) similar living species are 

 found still in the country. 



In a marl sent from St. Trivier — yellowish, compact, 

 of homogeneous appearance, and coming to pieces 

 finely and easily in water — 



Land shell — Turbo elegans. 



River shells — Helix fasicularis, Helix vivipara, * He- 

 lix tentacula, * Mya Pictorum. 



In a marl from Cuiseaux, Saone et Loire — 



River shell — Melanopside (of Lamarck.) 



In a marl from Leugny, in Yonne — 



Land shells — * Chassilie ridce (of Lamark, and Dra- 

 parnaud,) * Helix lubrica. 



In a marl from St. Priest in Dauphiny — earthy, yel- 

 lowish, very easy to melt in water— r ..< 



Land shell — * Ambrelte alongee (of Lamark andDra- 

 parnaud,) * Helix hispida. 



In an analogous formation of marl, in the basin of 

 the Rhone, between Meximieux and Montluel, the 

 Helix striae, a land species, is found in great abundance. 



M. Puvis' states that among these, and among all the 

 species of shells found in the marls of the basins of the 

 three great rivers, Saone, Rhone and Yonne, there are 

 no remains of sea shells. All seem to have been formed 

 under fresh water. "But (he continues) as these 

 marls contain land shells, often in great abundance, we 

 must conclude, that the revolution which heaped up 

 the marls, has been preceded by a time in which the 

 land was not covered by water, in which the earth, pro- 

 ducing vegetables, permitted the multiplication of the 

 species of land shells which were found in these marls." 

 Essai stir la marne, p. 8, top. 24. 





