1936.] 



FARMERS' REGISTER. 



033 



The large proportion of Muriatic soda shown to 

 be present in the above instance, is an interesting 

 fact particularly when taken in connection with 

 the locality whence the water was procured. For, 

 it cannot be considered probable that this ingre- 

 dient could be derived from the neighboring river or 

 the bay, as this would imply an extent of filtration 

 in an horizontal and upward direction, which it 

 would be unphilosophical to admit. It is rather, as 

 I conceive, to be looked upon as referrible to the 

 former impregnation of saline matter derived from 

 the waters of the ocean, beneath which nearly 

 all the strata of this region were originally depo- 

 sited. 



Nature and varieties of the Miocene Shell Marl. 



In the general description of the district of 

 which we are now treating, a detailed account has 

 been given of the arrangement of the beds of fos- 

 sils as they occur in nearly all the localities which 

 have been examined, accompanied by an enume- 

 ration of the principle shells, an account of the 

 materials in which they are embedded, and with 

 which they are associated in contiguous strata. 

 We are next to consider the materials of these 

 beds in relalion to their agricultural importance, 

 and to exhibit the relative value of the marl of 

 different localities as illustrated by chemical ex- 

 amination. A large proportion of the matter of 

 all shells consists of carbonate of I me. Hence 

 they are nearly identical in composition with lime- 

 stone, chalk and marble. To this ingredient, in 

 whatever form it may be applied to the soil, gen- 

 eral experience has ascribed a very high degree of 

 fertilizing power, and hence, in the application of 

 all the varieties of calcareous marl, we are guided 

 chiefly by the proportion of the carbonate which 

 they contain, as determined by chemical analysis. 

 It should not, however, be inferred, that the va- 

 rious mixtures of earths and other substances 

 with which the calcareous matter is usually asso- 

 sociated, are devoid of useful action when applied 

 to land. The experience of agriculturists is cer- 

 tainly inconsistent with such an opinion, though 

 it has most clearly evinced the powerful efficacy 

 of calcareous manures. The invaluable publica- 

 tions of the editor of the Farmers' Register by 

 directing the attention of farmers tothe employment 

 of the shell marl with which nature has supplied 

 them in such rich abundance, have led so exten- 

 sively to the application of this manure, and have 

 produced so general a conviction of its fertilizing 

 effects as to render it unnecessary in this place to 

 introduce either facts or arguments in its favor. 

 To the valuable practical suggestions of this gen- 

 tleman, contained in the "Calcareous Manures" 

 and other publications, we are indebted for much 

 of the amelioration which has taken place in the 

 agriculture of eastern Virginia, and I therefore 

 cannot do better, in alluding to this branch of my 

 subject, than to recommend these works to the 

 earnest perusal of all who are interested in ad- 

 vancing the prosperity of that portion of the state. 



But although the richness of the marl is mainly 

 dependent on the proportion of its calcareous con- 

 tents, it is also largely influenced by the nature 

 and condition of the shells of which it is composed. 

 It is well known that the recent oyster shell, espe- 

 cially in its unbroken state, is far less immediate 



Vol. HI— 80 



and powerful in its action upon land than the fria- 

 ble and pulverulent shells, of which many of the 

 most valuable marl beds are principally made up. 

 Yet in the composition of the recent oyster shell, 

 the amount of calcareous ingredient is nearly as 

 ixreat as in the richest marl beds which we have 

 examined. According to an analysis which I 

 made some years ago, 100 grains of this material 

 were found to contain 



Carbonate of lime, 95.18 grs. 



Phosphate of lime, 1.88 



Silex (probably accidental,) 0.40 

 Water, 1.62 



Insoluble animal matter, 0.45 

 Loss, &c. 0.45 



100.00 

 [Vide Farm. Jieg., Vol. 1. and Sdlimaii's Jour. 



These remarks being also applicable to some 

 species of fossil shells, it becomes necessary to a 

 judicious selection of the marl, to give some atten- 

 tion to the different nature of the shelis contained 

 in the several varieties of marls offered to our 

 choice. 



Kinds of shells which are least likely to be useful.. 



The fossil oyster and scallop shells, (Ostrea Vir- 

 ginica and Pec-ten,) of which many marl beds are 

 almost exclusively composed, are generally found 

 in a nearly unaltered state. Comparing the com- 

 position ol' these shells, as ascertained by my anal- 

 ysis, with that of the recent shells, the animal 

 which, though small in quantify, seems to act 

 powerfully as a cement for the other materials, was: 

 found to have been retained in almost undiminish- 

 ed proportion; and thus these shells are scarcely 

 better fitted for the soil, than recent ones of the 

 same species. It is to the animal matter retained 

 by the fossil scallops that we are to ascribe the 

 dark color which they assume when burnt for 

 lime. Whatever miu'lit be the usefulness of this 

 ingredient, if mingled with the soil, it here ope- 

 rates to impair the value of the shell as calca- 

 reous manure by the insoluble character it imparts 

 to the materials it holds together. Next in tardi- 

 ness of disintegration, and in consequent ineffi- 

 ciency as a manure, may be enumerated the large 

 clam, (Venus mercenaria,) and an oblong smooth 

 flat shell, (Crassatella.) These, however, have 

 evidently undergone a change, which prepares 

 them for yielding, more readiiy than the ibrmer, 

 to the agencies of the seasons. Most of the other 

 species, though entire when first found, soon fall 

 to pieces and spread their fertilizing fragments 

 through the soil. There is, however, even among 

 them some room for choice — and this leads us to 

 consider the 



Kinds of shells luhich are 7>wst suited for the pur- 

 pose <f marling. 



The Chama, formerly mentioned as occurring 

 in extensive beds in some portions of the Miocene, 

 and existing in considerable proportion in nearly 

 all the iossil strata, forms the principal component 

 of some of the most productive marls. This is a 

 small two-valved shell of rugged exterior, which 

 readily breaks to pieces in the ground, and is 



