714 



FARMERS' REGISTER. 



[No. 12 



chalky marls yielded a proportion more than twice 

 as great. 



In jreneral, the upper beds of the meiocene in 

 this district, were /bund to be destitute of (bssils, 

 thouijh lull of their casts and irnpres.-jnns. These 

 strata consisting for the most part of light colored 

 sandy clays, trequently of great depth, are distin- 

 guished by a sulphureous smell, and often by an 

 acid and styptic flavor. They rarely contain an 

 appreciable amount of carbonate of lime, but are 

 impregnated with sulphate of lime (gypsum,) 

 together with sulphate of iron, (copperas,) sul- 

 phate of alumina, sulphur and sometimes even a 

 sensible amount of sulphate of magnesia (I^^psom 

 salts.) The acidity of these clays is often snlTi- 

 cient to make a pungent impression on the tongue, 

 and their sulphur is distinctly recognized by the 

 characteristic odor exhaled, especially when they 

 are heated. In many localities, as in the Rappa- 

 hannock cliffs in Richmond county, the gypsum 

 occurs in crystals of sufficient masrnitude to be 

 separated by the fin<iers, and sometimes in the at- 

 tractive form of transparent selcniie; but its more 

 usual condition, is that of delicate silken crj'stals 

 distributed throuirh the mass, and visible only upon 

 close and attentive inspection. 



Numerous s|)ecimens, taken from strata of this 

 kind ill various parts of the Neck, presented a 

 great siinilariiy of composilion, though not with- 

 out much variation in the proportion of the gyp- 

 sum and other ingredients which they contained, 

 and like results were obtained from the analysis ol' 

 the overlying and once fbssiliftjrous beds in other 

 places, where the meiocene marl occurs. The 

 cause of the extensive destruction of shelly matter 

 once imbedded in tliriss clays, was clearly traced 

 to the sulphuric acid, oriffina'ing in the decompo- 

 sition of sulphuret of iron, which permeating the 

 beds of marl, converted the carbonate into sul- 

 phate of lime. This being in part retained, formed 

 the crystals of gypsum now discovered in these 

 strata — at the same time, that by the decompo- 

 sition of the sulphuret, the sulphate of iron and 

 other ingretlients above noticed were brought to 

 light; and the overlying layer of l(?rruginous rock, 

 or clay, most probably owes its origin to the same 

 source. 



The presence of gypsum in these beds susr- 

 gests the interesting inquiry as to. how iar they 

 may become available in the agriculture ol" this 

 and other regions, sinnlarly situated. Upon this 

 point, I shall embrace the present opportunity lor 

 a lew brief remarks. Where they contain a con- 

 siderable amount of this ingredient, say 10 per 

 cent., and are impregnated with no injurious or 

 counteracting agent, no doubt can exist as to their 

 beneficial influence upon the soil ; and in such 

 cases, besides the peculiar ameliorating effect of 

 the gypsum, they would impart the hirther advan- 

 tage of an improvement in the texture of the land. 

 But as in most instances, the proportion of gyp- 

 sum does not exceed two per cent., and as it is 

 blended with the other sulphates, as well as li-ee 

 sulphuric acid and sulphur, ingredients which in 

 considerable quantity are known to be destructive 

 lo vegetation, it would naturally be inferred, that 

 such materials, if not inert, must be actively inju- 

 rious in their effects upon the soil. Experience 

 too, has seemeil to give authority to this opinion, 

 since when applied to the land, as in some cases 

 these materials have been, in considerable quanti- 



ties, a diminution, or even temporary loss of pro- 

 ductiveness has ensued. Slill, however, it should 

 be remarked, that experiments thus roughly made, 

 by no means justify any confident conclusion on 

 the subject. The effect of such substances on 

 ve<retation must greatly depend on the quaniity in 

 wiiich they are applied. When prodiirally spread 

 over the land, there can be no doubt that they in- 

 flict serious, though by no n)eans irreparable injury. 

 Such also is known to be the consequence of a 

 redundant application of the ordinary' calcareous 

 manun>s. But observation would seem to prove 

 that, when sparingly employed, the materials re- 

 ferred to, are productive of a very decitied im- 

 provement. ' In many parts of lower A'irginia, 

 these gy|)seous and acidulated clays applied un- 

 der the impression that they contained a useful 

 [)roportion of green sand, have been found to im- 

 part new and surprising energy to the soil. 



Without enterino; upon the obscure question of 

 the modus operandi of mineral substances, includ- 

 ing calcareous maimres, upon plants, we cannot 

 doubt, that in part, at least, tlieir influence is that 

 of directly stimulating the vital organs concerned 

 in vegetable growth — nor can we avoid believing, 

 that with i)lants, as with animals, the number of 

 substances adapted to produce this eflect is far 

 fi-om being restricted to the few materials most 

 commonly in use. We have the positive testimony 

 of numerous experiments to prove that many 

 substances of liiah chemical energy are capable 

 in small quantities of favoring the growth of 

 plants. 



Without, therefore, advancing any hypothesis 

 as to the peculiar agenCy of the sulphates and 

 other matters contained in these gypseous clays, 

 or atteujpting, a priori, to pronounce upon theh 

 effects either as salutary or injurious, I feel sufti- 

 ciently sustained by observation in expressing it as 

 my opinion, that tliey will one day be made availa- 

 ble in the agriculture of this region— and I would 

 urgently sui^gest the importance of making care- 

 fulexperiiuents to determine the quantity in which 

 they may be safely and advantageously apjjlied. 

 But in all such trials, let it be borne in mind, that 

 only small quantities of such of these materials as 

 are strongly styptic and sulphureous should be 

 employed. 



The eocene strata of the peninsula are com- 

 prised in the district lying between a line connect- 

 ing Mathias's point on the Potomac, with the 

 mouth of Chingoteague creek on the Rappahan- 

 nock, and another and crooked line nearly coincid- 

 ing with the eastern boundary of the sandstone 

 fbnnation in Stafford county. These beds were 

 found to exhibit le.ss uniibrmity of arrangement 

 than those on the Pamunkey and Janjes rivers, 

 formerly described. In general, the lowest stratum 

 is of a dark sireenish blue color, and those which 

 lie above it, have various shades of yellow, green- 

 ish grey, and brown. In many instances, the 

 upper strata are devoid of shells, but replete with 

 their casts and impressions, and with the excep- 

 tion of generally containing a notable amount of 

 green sand, are strikingly analogous in composition 

 to the gypseous and sulphureous strata of the 

 meiocene. To make the resemblance still more 

 complete, a thin layer of ferruginous gravel or 

 rock frequently overlies these beds, and forms the 

 boundary between them and the meiocene. 



This remarkable resemblance in the situation 



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