GREEN SAND. 



GREEN SAND. 



considerable disparity in favour of the green 

 sand. Placing the home value of farm-yard 

 manure at 100 cents for each two-horse load, 

 and that of the marl at 25 cents per load, we 

 have the expense of manuring one acre $200; 

 of marling the same $5. 



"This being an experiment, an extravagantly 

 large dressing of manure was employed, but 

 not exceeding the usual average application 

 more than the 20 loads of marl surpassed what 

 was necessary. 



"Experience has already shown that land 

 once amply marled retains its fertility with 

 little diminution for at least 10 or 12 years, if 

 care be had not to crop it too severely ; while 

 with all practicable precaution the stable ma- 

 nure DHMI bo renewed at least three times in 

 that interval to maintain in the soil a corres- 

 ponding decree of vigour. 



"At the Squankum pits, which are very ex- 

 tensivr 1 , :h<' marl is sold at the rate of 37$ 

 cents the load, the purchasers having to dig it. 

 It is tran> ported by wagons to a distance, in 

 some directions, of 20 miles, and retailed, when 

 hanleii that far, at the rate of 10, or even 12$ 

 cents per bushel, being very profitably spread 

 upon the soil in the small proportion of 25 or 

 even 20 bushels to the acre." 



This is certainly a strong proof of the high 

 estimation in which green sand is held as a 

 I by the prudent and thrifty farmers of 



Nf\v Jersey. 



>sor Booth, in the report of his geolo- 

 gical survey of the state of Delaware, has 

 given much highly interesting information in 

 regard to irreen sand. In all essential particu- 

 lars, the marl-beds found in Newcastle county 

 resemble those of New Jersey described by 

 ' 



"Practically speaking," says Prof. Booth, 

 "there are two principal kinds of green sand, 

 that containing lime as an essential ingredient, 

 and that consisting chiefly of green particles. 

 The former contains variable quantities of 

 carbonate of lime, the highest limit yet ob- 

 served being twenty-five per cent. The ave- 

 rage composition of the latter, in its natural 

 state and selected, may be thus expressed: 



Silica 

 Potassa - 

 Protoxide of iron - 



lamina 

 Water - 



Unselected. 

 58 



7 

 23 



5 



100 



10* 



100 



The first is either cretaceous, containing finely 

 divided carbonate of lime not formed by com- 

 minuted shells, and occurring on the canal; or 

 decomposed calcareous, on the western limit 

 of the state, from which the calcareous matter 

 has been wholly or partially removed, although 

 abounding in casts of shells; or shelly green 

 sand, on the southern line of St. George's hun- 

 dred, in which there is no fine calcareous mat- 

 ter but that of comminuted shells. The second 

 contains mere traces of lime, and consists of 

 green sand particles, with variable quantities 

 of clay and common sand, and is either bluish- 

 green, and of the finest quality, as found on 

 Dra\>yer's and Silver Run ; or yellowish-green, 

 contain ing white silicious sand, as on Draw- 



yer's and the Appoquinimink; or black-co 

 loured, decomposed externally, rarely interna. 

 ly, and containing both white sand and argil- 

 laceous matter, from Silver Run to Scott's Run^ 

 or dark-coloured, and containing pyrites, as 

 from the south-west corner of St. George's 

 hundred, and along the ridge to the Deep-cut; 

 or, lastly, the blue micaceous sand of the Deep- 

 cut, rarely containing particles of green sand, 

 although abounding with casts and impressions 

 of shells characteristic of the green sand for- 

 mation. We have seen that the yellow sand 

 is the principal member of the series, both 

 over and underlying the green sand; that it is 

 characterized by its uniformity of grain and 

 colour, and, rising to the surface, constitutes 

 the chief and most valuable soil of the region. 

 We farther observe that the green sand stratum 

 is undulating, and varies in its depth, the ave- 

 rage thickness being 21 feet, from which we 

 may form a rough estimate of the amount con- 

 tained in the whole district. It is 7 miles long, 

 and nearly 6 broad, and therefore embraces 

 about 44 square miles. Deducting from this 

 one-quarter for the place where it fines out, 

 and for streams, ravines, &c., we have 33 

 square miles underlaid by green sand. There 

 are then 102,220,800 square yards, which mul- 

 tiplied by 7 yards, the average thickness, gives 

 715,545,600 cubic yards of green sand in Dela- 

 ware. Supposing, then, that the 1 -100th part of 

 it is accessible, we have more than 7,000,000 

 cubic yards which may be made available. In 

 a majority of cases, the flowing of water into 

 the pits presents a source of inconvenience 

 that may be remedied without great difficulty, 

 and with a trifling expense, compared with the 

 value of the material." 



Upon the subject of the fertilizing properties 

 of green sand, Professor Booth makes the fol- 

 lowing highly interesting observations: 



" When it is decomposed by the ordinary 

 processes of the laboratory, only a small quan- 

 tity of silica and all the other constituents being 

 dissolved, we may regard the oxide of iron, 

 potassa, and alumina as performing the prin- 

 cipal functions, assisted by the presence of 

 water. The useful action of potash or of ashes 

 in the soil has been long acknowledged, and 

 hence, as soon as it was known that the green 

 sand contained potassa, its utility was imme- 

 diately referred to that alkali ; latterly, how- 

 ever, the opinion has gained ground that the 

 protoxide of iron plays an important part by 

 acting with the organic matter in the soil, in a 

 manner resembling the saponification of oil by 

 potash. 



"The addition of much unleached ashes to a 

 soil determines the formation of salts of potas- 

 sa, which, being very soluble, are taken up in 

 excess by growing plants, and produce such 

 luxuriant vegetation as to cause it, technically 

 speaking, to burn up. The same operation 

 would probably occur with protoxide of iron, 

 were its salts not soon converted into more in- 

 soluble humate and crenate of the peroxide. 



"It might be objected by many that grrep 

 sand being decomposed with difficulty by me 

 powerful acids of the laboratory, there is litlte 

 probability that it can be resolved into its con- 

 stituents by the feeble action of humic or ai 



591 



