GREEN SAND. 



GREEN SAND. 



artificial production of humus, and the cultiva- 

 tion of different kinds of plants upon the same 

 field in such an order of succession, that each 

 shall extract only certain components of the 

 soil, while it leaves behind or restores those 

 which a second or third species of plant may 

 require for its growth and perfect develope- 

 ment. 



"Now, although the quantity of humus in a 

 soil may be increased to a certain degree by 

 an artificial cultivation, still, in spite of this, 

 there cannot be the smallest doubt that a soil 

 must gradually lose those of its constituents 

 which are removed in the seeds, roots, and 

 leaves of the plants raised upon it. The fer- 

 tility of a soil cannot remain unimpaired, un- 

 less we replace it in all those substances of 

 which it has been thus deprived. (Org. Chem.) 



GREEN SAND. This mineral fertilizer, 

 which, in some portions of the United States, has 

 been of such immense service as a manure, and 

 especially in restoring worn-out soils to produc- 

 tiveness, is found in great abundance in certain 

 portions of the Atlantic States. The stratum 

 in which it abounds as the principal ingredient 

 commences in Monmouth county, New Jersey, 

 at the base of the Highlands of Nevesink, and 

 along the shore of the Atlantic from a little 

 north of Long Branch to Shark Inlet. Ranging 

 south westward, it passes in a wide belt through 

 Monmouth, and gradually contracting, runs 

 parallel with the Delaware river, at a distance 

 of a few miles, to Salem. It is prolonged across 

 the state of Delaware, in a narrow strip, to the 

 edge of Maryland, where it disappears under 

 the overlapping tertiary formations. The mi- 

 neral shows itself again on the Potomac and 

 through the tide-water region of Virginia, but 

 in a different stratum, in which it forms a less 

 proportion than in the so-called "green marl" 

 of New Jersey and Delaware. 



The green sand or " marl" of New Jersey, is 

 the second stratum in the ascending order of 

 the five which compose the upper secondary 

 or cretaceous group of that state. Strictly 

 speaking, says Professor H. D. Rogers, it com- 

 prises several subordinate beds, all belonging, 

 however, to two principal varieties. In the 

 first of these, the green, granular mineral is the 

 predominant and characteristic ingredient. The 

 second consists, on the other hand, of a dark- 

 blue clay, mingled with more or less silicious 

 sand. This latter material constitutes the usual 

 floor upon which the true green sand deposit 

 rests. In New Jersey, between Long Branch 

 and Deal, the marl stratum has been penetrated 

 thirty feet. The upper two feet consist of a 

 green clay, seemingly derived from the disin- 

 tegration of the green grains, intermixed with 

 a large proportion of yellowish- white clay. The 

 main marl-bed, having a thickness of about 

 twenty-six feet, contains several subordinate 

 layers; but all contain a large share of the 

 green grains. Beneath the whole there is a 

 grayish -yellow clay, in which the grains 

 abound; they are remarkably large, and are 

 associated with numerous casts of shells. 



"When," says Professor Rogers, "we behold 



a luxuriant harvest, gathered from fields in 



which the original soil is a kind least of all 



congenial to vegetation ; when we find that all 



586 



this fertility, contrasting so strikingly with the 

 barrenness around it, proceeds from a few 

 granules of a substance sparsely distributed 

 through the enormous and counteracting ex- 

 cess of sea-beach sand, more arid than the soil 

 to which it is applied, are we not led to look 

 with admiration on the potent properties of 

 this curiously constituted mineral? The de- 

 velopements of geology are full of instances 

 like this, showing in how many unlooked-for 

 ways the mineral world may be made subser- 

 vient to the good of mankind. 



" This striking proof of the fertilizing power 

 of the marl ought to encourage those districts 

 not directly within the tract, where some of the 

 strata possess the green granules in a sensible 

 proportion. It expands most materially the 

 limits of the territory where marling may be 

 attempted, and points us to many beds as fer- 

 tilizing, which otherwise would be deemed 

 wholly inefficacious. 



"There can be no doubt that the agriculture 

 of our seaboard states is destined to derive es- 

 sential benefit from the remarkably wide dis- 

 tribution of this green granular mineral under 

 various geological relationships, besides those 

 in which it presents itself in New Jersey. 



"Thus the tertiary shell-marls of Delaware, 

 Maryland, and Virginia, and, I might add, of 

 other states still farther south, contain not un- 

 frequently as high a per centage of the green 

 sand as does the sea-beach sand upon the coast 

 of Monmouth county, New Jersey ; and I may 

 mention that my brother, Professor William B. 

 Rogers, of the University of Virginia, charged 

 with the geological survey of that state, has 

 already done important service to the agricul- 

 ture of some districts, by discovering and call- 

 ing attention to the existence of the green sand 

 in the tertiary strata of Virginia." 



" Composition of the green sand. The predomi- 

 nant and often the sole ingredient in this bed, 

 is a peculiar mineral, occurring always in the 

 form of small, dark granules, about the size of 

 I grains of gunpowder. Their form is roundish, 

 and they are often composed of two or three 

 smaller ones united together; a distinctive fea- 

 ture, by which they may at once be recognised 

 from other dark kinds of sand. Though they 

 contain on the average nearly fifty per cent, of 

 silica, they are not gritty, but may be readily 

 bruised between the teeth, or upon the nail ; 

 and some varieties, when moistened, admit of 

 being kneaded into a half-plastic mass, like 

 impure clay. The prevailing colour of the 

 grains is a deep green, though sometimes the 

 tint is as light as that of verditer. It is often 

 of a dull greenish-blue, and not unfrequently 

 of a dark chocolate colour. 



"Along the eastern side of the marl tract in 

 Monmouth, Burlington, and Gloucester, the 

 stratum comprises very generally two varieties 

 of the green sand, distinct as to colour, and 

 holding generally the same relative position to 

 each other. The uppermost layer, where it 

 appears (for it is not always present), is of a 

 light and glowing green, having very nearly 

 the hue of the green paint called verditer : while 

 the lower one is the common dark variety, of 

 a dull bluish-green, or sometimes of a dull blue 

 colour from adhering clay. 



