CHAPTER VII. ON THE APPLICATION OF GEOLOGY TO THE QUALITY OF LAND. FRUITFUL and sterile land, taken in a comparative sense, has been originally determined by the laws of Geological deposition. The results are apparent in every stage of the earth's progress towards existing appearances. Dense and sluggish particles of matter, which are probably laminated or flattened in their atomic bases, and cease to roll about so readily, from that cause alone, as those which preserve a more spherical and divisible form, are necessarily the first deposited by the operating principles of universal fluidity, and brought to a state of natural rest. These may be denominated the least active atoms of matter, merely owing to their being bruised or flattened. Driven into little masses from this cause, they consequently lose that fluid activity which contributes to keep them in motion. Spherical atoms, owing to a difference in form, necessarily remain more finely divided and active, and have a less tendency to take a state of repose than such as are flat, dense, and sluggish. To speak somewhat figuratively, they are more idle and unfitted for the purposes of organic action, and working smoothly in regulated forms. An atomic theory so familiar may be aptly illustrated by the travelling beach on the English borders of the Solway Frith. The tidal current in flowing up the estuary has driven a bed of rough shingle before it, that underwent deposition within the boundaries of the channel. Sand being more rounded and finely divided, having a less tendency to rest upon an accumulating beach, was naturally driven around its extreme point, and finally deposited in more still water. Finely divided clay, also, being more active than sand, was by a similar law propelled more forwards, and deposited on a base of sand. Vegetable and animal remains, which contribute so much to the fruitfulness of land, had a still less tendency to deposition, and finally took rest on the surface of the whole. The fertility of the soil in the Low Holm, though of a common origin, differs from such causes materially in quality. The ordinary laws of fluidity and deposition having mainly contributed to assort the various particles of matter, of which the soil is composed, and different degrees of original fertility prevail, accordingly as their density and lightness have determined the order of deposition. We so far observe a material cause why soils of a like origin, may at the same time differ materially in the constituent proportions of matter, and in natural fertility also. In one the proportional composition of sand may be in excess, in another fine clay, and a third may be too much composed of vegetable remains. Again, as finely divided lime is scarcely a component element in these marine formations, we ascertain a defect which might have been corrected. Notwithstanding these differences in the quality of land in the Low Holm, a kindred resemblance obtains which may be readily traced to a common geological origin. Of course, this class of land occupies a low level. Seldom so much as ten feet above high spring tides, often within their level, and even where the best land is situated, defended by embank ments. A defect in the land of these plains arises from the low level on which they lie. An even surface contributes to the retention of water, on the supersoil in the first place, and next in the subsoil. The elements of chilling dews and fog are, therefore, generated, that either occasion diseases in plants, or exercise a withering influence, and lead to blights. The climate also being damp, crops are liable to sustain injury from excesses in temperature; cold more especially. Effective draining, which purposes to draw off an excess of dampness from the soil, points out an efficacious remedy for natural imperfections; contributing to remove the baneful influence of stagnant water from the surface, it gives land the firmness required for bearing cattle in wet seasons, and corrects those chil ling dews so apt to occasion mildew in wheat, and other diseases in grain crops to which soils on so low a level are liable. The next class of deposits met with on the plain of Carlisle, or western Cumberland, is composed of diluvial clays and sand, ascending from ten feet above the level of the sea to an elevation of one hundred feet. We here again notice a common Geological origin in which a considerable difference in the quality of land is detected. Nor does this difference rest here. The application of art has brought about changes for which nature has prepared the way. Not more than three centuries ago, mills have been erected, at intervals, for grinding corn, upon streams which descend from high levels, and through intermediate vallies. Whilst a state of nature decided the deposits of those vallies, and where descents were found which afforded adequate mill streams, the repeated ravages of land floods appear to have covered most of the adjacent land with gravel and sand to a considerable depth, and upon its surface. There are to this day full evidences remaining that when the requisite bays had been constructed for acquiring mill streams, and land floods were checked by such means in their descent upon the low lands, the intermediate spaces of smooth water so produced, promoted an accumulation of sloughy earth, and covered these vales from three to five feet in thickness with a fresh order of depositions. Art still more modern, has applied under-ground draining to these vallies, and land highly fertile in quality has been by such means obtained. Another class of these vales, the seat of land springs, less subject to alluvial depositions, producing aquatic plants and brushwood commonly found in swamps and bogs, gradually acquired a soil composed of vegetable remains, commingled with sediment washed from off cultivated lands and the off-scourings of villages, until an accumulated super-soil has been formed from one to three feet in thickness. Art has now discovered and applied the draining tile to the complete drainage of such swamps, and resorted to irrigation as an effective means of decomposing a mass of vegetable earth, which contains a store of the elements of fertility, besides a deposition of rich alluvian is at the same time spread over the surface. Fruitful meadows have therefore arisen from beneath living waters, which bear along with them seeds of fertility; and fresh and blooming vales have appeared, where the swamp and the wilderness had previously disfigured a flowing landscape. Nature and art combined, twin sisters in the hands of man, in all the profusion of illimitable products and prodigality of organic being, have smiled upon his busy toils. The bounties of Providence have been disclosed to view, and vast means of subsistence yet in store, prepared for our use by omniscient intelligence, are now elicited in the most available forms; and |