NATURAL FORMATION OF SOIL.
Nothing can be more truly beautiful in itself, or more deeply interesting to a reflecting mind, than the process by which Nature constantly produces an accession of soil, and an accumulation of vegetable matter to render it fertile. The process is varied so as to be exactly adopted to overcome the obstacles which the circumstances of each particular district present; but although the means employed are infinitely various, the final result is always the same. When the surface of a rock, for instance, becomes first exposed to the atmosphere, it is at once attacked by agents which operate mechanically and chemically. Light calls into activity the latent heat ; the pores become, by that means, sufficiently enlarged to admit particles of moisture, which gradually abrade the surface and produce inequalities ; upon these inequalities the seeds of lichens are deposited by the atmosphere ; these forerunners of vegetation take root, and the fibres by which some sorts of these diminutive plants adhere to the rock, concoct a vegetable acid peculiarly adapted to corrode the substance with which it comes in contact, and increase the inequalities which heat and moisture had already formed. These diminutive plants decay and perish : when de- composed, they form a vegetable bed suited to the production of larger plants ; or when the surface of the rock happens to present clefts, or natural crevices, they fall into them ; and there mingling with fine particles of sand, conveyed thither by the atmosphere, or crumbled by the action of the air from the internal surfaces of the crevices themselves, they form fertile mould. Nature, having advanced thus far in her preparations, makes another for- ward step. She sows the soil which has been created by the decomposition of vegetable matter, with some of the more perfect plants, which it has now become capable of sustaining. These continue to be produced and decom- posed until a soil has been prepared of sufficient depth and richness to bear plants of still higher quality and larger dimensions. The process of Nature acquires accelerated force as it advances towards its consummation. When a sufficient depth of soil has been formed to produce ferns, for instance, these annually decay and die : their decomposed materials gradually form little conical heaps of vegetable mould round the spot on which each plant grew. When this has gone on for a period of sufficient length to spread these cones
over a given surface, Nature takes another stride : she sows furze, thorns, and briars, which thrive luxuriantly, and by annually shedding their leaves, con- tribute, in the end, to add greatly to both the depth and fertility of the mould. This species constitutes, in truth, the means which Nature principally uses in preparing a bed for the growth of the more valuable trees. It is well known that these are the plants which make their first appearance in fallows, or in woods which have been recently cut down. Into the centre of a tuft of brambles is accidentally carried the seed of the majestic oak. Meeting with a congenial soil, it soon vegetates : it is carefully and effectually cherished and protected by its prickly defence, against all injuries from the bite of the animals which roam over the waste. The larger trees having reached a height and size which render shelter unnecessary, destroy their early nurses and protectors' by robbing them of their light and air indispen- sable for their well-being. The thorny plants then retire to the outskirts of the forest; where, in the enjoyment of an abundant supply of light and sun, they continue gradually to extend the empire of their superiors, and make encroachments upon the plain, until the whole district becomes at length covered with magnificent trees. The roots of the larger trees penetrate the soil in all directions : they even find their way into the crevices of the rocks, filled as these are already, by decomposed vegetable matter : here they swell and contract, as the heat and moisture increase or diminish. They act like true h•vers, until they gradually pulverize the earthy materials whichthey haveheen able to penetrate. While the roots are thus busy underground, boring, under- mining, cleaving, and crumbling everything that impedes their progress, the branches and leaves are equally indefatigable overhead. They arrest the volatile particles of vegetable food which float in the atmosphere. Thus fed and sus- tained, each tree not only increases annually in size, but produces and deposits acrop of fruit and leaves. The fruit becomes the food of animals, or is carried into a spot where it can produce a new plant : the leaves fall around the tree, where they become gradually decomposed' audio the lapse of ages, make a vast addition to the depth of the vegetable world ; and whilst the decomposition of vegetables makes a gradual additiont o the depth of the cultivable soil, another cause equally constant in operation contributes to increase its fertility : the produce of the minutest plants serves to subsist myriads of insects ; after a brief existence these perish and decay ; the decomposed particles greatly fer- tilize the vegetable matter with which they happen to mingle. The period at length arrives when the timber, having reached its highest measure of growth and perfection, may he cut down, in order that the husbandman may enter upon the inheritance prepared for him by the hand of the all-wise and zdl-benefieent Author of his existence. Such is the system which they that have eyes to see may see. Plants which appear worthless in themselves- those lichens, mosses, heaths, ferns, furze, briars, and brooms, in which economists, forsooth, perceive only the symbols of eternal barrenness-are so many instruments employed by Perfect Wisdom in fertilizing new districts for the occupation of future generations of mankind.-Quorterty Review ; article, "Cultivation of l'fiaste Lands."
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