Nothing is more evident, than that the general effect of mineral operations is to consolidate that which had been in an incoherent state when formed at the bottom of the sea, and thus to produce those rocks and indurated bodies which constitute the basis of our vegetable soil; but, that indurating or consolidating operation is not the immediate object of our observation; and, to see the evidence of that operation, or the nature of that cause, requires a long chain of reasoning from the most extensive physical principles.  Our present subject of investigation requires no such abstract distant media, by which the effect is to be connected with its cause; the actual operation in general is the object of our immediate observation; and here we have only to reason from less to more, and not to homologate things which may, to men of narrow principles, appear to be of different kinds.  But even here we find difficulty in persuading those who have taken unjust views of things; for, those who will not deny the truth of every step in this chain of reasoning, will deny the end to which it leads, merely because they are not disposed to admit the progress of that order which appears in nature.

In the last chapter, I have been using arguments to prove that M. de Luc has reasoned erroneously, in concluding the future stability of a continent; and I have been endeavouring to show that our continent is necessarily wasted in procuring food to plants, or in serving the various purposes of a system of living animals.  We have now in view to illustrate this theory of the degradation of the surface of the earth; a theory necessarily leading to that system of the world in which a provision is made for future continents; and a theory explaining various natural appearances which otherwise are not to be understood.  A door may thus be opened for the investigation of natural history, particularly that which traces back, from the present state of things, those operations of nature which are more immediately connected with what we take much pleasure to behold, viz. the surface of the earth stored with such a variety of beautiful plants, and inhabited by such a diversity of animals, all subservient to the use of man.

There are two ways in which we may look for the transactions of time past, in the present state of things, upon the surface of this earth, and read the operations of an ancient date in those which are daily transacted under our eye.  The one of these is to examine the soil, and to trace the origin of that which we find loose upon the surface of the earth, or only compacted by the soft and cohesive nature of some of its materials.  In thus studying the soil we shall learn the destruction of the solid parts; and though, by this means, we cannot form an estimate of the quantity of this destruction which had been made, we shall, upon many occasions, see a certain minimum of this quantity which may perhaps astonish us.