Theory of the Earth, With Proofs and Illustrations, Volume 1 (of 4)

by James Hutton

I am not avoiding to meet that question with regard to the providing of materials for such a mineral fire as may be required; no question I desire more to be asked to resolve; but it must not be in the manner that our author has put that question. He has included this supposed difficulty among a string of other arguments by which he would refute my theory with regard to the igneous origin of stony substances, as if I had made that fire a necessary condition or a principle in forming my theory of consolidation. Now, it is precisely the reverse; and this is what I beg that mineral philosophers will particularly attend to, and not give themselves so much unnecessary trouble, and me so disagreeable a talk. I have proved that those stony substances have been in the fluid state of fusion; and from this, I have inferred the former existence of an internal heat, a subterraneous fire, or a certain cause of fusion by whatever name it shall be called, and by whatever means it shall have been procured. The nature of that operation by which strata had been consolidated, like that by which they had been composed, must, according to my philosophy, be decided by ocular demonstration; from examining the internal evidence which is to be found in those bodies as we see them in the earth; because the consolidating operation is not performed in our sight, no more than their stratification which our author has also denied to have been made, as I have said, by the deposits of materials at the bottom of the sea. Now, with regard to the means of procuring subterraneous fire, if the consolidating operation shall be thus decided to have been that of fusion, as I think I have fully shown, and for which I have as many witnesses, perhaps as there are mineral bodies, then our author's question, (how I am to procure a fire) in the way that he has put it, as an argument against the fusion, would be at least useless; for, though I should here confess my ignorance with regard to the means of procuring fire, the evidence of the melting operation, or former fluidity of those mineral bodies, would not be thereby in the least diminished. If again no such evidence for the fusion of those bodies shall appear, and it be concluded that they had been consolidated by the action of water alone, as our author seems inclined to maintain, he would have no occasion to start difficulties about the procuring of fire, in order to refute a theory which then would fall of itself as having no foundation.

But in order to see this author's notion of the theory which he is here examining, it may be proper to give a specimen of his reasoning upon this subject of heat. He says, "That my supposition of heat necessary for consolidating strata is gratuitous, not only because it is unnecessary, as we have already shown, but also because it is inconsistent with our author's own theory." Let us now consider those two propositions. First, it is unnecessary, as we have already shown;— I have already taken particular notice of what we have been shown on this occasion, viz. That the earth at a certain depth may have been originally in a solid state; and, that, where it is to be consolidated, this is done by the mutual attraction of the stony particles. Here is all that we have been shown to make subterraneous heat, for the consolidation of strata, unnecessary; and now I humbly submit, if this is sufficient evidence, that mineral heat is a gratuitous supposition.

Secondly, "it is inconsistent with our author's own theory." Here I would beg the readers attention to the reasoning employed on this occasion. He says, "according to him these strata, which were consolidated by heat, were composed of materials gradually worn from a preceding continent, casually and successively deposited in the sea; Where then will he find, and how will he suppose, to have been formed those enormous masses of sulphur, coal, or bitumen, necessary to produce that immense heat necessary for the fusion of those vast mountains of stone now existing? All the coal, sulphur, and bitumen, now known, does not form the 100,000 part of the materials deposited within one quarter of a mile under the surface of the earth; if, therefore, they were, as his hypothesis demands, carried off and mixed with the other materials, and not formed in vast and separate collections, they could never occasion, by their combustion, a heat capable of producing the smallest effect, much less those gigantic effects which he requires."

Here is a comparative estimate formed between two things which have not any necessary relation; these are, the quantity of combustible materials found in the earth, on the one hand, and the quantity which is supposed necessary for hardening and consolidating strata, on the other. If this earth has been consolidated by the burning of combustible materials, there must have been a superfluity, so far as there is a certain quantity of these actually found unconsumed in the strata of the earth. Our author's conclusion is the very opposite; let us then see how he is to form his argument, by which he proves that the supposition of subterraneous heat for hardening bodies is gratuitous and unnecessary, as being inconsistent with my theory.

According to my theory, the strata of this earth are composed of the materials which came from a former earth; particularly these combustible strata that contain plants which must have grown upon the land. Let us then suppose the subterraneous fire supplied with its combustible materials from this source, the vegetable bodies growing upon the surface of the land. Here is a source provided for the supplying of mineral fire, a source which is inexhaustible or unlimited, unless we are to circumscribe it with regard to time, and the necessary ingredients; such as the matter of light, carbonic matter, and the hydrogenous principle. But it is not upon any deficiency of this kind that our author founds his estimate; it is upon the superfluity of combustible materials which is actually found in this earth, after it had been properly consolidated and raised above the surface of the sea. This is a method of reasoning calculated to convince only those who do not understand it; it is as if we should conclude that a person had died of want, because he had left provision behind him. Our author certainly means to employ nothing but the combustible minerals of the present earth, in feeding the subterraneous fire which is to concoct a future earth; in that case, I will allow that his provision is deficient; but this is not my theory.

I am not here to enter into any argument concerning subterraneous fire; the reader will find, in the foregoing theory, my reasons for concluding, That subterraneous fire had existed previous to, and ever since, the formation of this earth,—that it exists in all its vigour at this day,—that there is, in the constitution of this earth, a superfluity of subterranean heat,—and that there is wisely provided a proper remedy against any destructive effect to the system, that might arise from that superabundant provision of this necessary agent. Had our author attended to the ocular proof that we have of the actual existence of subterraneous fire, and to the physical demonstrations which I have given of the effects of heat in melting mineral bodies, he must have seen that those arguments of his, with regard to the difficulty or impossibility of procuring that fire, can only show the error of his reasoning. I am far from supposing that my theory may be free from inconsistency or error; I am only maintaining that, in all his confident assertions, this author has not hitherto pointed any of these out.

So far I have answered our author's objections as to consolidation, and I have given a specimen of his reasoning upon that subject; but with regard to my Theory of the Earth, although simple fluidity, without heat, would have answered the purpose of consolidating strata that had been formed at the bottom of the sea, it was necessary to provide a power for raising those consolidated strata from that low place to the summits of the continents; now, in supposing heat to be the cause of that fluidity which had been employed in the consolidation of those submarine masses, we find a power capable of erecting continents, and the only power, so far as I see, which natural philosophy can employ for that purpose. Thus I was led, from the consolidation of strata, to understand the nature of the elevating power, and, from the nature of that power, again to understand the cause of fluidity by which the rocks and stones of this earth had been consolidated.

Having thus, without employing the evidence of any fire or burning, been necessarily led to conclude an extreme degree of heat exerted in the mineral regions, I next inquire how far there are any appearances from whence we might conclude whether that active subterraneous power still subsists, and what may be the nature of that power. When first I conceived my theory, naturalists were far from suspecting that basaltic rocks were of volcanic origin; I could not then have employed an argument from these rocks as I may do now, for proving that the fires, which we see almost daily issuing with such force from volcanos, are a continuation of that active cause which has so evidently been exerted in all times, and in all places, so far as have been examined of this earth.

With regard to the degree of heat in that subterraneous fire, our author, after proving that combustible materials would not burn in the mineral regions, then says, that suppose they were to burn, this would be "incapable of forming a heat even equal to that of our common furnaces, as Mr Dolomieu has clearly shown to be the case with respect to volcanic heat." The place to which he alludes, I believe to be that which I have quoted from the Journal de Physique (Part I. page 139) to which I here beg leave to refer the reader. After what I have already said, this subject will appear to be of little concern to me; but, it must be considered, that my object, in these answers, is not so much to justify the theory which I have given, as it is to remove that prejudice which, to those who are not master of chemical and mineral subjects, will naturally arise from the opinion or authority of a scientific man, and a chemist; therefore, I think it my business to show how much he has misconceived the matter which he treats of, and how much he misunderstands the subject of my theory.

Mr Dolomieu alleges that the volcanic fire operates in the melting of bodies, not by the intensity of its heat, which is the means employed by us in our operations, but in the long continuance of its action. But in that proposition, this philosopher is merely giving us his opinion; and, this opinion our author mistakes, I suppose, for the fact on which that opinion had been (perhaps reasonably) founded. The reader will see, in the place quoted, or in the avant-propos to his Mémoire sur les Iles Ponces, the fact to be this; That the Chevalier Dolomieu finds those bodies which we either cannot melt in our fires, or which we cannot melt without changing them by calcination and vitrification, he finds, I say, these substances had actually been melted with his lavas; he also finds those substances, which are necessarily dissipated in our fires, to have been retained in those melted mineral substances. Had our author quoted the text, instead of giving us his own interpretation, he could not have offered a stronger confirmation of my theory; which certainly is not concerned with the particular intensity of volcanic fire, and far less with what may be the opinion of any naturalist with regard to that intensity, but only with the efficacy of that volcanic heat for the melting of mineral substances. Now this efficacy of volcanic fire, so far as we are to found upon the authority given on this occasion, is clearly confirmed by the observations of a most intelligent mineralist, and one who is actually a patron of the opposite theory to that which I have given. This being the state of the case, Must I not conclude, that our author has misunderstood the subject, and that he has been led to give a mutilated opinion of Mr Dolomieu, in order to refute my theory, when either the entire opinion, or the facts on which the opinion had been founded, would have confirmed it?