CHAPTER II.

MINERAL GEOLOGY, as it is properly characterised by Cuvier1, or, according to a more recent denomination, GEOGNOSY, is no other than mineralogy, or the science of minerals, attempting to determine, by the indications of mineral phenomena alone, the two historical facts; viz. the MODE of the formation of the primitive mineral substances composing this earth, and the MODE of the changes which those primitive substances have subsequently undergone.

That this is a true definition or description of this geology, is attested, both by the statements of its teachers, and by their reports of the history of its origin.

66

Geognosy, said Werner, is that part of Mineralogy which brings us acquainted, in a me"thodical order, with the terrestrial globe in ge"neral; but especially, which brings us acquainted, in a particular manner, with the positions of the minerals which compose it: "it reveals their relations, the nature of their

1 "La Géologie Minérale." Ossemens Fossiles, Disc. Prél. p. 26.Theory of the Earth, sect. 22. This latter treatise revised, forms the Preliminary Discourse of the former great work, of which a new edition was published in 1823. To that new edition the references are made in this present work.

disposition, as well as that of the minerals them"selves; and FINALLY, it is able to conduct us to NOTIONS respecting their FORMATION1."

66

In this definition, the first three points relate to simple mineralogy, topographical and tabular; the last, which respects the historical question, characterises the Mineral Geology.

"The principal object which geognosy has in "view, (says the able disciple of Werner from "whom I have just quoted,) is,

"1. The knowledge of the mineral masses, "or rather of the different groups or systems of "mineral masses, whose assemblage composes "the solid portion of this terrestrial globe. It "considers the mineralogical composition, struc"ture and extent of each of these systems. It "treats of their reciprocal dispositions, of the cir"cumstances of their superposition one to the other, "and of the different relations subsisting between "them:

"2. Of every thing which relates to THE MODE of their FORMATION; and,

:

1" Quoique la définition que Werner donne de la géognosie, en Al"lemand, ne soit guère susceptible d'une exacte traduction française, "j'en hazarderai cependant la traduction presque littérale en disant :'La géognosie est la partie de la minéralogie qui nous fait connaître, dans un ordre méthodique, le globe terrestre en général; et surtout ' qui nous fait connaître, d'une manière particulière, les gîtes des mi'néraux qui le composent; elle expose leurs rapports, leur manière 'd'être, ainsi que celle des minéraux qui les constituent; et FINALEMENT elle peut nous conduire à des NOTIONS sur leur FORMATION."D'AUBUISSON, tom. i. p. 374. (Définition de la Géognosie par Werner.) 2 D'AUBUISSON, tom. i. p. 1.

"3. to THE CHANGES which they have undergone."

In this exposition, also, the first article describes simple mineralogy; the two latter articles, describe the same science converting itself into Mineral Geology.

If we consult the historical accounts of the origin and progress of this science, we shall find that they exactly answer to the preceding description. They relate, that the experience which had been acquired in a long course of mineralogical practice, the numerous observations which had been successively made by a series of able and acute mineralogists, and the light diffused over mineralogy, by the improvement and reformation of chemistry, engendered an ambition in succeeding mineralogists to advance beyond the mere investigation of the actual properties and positions of minerals, their description and classification; and to endeavour to detect, by means of physical principles, the mode by which they were first formed, and by which they were afterwards altered in their circumstances. And, it is this new and extraneous exercise of mineralogy, that properly constitutes the new science which is called Mineral Geology, and which assumes such exalted functions at the present day.

Thus, both the description of this geology and its history, as delivered by its most distinguished and zealous conductors, confirm the position; that

it is no other than simple mineralogy, or the science of minerals, attempting to determine, by phenomena alone, two remote and extensively important facts, pertaining to the HISTORY of this globe.

or,

66

The first thought which a consideration of these pretensions awakens in a reflecting and reasoning mind, is this question:-Can mineralogy be competent to determine, by means of physical principles alone, exclusively of all historical aid or guidance, the matter of fact in those points? Can it be competent, to "conduct us to certain "notions" respecting the mode of the formation of the primitive mineral substances of this globe? to decipher the historical monuments of its revolutions?" or, to "compel the primeval moun"tains to unfold the secrets of their origin?" or, to "trace and ascertain the causes of the changes "which have taken place in them?" For, the proper sphere of mineralogy is confined to the characters and qualities, that is, to the actual sensible phenomena of mineral matter; and, can actual sensible phenomena alone supply the means of determining, with the evidence which sound philosophy and sound reason demand, the certainty of the two past facts in question?

To this doubt, the mineral geology thus replies that it is competent to determine these two points of fact, and, with all the evidence which reason and philosophy demand; that "the happy "revolution effected by BACON and NEWTON in the

"studies of the natural sciences, was not experienced "in the science of geology until very late1;" but that, by employing the method of induction from "observation and sound principles of physics, by the

rules of an exact logic," introduced by that happy revolution; and, by adhering to the rules taught, and practised, by those great teachers; it is able to reason, securely and conclusively, from the sensible phenomena of mineral matter, to the MODE of its first formation and of its subsequent changes and that man, who has weighed the

-66

66

planets, and measured their distances, may presume to trace the operations by which the surface "of the globe was arranged".

This, then, is the test, by which the mineral geology desires that its own validity should be tried. Let us, therefore, apply our close attention, whilst it professes to instruct us upon those two heads by the rules of an exact logic, and on sound principles of physics; and let us first hear it upon the first head, which constitutes the BASIS of all geology, viz. the MODE of the formation of the PRIMITIVE mineral masses of the earth, comparing

1

"L'heureuse révolution, que BACON et NEWTON avaient opérée dans "l'étude des sciences naturelles, ne se fit ressentir que bien tard dans "celle de la géologie."-D'AUBUISSON, Disc. Prel. p. 3.

"""L'observation, les principes d'une saine physique, et les règles "d'une exacte logique." —Ib. p. 36.

3. Comparative View of the Huttonian and Neptunian Systems of Geology, p. 2, 3.