« PreviousContinue »
MINERAL AND MOSAICAL
The characters which unfold themselves to PART I. our view, in examining the substances of this
CHAP. I. globe, point out to us some period, or periods, in which the order of its structure sustained violent agitation and alteration. part of the earth we encounter unequivocal evidence of disruption, subsidence, and subversion of its hardest and most solid materials; and we discover remains, equally unequivocal, of organic matter, both animal and vegetable, involved and deeply imbedded in other of its materials, which are soft, or which must have been so at the time when those foreign substances were imbedded within them. Monuments, so wonderful and so important, have
PART I. naturally stimulated the curiosity of man to
inquire, and to endeavour to ascertain, how and CHAP. I.
when those amazing effects were wrought in the substance of our globe.
An extended investigation of the same characters has led to a further observation : that those foreign organic substances are not found indiscriminately in all the materials of which our earth consists; that they are found only in one order of them, while in another order they are never found at all. This remarkable fact, well established, has given occasion to a division of the materials of the earth into two general classes, distinguished chiefly by the presence and the absence of organic fragments; and, since it has been observed, that the materials in which those fragments occur, bear, in general, the appearance of sediment deposited in water; whereas, those in which they never occur wear a crystalline appearance;
their respective formations have been reasonably ascribed to different immediate causes. And because those which appear to be sedimentary are observed to be deposited upon those which appear to be crystalline, the latter, which sustain the former, are with equal reason assumed to be of a more ancient date: and from hence all the mineral matter of this globe has been distributed scientifically into two principal
divisions, entitled primary and secondary; the PART I. first of which comprises the crystalline matter, containing no organic fragments, of which kind are granite rocks; and the second comprehends the sedimentary matter, in which alone those fragments are contained — such are, calcareous or argillaceous earths containing sea-shells.
An intermediate or transition class has of late years been introduced, with much accuracy, between the two; comprising mineral masses formed of the conglutinated fragments of different primary rocks, but rarely enclosing any organic fragments—such is that species of rocks which is called pudding-stone.
In this general distribution of terrestrial matter, the primary class, exhibits to us the mineral matter of the globe in its primitive formation and texture, previous to the existence of organized beings: the intermediate class, exhibits the same matter in a state of extensive fracture and disorder, in consequence of some violent force exercised upon it; and the secondary class, indicates the universal subjection of mineral matter to the dissolvent quality and mechanical action of water, subsequently to the existence of organized beings. From which general diversities, the intelligence is naturally led to apprehend corresponding and succeeding periods in the remoteness of time. '1. The
PART I. period, of the beginning of this terrestrial sys
tem, when it received its first mineral formation. 2. The period, of a violent disruption and dispersion of part of the mineral substances composing that first formation ; and, 3. A period, of the general destruction of animal and vegetable life; and of the occupation of our present earth by the waters of the sea. These several characters, unequivocally marked, and of late years observed with peculiar ardour and application, have excited the ambition of science to investigate, and to endeavour to detect, the mode by which, and the times in which, those several classes of matter received their respective sensible formations.
The particular science which undertakes to lay open to us these profound historical secrets of time and nature, has received the denomination of Geology; a science, whose pretensions are of the most exalted and comprehensive kind; since it extends its view to the commencement of time, and embraces within its scope the origin and revolutions of all terrestrial matter, mineral, vegetable, and animal. To attain to the certainty of fact, in these important particulars, is to arrive at an universal principle of truth, diffusing light and distinctness over every object of human contemplation; to be seduced into error respecting them, is to be