"The great branches of the Comparative Geology and Comparative Palæontology, (or study of Fossil Remains,) of distant countries, much as they have recently advanced, have as yet even a still wider interval to pass over than that which they may have already accomplished before they shall have obtained that degree of completeness which alone can qualify them to serve as sound bases in any geological theory."-CONYBEARE-Geological Report of British Association. "While so large a portion of the globe is geologically unexplored-while all the general views which are to extend our classifications satisfactorily from one hemisphere to another, are still unformed-while the organic fossils of the tropics are almost unknown, and their general relation to the existing state of things has not even been conjectured,-how can we expect to speculate rightly and securely respecting the history of the whole of our globe? and if geological classification and description are thus imperfect, the knowledge of geological causes is still more so."WHEWELL'S History of the Inductive Sciences, vol. iii. p. 621. SECTION I. GENERAL VIEW OF THE EARTH'S STRATA, AND THEIR AGGREGATE THICKNESS. THE creation of the world, and the planetary system of which it forms a part, is an exercise of the Divine power so utterly beyond the conception of man, that, in speculating upon it, he is glad to throw around the whole the envelopment of infinitude, and filling his imagination with ideas of boundless space and indefinite duration, he endeavours to bring up his mind in some degree commensurate with the subject. It is in this way, perhaps, as well as from that innate love of novelty implanted in the breast, that the prevailing opinions of the present time seem to tend so much to the idea of an extreme antiquity of the globe beyond that definite period within which tradition and common belief has hitherto confined it. Yet if it be pleasing for the mind to forego the trammels of authority, and, starting with a few striking phenomena, to track creation through a revolving series of worlds till it is lost in the vague and indistinct boundaries of time; it is a no less singular, and perhaps as sublime, speculation, to think that this earthly scene of things, involving so much that is vast and important both in the moral and physical world, and occupying but a brief moment and a mere point of space in the great theatre of eternity, should yet have these points and limits accurately defined and indicated to the mental intelligences, for whose aid and use they are declared to have been created. The very nature of the study, too, is such as to have a continual tendency to carry the mind beyond the sober boundaries of facts into the airy regions of hypothesis. For, laying aside the speculations of the cosmogonists, who have formed worlds out of red hot masses severed from the sun, or from fluid spheres of saturated water, or condensed nebulæ, which had hitherto floated as shapeless flocculi in space, there is in the study of the visible phenomena of the earth's strata, sufficient of wonderful interest to excite and warm the imagination. The remains of unknown plants and animals, which have been entombed for ages in the hard rocks, and which present themselves only in fragments and disjointed members, yet sufficiently distinct to indicate many kinds of being which no longer have an existence on the earth the exhumation of skeletons of unknown monsters, and the impressions |