DISCOVERIES OF THE MODERN GEOLOGISTS. THE Geological Society of London, One of the chief disputes of modern geologists was based upon the question of whether the formation of the solid parts of the earth and its earlier changes were brought about by the agency of water or fire. At the head of the first school was Werner, and of the second Hutton; and their followers were therefore denominated either Neptunists or Plutonists. The globe, as it is customary to call the earth, is held to be, in shape, an oblate spheroid body, flattened at the poles; and it is presumed to have constantly revolved upon its axis. The primitive state of the earth was probably fluid, and its surface became gradually solidified by the slow evaporation of its heat, or other natural causes. We may conceive this fluid mass revolving round the sun with other planets in the immensity of space, and carrying with it an atmosphere supposed to extend between forty and fifty miles above its surface. The process of cooling would condense a portion of this atmosphere into water, which therefore occupied some of the earth's surface in consequence. In this state of things it is quite clear that the present races of living beings could not exist, and that the earth was then unfitted for organisation. Therefore the earliest crystallisations would contain no organic remains; and such is the factno vestiges of life are found in the primitive rocks. But as the earth continued to cool, the waters, which more or less covered it, settled into a smaller space, and thus left islands in the midst of the ocean, and found their way into crevices and abysses. The subsiding water must have left deposits behind it; and thus we have earth, air, and water, created from a uniform fluid mass by the operation of gravity and attraction; and a state fitted for living beings was engendered, which accordingly produced examples of the simplest organisation. The earliest living forms, therefore, whose exuviæ appear in the second order of strata, are shellfish, and the coral animals or zoophytes, probably preceded by aquatic vegetables growing among the submarine rocks. This early period of life must have been attended with the work of myriads of zoophytes, whose industrious labours produced such extensive reefs of calcareous rocks along the shores of the ocean, whilst the prolific shell-fish embedded the earth with shells to that immense amount which we now see in the secondary rocks. The fecundity and activity of this incipient animate world were the sources of much structure and fertilisation; and, the temperature of the earth being still high, such plants as were fitted for heat appear to have been created in abundance. The impressions of these exactly resemble plants now flourishing in the tropics. The busy zoophytes, in the mean time, were actively employed in throwing up from the depths of the sea new formations; and various molluscæ, and ordinary fishes perhaps, found nourishment from the submarine vegetables. The first order of secondary rocks originated evidently in copious deposits from the cooling liquid holding many materials in solution, and amalgamated with sand, immense masses of coral rocks, the exuviæ of shell and other fish along the shores of the primitive lands. Then, the temperature of the earth still cooling, whilst such deposits and unions were going on, some of the species of oviparous reptiles were created; and in the bays and creeks of the primitive land-formations sported the turtle and the crocodile, and the gigantic sauri, whose remains adorn our geological museums. Still, the order of things must have widely differed from that now prevailing; the earth's crust must have been very slender, and the sources of its fire very near the surface. Contractions in different parts of the cooling mass caused crevices to form, and the waters rushed into them, whereby sudden condensations ensued, which created volcanic eruptions, uplifting one portion of the surface and depressing another. Thus mountains first arose, and new and extensive depositions were made from the primitive ocean-changes evidently very frequent in the early epochs of nature. The only monuments of the living creation of these periods are the coarser kinds of plants, fishes, birds, and oviparous reptiles, beings capable of resisting the war of the elements then in operation. But as these subsided, and the cooling of the earth advanced, the mountain-chain preserving the necessary inequalities of the earth's temperature, more perfect beings were brought into existence; and then came forth the original antediluvian elephant, the mammoth, the megalonis, the megathurium, and a gigantic hyæna, all now known to us only by the fossilated remains of their skeletons. At this period, probably, the temperature of the ocean was not much higher than at present; for the changes produced by occasional eruptions of it have left no consolidated rocks, such as were formed at earlier epochs, notwithstanding one of these eruptions appears to have been very extensive, not only from the tradition handed down to us in the Mosaic history, but from examinations of the earth, and other circumstances. This seems to be the only great catastrophe of which we have any written account. revolution was not only very general, but evidently of long duration, as appears from the immense collections of water-worn stones, gravel, and sand, VOL. V. NO. XXIX, This usually called diluvial remains. It is also probable that this effect gave rise to the origin of a new world in the southern hemisphere, by the agency of volcanic fire. The state of the globe becoming more and more consolidated, and permanently fitted for living beings of superior organisation, and those tremendous convulsions depending upon the destruction of the equilibrium between the heating and cooling agencies in action, subsiding, the quietude of the earth presented a favourable opportunity for the creation of a higher species of the mammiferæ than hitherto produced, and accordingly man was created. Since this remarkable epoch no great and sudden revolution has occurred, although the surface of the earth is constantly undergoing slow and often imperceptible changes, from the perpetual operation of causes which have never altogether ceased since the first formation of the globe. Our destinies suffer no alteration from the changes now going on; our species is greatly extended, and it maintains its position undisturbed as lord of the creation in every latitude. Volcanic fires occasionally give rise to new islands raised from the bed of the ocean, and portions of the old continents are constantly being washed away by rivers and mountain-torrents. But such changes are too powerless in the grand system of the earth to produce any great effects in the moral or physical departments of the creation. The present existing crust of the earth is comparatively thin, and the surface of our globe surrounds a fluid nucleus of ignited matter, from which circumstances we appear to be by no means secure from a general catastrophe by fire. The temperature of the interior of the globe is higher than at the surface, as we find by experiments in mines; for the deeper we penetrate, the greater is the heat. The great number of hot springs found in almost every country, arising from excessive depths, tends to favour this idea. This want of equilibrium in the temperature of the earth is probably the cause of volcanoes; so that the open craters of burning mountains act as the safety-valves of the earth, by which the terrific effects of suppressed gaseous expansion are modified and restrained. Volcanoes have been accounted for upon the principle of partial chemical changes, such as arise from the action PP of the air and water upon the combus- The lias, limestone, and other strata of the earlier formations, contain remains of beings which evidently belonged to an order of events entirely different from the present order. There are to be seen the embedded forms of gigantic plants, resembling more the palm-trees of equinoctial climates than If we suppose the That the whole surface of the globe has undergone a great change since its early formations commenced, sometimes by violent convulsions, and gradually by slowly operating causes and more insignificant catastrophes, is proved by all geological investigations. The destruction of a former order of things, and the existence of a new order, the comparatively recent existence of man as master of the whole globe, and the extinction of multitudes of living forms, are wonderful evidences and monuments of the revolutions to which the earth has been subjected, and afford grounds for the anticipation of future changes, to which in the progress of time our planet will be exposed, to such an extent as to lead to the destruction of the existing order, and give rise to new creations in some distant ages, possibly to the improvement even of the human species. But, whether any higher than man may be created, or the earth return to a more simple and less perfect system of organisation, it is impossible to conjecture; nor can we conceive, upon any reasonable ground, to what probable extent the future physical changes of the globe may influence either the destinies of man, the destruction of existing species of living beings, or the creation of new forms of animals and plants. Of the past history of the earth, we have abundant evidence from monuments of remote ages; the future we cannot contemplate without being lost in a chaos of conjecture and speculation. To this short and general sketch of the history of the earth, derived from geological data solely, some account of the living creation in connexion with the strata of the globe may be considered, as affording a view of the natural history of our planet, based upon the best possible foundations. In the prosecution of this inquiry it will be seen, that the causes now in operation are sufficient to account for the past changes to which the earth has been subjected from the earliest geological eras, however much these changes may have been occasionally accelerated by sudden and violent revolutions. Mr. Lyell, Professor of Geology at the King's College, has recently published a valuable work upon this subject, the facts of which are of the highest importance, as they tend to dissipate idle speculations that have been put forth upon the order and regularity of the great scheme of nature. One of the main points which this author has successfully established is, the existence of species in the animal and vegetable creation, not as a mere artificial mode of arrangement, but as existing absolutely in the natural grouping of animals and plants. Some naturalists have pretended that there is no such thing as species in nature, and that the whole system of organisation may be referred to a gradual development of living forms passing from one to another, in one continuous and uninterrupted chain, from the lowest being of the simplest construction to the highest, each grade being an evolution from the preceding. Such a transmutation of species was the foundation of Lamark's system, one which has been followed by some French philosophers, who adhered to the Lamarkian theory notwithstanding the geological facts which must have been known to them, and which were in direct contradiction of the theory which they chose to support. Their bias was to rob the Creator of one of his greatest attributes, by shewing that instead of a special intervention in the creation of animals and plants, fitted to the preparatory state of the earth, the entire scheme of nature was a mere evolution of organs and functions in succession, as existing physical circumstances called them forth, by a law of necessity growing out of matter, without the interference of the Deity. This was the doctrine of the materialists of the French school, and to which they subjected all their reasonings. Geological facts are, however, against them, and distinctly shew that at different epochs of the history of the earth different species were created fitted for the habitations provided for them, which species retain, throughout all the revolutions of the earth, their distinct and special characteristics, unchanged to the latest generations in all essential points, acquiring no new organs, and losing none of those originally given them, however modified their habits may be by the various transportations to which they are subject from the influence of man, of animals, and various physical causes in daily opera tion. By the term species is meant every collection of similar individuals produced by others like themselves, since every living individual bears a close resemblance to those from which it springs; and this is true both as to plants and animals. All individuals, in fact, propagated from one stock possess certain characters in common which never vary, and distinguish them from all others to the most remote generations, and which is destroyed only by the extinction of the species. But the Lamarkians profess to see no such distinctions; they affirm that all individuals pass from one to another progressively, confounding species and genera, and that mere varieties are obliged to be laid hold of in order to mark a gap in the chain, which they maintain is always filled up, and that genera are still less distinguishable than species. If, they say, you pass over a few links of the chain, you will not be able to recognise any being next brought into view, especially amongst domesticated animals, so completely are they changed. They pretend that the dog sprung from the wolf, in the scale of improvement, and is merely a wolf in a modified state from domestic circumstances; but that if these circumstances be suspended, he returns to the wolfish character. Now it is well known that the dog, under no circumstances, becomes a wolf, or any thing resembling it, but in the wildest state preserves his canine character, as a distinct species, maintaining in his conformation precisely the peculiarities of the original type. It is perfectly true that domestication, climate, and other causes, change the external characters of animals, which depends upon the organs chiefly called into use. But in no instance do we see any organ lost, or any new one added, in tracing an individual species. Animals have evidently been created successively with an organisation fitted to the circumstances of their position. Every analogy proves this fact. The feet of the dromedary and camel are so constructed as to bear the huge weight of the animal in walking over sandy deserts without distress, by an elastic ball adapted to the surface it is destined to move on; and this species is furnished with stomachs capable of holding a large quantity of water and herbaceous food, both of which are scarce in the sandy plains in which it dwells. But the Lamarkians explain such provisions by referring them to the local circumstances in which animals are placed, as the necessary causes of such peculiar developments of their organs. And thus it is that materialists reason, and with sophistry, and heedlessness of facts actually be fore them, deprive the Creator of the most beautiful instances of providential care and contrivance. The principal argument in favour of distinct species existing naturally, is derived from an aversion between the sexes of separate species to form alliances -a fact denied by Lamark, who supposes that such alliances do occur, and that offspring frequently proceed from them, both as to animals and plants, and that innumerable varieties arise in consequence. If, however, this view be correct, we must still have some point of departure; and in no instance where we can trace a pedigree do we find the original stem of the branches wanting. The geological monuments of the earth exhibit a graduated scale of organisation, from a simple plan to one of varied complexity. As each group appears from age to age, the organs added successively increase in dignity and importance, whilst no individual race is more completely developed than the one preceding it, although con structed upon an improved plan. Geology teaches us that plants and animals of the most simple known construction existed prior to more complicated forms, and that the globe was formed long before it was susceptible of life and fitted to maintain living beings. The chain of progressive improvement is beautifully demonstrated by geology, and appears to be so complete that there is scarcely a link missing. With many geological facts before him to the contrary, Lamark supposed the earth to be covered by the ocean after the commencement of organisation; and hence he assumes the priority of marine animals, the testace appearing first, and being gradually evolved into terrestrial animals. ancient idea was in opposition to this, for animals were considered as becoming deteriorated by being left to themselves, and that when it was otherwise the amelioration was a special intervention of the Deity. The Admitting that the modification of plants and animals from common parents has been indefinite, the most simple and imperfect forms must have constituted the original types. Upon this principle we must conceive inert matter first to have been endowed with simple vitality, until, in the course of ages, sensation was added, the senses subsequently acquired with their special organs, and the mental faculties developed, whereby the irrational being glided into the rational. And yet we now see beings of the simplest organisation, the infusoria and polypi, and the confervæ and other cryptogamous plants, associated with the highest orders of mammiferæ and vegetables. This is attempted to be accounted for by Mr. Lyell thus: "Nature is not intelligence, nor the Deity, but a delegated power under laws of necessity. She is obliged to go on gradually; she cannot produce animals and plants of |