 Chapter 9 Part 3 of Principles of Geology This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. The Absence of Cetacea, from Rocks Older than the Eocene, has been frequently adduced as lending countenance to the theory of the very late appearance of the highest class of vertebrata on the earth. Professor Sedgwick possesses in the Cambridge Museum a mass of ankylosed cervical vertebrae of a whale, which he found in drift clay near Elly, and which he has no doubt was washed out of the Kimmeridge clay, an upper member of the Oolite. According to Professor Owen, it exhibits well-marked specific characters, distinguishing it from all other known recent or fossil Cetacea. Dr. Letty, of Philadelphia, has lately described two species of Cetacea of a new genus, which he has called Priscodelfinas from the green sand of New Jersey, which corresponds in age with the English shock or the Cretaceous strata above the galt. The specimens consist of dorsal and cervical vertebrae, even in the Eocene strata of Europe. The discovery of cetaceans has never kept pace with that of land quadrupeds. The only instance cited in Great Britain is a species of monodon from the London clay of doubtful authenticity as to its geological position. On the other hand, the gigantic zeugladon of North America occurs abundantly in the Middle Eocene strata of Georgia and Alabama, from which as yet no bones of land quadrupeds have been obtained. In the present imperfect state then of our information, we can scarcely say more than that the Cetacea seems to have been scarce in the secondary and primary periods. It is quite conceivable that when Aquatic Saurians, some of them carnivorous, like the ichthyosaurus, were swarming in the sea and when there were large herbivorous reptiles like the iguanodon on the land, the class of reptiles may, to a certain extent, have superseded the Cetacea and discharged their functions in the animal economy. That mammalia had been created long before the epoch of the Kimmerich clay is shown by the microlestes of the trias before alluded to and by the stone's field quadrupeds from the inferior oolite, and we are bound to remember whenever we infer the poverty of the flora or fauna of any given period of the past from the small number of fossils occurring in ancient rocks that it has been evidently no part of the plan of nature to hand down to us a complete or systematic record of the former history of the animate world. We may have failed to discover a single shell, marine or freshwater, or a single coral, or bone in certain sandstones, such as that of the valley of the Connecticut, or the footprints of bipeds and quadrupeds abound, but such failure may have arisen not because the population of the land or sea was scanty at that era, but because in general the preservation of any relics of the animals or plants of former times is the exception to a general rule. Times so enormous as that contemplated by the geologist may multiply exceptional cases till they seem to constitute the rule, and so impose on the imagination as to lead us to infer the non-existence of creatures of which no monuments happen to remain. Professor Forbes has remarked that few geologists are aware how large a proportion of all known species of fossils are founded on single specimens, while a still greater number are founded on a few individuals discovered in one spot. This holds true not only in regard to animals and plants inhabiting the land, the lake, and the river, but even to a surprising number of marine mollusca, articulata, and radiata. Our knowledge, therefore, of the living creation of any given period of the past may be said to depend in a great degree on what we commonly call chance, and the casual discovery of some new localities rich in peculiar fossils may modify or entirely overthrow all our previous generalizations. Upon the whole, then, we derive this result from a general review of the fossils of the successive tertiary strata, namely that since the Eocene period there have been several great changes in the land quadrupeds inhabiting Europe, probably not less than five complete revolutions, during which there has been no step whatever made in advance, no elevation in the scale of being. So that had man been created at the commencement of the Eocene era, he would not have constituted a greater innovation on the state of the animal creation previously established than now, when we believe him to have begun to exist at the close of the Pliocene. The views, therefore, which I propose in the first edition of this work, January 1830, in opposition to the theory of progressive development, do not seem to me to require material modification, notwithstanding the large additions since made to our knowledge of fossil remains. These views may be thus briefly stated. From the earliest period at which plants and animals can be proved to have existed, there have been a continual change going on in the position of land and sea, accompanied by great fluctuations of climate. To these ever-varying geographical and climatical conditions, the state of the animate world has been unceasingly adapted. No satisfactory proof has yet been discovered of the gradual passage of the earth from a chaotic to a more habitable state, nor of any law of progressive development governing the extinction and renovation of species, and causing the fauna and flora to pass from an embryonic to a more perfect condition, from a single to a more complex organization. The principle of adaptation to which I have alluded appears to have been analogous to that which now peoples the arctic, temperate, and tropical regions contemporaneously with distinct assemblages of species and genera, or which, independently of mere temperature, gives rise to a predominance of the marsupial or didelphus tribe of quadrupedes in Australia, of the placental or monodelfus tribe in Asia and Europe, or which causes a profusion of reptiles without mammalia in the Galapagos Archipelago, and of mammalia without reptiles in Greenland, recent origin of man. If then, the popular theory of the successive development of the animal and vegetable world, from the simplest to the most perfect forms, rests on a very insecure foundation, it may be asked whether the recent origin of man lends any support to the same doctrine, or how far the influence of man may be considered as such a deviation from the analogy of the order of things previously established, as to weaken our confidence in the uniformity of the course of nature. Antisedently to investigation, we might reasonably have anticipated that the vestiges of man would have been traced back at least as far as those modern strata, in which all the testaceae and a certain number of the mammalia are of existing species. For of all the mammalia, the human species is the most cosmopolite and perhaps more capable than any other of surviving considerable vicissitudes in climate and in the physical geography of the globe. No inhabitant of the land exposes himself to so many dangers on the waters as man, whether in a savage or a civilized state. When there is no animal, therefore, whose skeleton is so liable to become embedded and lack astrene or submarine deposits. Nor can it be said that his remains are more perishable than those of other animals. For in ancient fields of battle, as Cuvier has observed, the bones of men have suffered as little decomposition as those of horses which were buried in the same grave. But even if the more solid parts of our species had disappeared, the impression of their form would have remained engraven on the rocks, as have the traces of the tinderous leaves of plants and the soft integuments of many animals, works of art, more ever, composed of the most indestructible materials, would have outlasted almost all the organic contents of sedimentary rocks, edifices, and even entire cities have, within the times of history, been buried under volcanic ejections, submerged beneath the sea, or engulfed by earthquakes. And had these catastrophes been repeated throughout an indefinite lapse of ages, the high antiquity of man would have been inscribed in far more legible characters on the framework of the globe than are the forms of the ancient vegetation which once covered the islands of the Northern Ocean, or of those gigantic reptiles which at still later periods peopled the seas and rivers of the Northern Hemisphere. Dr. Pritchard has argued that the human race have not always existed on the surface of the earth, because, quote, the strata of which our continents are composed were once a part of the ocean's bed. Mankind had a beginning, since we can look back to the period when the surface on which they lived began to exist, end quote. This proof, however, is insufficient, for many thousands of human beings now dwell in various quarters of the globe where marine species lived within the times of history and, on the other hand, the sea now prevails permanently over large districts once inhabited by thousands of human beings. Nor can this interchange of sea and land ever cease while the present causes are in existence. Terrestrial species, therefore, might be older than the continents which they inhabit, an aquatic species of higher antiquity than the lakes and seas which they now peopled. But so far as our interpretation of physical movements has yet gone, we have every reason to infer that the human race is extremely modern, even when compared to the larger number of species now are contemporaries on the earth, and we may, therefore, ask whether his creation can be considered as one step in a supposed progressive system by which the organic world has advanced slowly from a more simple to a more complex and perfect state. If we concede, for a moment, the truth of the proposition, that the sponge, the cephalopod, the fish, the reptile, the bird, and the mammoth have followed each other in regular chronological order, the creation of each class being separated from the other by vast intervals of time, should we be able to recognize in man's entrance upon the earth the last term of one in the same series of progressive developments? In reply to this question, it should first be observed that the superiority of man depends not on those faculties and attributes which he shares in common with the inferior animals, but on his reason by which he is distinguished from them. When it is said that the human race is of far higher dignity than were any pre-existing beings on the earth, it is the intellectual and moral attributes of our race, rather than the physical which are considered, and it is by no means clear that the organization of man is such as would confer a decided preeminence upon him if, in place of his reasoning powers, he was merely provided with such instincts as are possessed by the lower animals. If this be admitted, it would not follow, even if there were sufficient geological evidence in favor of the theory of progressive development, that the creation of man was the last link in the same chain. For the sudden passage from an irrational to irrational animal is a phenomenon of a distinct kind from the passage from the more simple to the more perfect forms of animal organization and instinct. To pretend that such a step, or rather leap, can be part of a regular series of changes in the animal world is to strain analogy beyond all reasonable bounds, introduction of man to what extent a change in the system. But setting aside the question of progressive development, another and a far more difficult one may arise out of the admission that man is comparatively of modern origin. It is not the interference of the human species, it may be asked. Such a deviation from the antecedent course of physical events, that the knowledge of such a fact tends to destroy all our confidence in the uniformity of the order of nature, both in regard to time past and future. If such an innovation could take place after the earth had been exclusively inhabited, or thousands of ages by inferior animals, why should not other changes as extraordinary and unprecedented happen from time to time? If one new cause was permitted to supervene, differing in kind and energy from any before in operation, why may not others have come into action at different epochs? Or what security have we that they may not arise here after? And if such be the case, how can the experience of one period, even though we are acquainted with all the possible effects of the thin existing causes, be a standard to which we can refer all natural phenomena of other periods? Now these objections would be unanswerable if adduced against one who was contending for the absolute uniformity throughout all time of the succession of subliminary events, if for example, it was disposed to indulge in the philosophical reveries of some Egyptian and Greek sects, who represented all the changes both of the moral and material world as repeated at distant intervals, so as to follow each other in their former connection of place and time. For they compared the course of events on our globe to astronomical cycles. And not only did they consider all subliminary affairs to be under the influence of the celestial bodies, but they taught that on the earth, as well as in the heavens, the same identical phenomena recurred again and again in a perpetual vicissitude. The same individual men were doomed to be reborn, and to perform the same actions as before, the same arts were to be invented, and the same cities built and destroyed. The Argonautic expedition was destined to sail again with the same heroes, and Achilles of his Mermidans to renew the combat for the walls of Troy. Haltere eritum tithes et altera quae vee hat argo delectos eroas. Erand etiam altera beila acque eterum ad trojan magnus miteter achilles. The geologist, however, they condemn these tenets as absurd, without running into the opposite extreme, and denying that the order of nature has, from the earliest periods, been uniform in the same sense in which we believe it to be uniform at present, and expect it to remain so in future. We have no reason to suppose that when man first became master of a small part of the globe, a greater change took place in its physical condition than is now experienced when districts, never before inhabited, become successfully occupied by new settlers. When a powerful European colony lands on the shores of Australia, and introduces at once those arts which it has required many centuries to mature when it imports a multitude of plants, and large animals from the opposite extremity of the earth, and begins rapidly to extirpate many of the indigenous species, a mightier revolution is effected in a brief period than the first entrance of a savage horde, or their continued occupation of the country for many centuries can possibly be imagined to have produced. If there be no impropriety in assuming that the system is uniform, when disturbances so unprecedented occur in certain localities, we can with much greater confidence apply the same language to those primeval ages, when they aggregate number and power for the human race, or the rate of their advancement in civilization, must be supposed to have been far inferior. In reasoning on the state of the globe immediately before our species was called into existence, we must be guided by the same rules of induction as when we speculate on the state of America in the interval that elapsed between the introduction of man into Asia, the supposed cradle of our race, and the arrival of the first adventurers on the shores of the new world. In that interval, we imagine the state of things to have gone on according to the order now observed in regions unoccupied by man. Even now, the waters of lakes, seas, and the great ocean, which team with life, may be said to have no immediate relation to the human race, to be portions of the terrestrial system of which man has never taken, nor ever can take possession, so that the greater part of the inhabited surface of the planet may still remain as insensible to our presence as before any isle or continent was appointed to be our residence. If the barren soil around Sydney had at once become fertile upon the landing of our first settlers, if, like the happy isles whereof the poets have given such glowing descriptions, those sandy tracks have begun to yield spontaneously an annual supply of grain. We might then, indeed, have fancied alterations still more remarkable in the economy of nature to have attended the first coming of our species into the planet. Or if, when a volcanic island like Ischia was, for the first time, brought under cultivation by the enterprise and industry of a Greek colony, the internal fire had become dormant and the earthquake had remitted its destructive violence. There would have been some ground for speculating on the debilitation of the subterranean forces when the earth was first placed under the dominion of man. But after a long interval of rest, the volcano bursts forth again with renewed energy, annihilates one half of the inhabitants, and compels the remainder to emigrate. A course of nature remains evidently unchanged, and, in like manner, we may suppose a general condition of the globe, immediately before and after the period when our species first began to exist, to have been the same, of the exception only of man's presence. The modifications in the system of which man is the instrument do not, perhaps, constitute so great a deviation from previous analogy as we usually imagine. We often, for example, form an exaggerated estimate of the extent of our power in exturbating some of the inferior animals, and causing others to multiply. A power which is circumscribed within certain limits, and which, in all likelihood, is by no means exclusively exerted by our species. The growth of human population cannot take place without diminishing the numbers, or causing the entire destruction of many animals. The larger beasts of prey, in particular, give way before us, but other quadrupeds of smaller size and innumerable birds, insects, and plants, which are inimical to our interests, increase in spite of us some attacking our food, others are raiment and persons, and others interfering with our agricultural and horticultural labours. We behold the rich harvest which we have raised by the sweat of our brow devoured by myriads of insects, and are often as incapable of arresting their depredations as of staying the shock of an earthquake or the course of a stream of lava. A great philosopher has observed that we can command nature only by obeying her laws, and this principle is true even in regard to the astonishing changes which are super-induced in the qualities of certain animals and plants by domestication and garden culture. I shall point out in the third book that we can only affect such surprising alterations by assisting the development of certain instincts, or by availing ourselves of that mysterious law of their organization by which individual peculiarities are transmissible from one generation to another. It is probable from these and many other considerations that as we enlarge our knowledge of the system we shall become more and more convinced that the alterations caused by the interference of man deviate far less from the analogy of those affected by other animals than is usually supposed. We are often misled when we institute such comparisons by our knowledge of the wide distinction between the instincts of animals and the reasoning power of man, and we are apt hastily to infer that the effects of a rational and irrational species, considered merely as physical agents, will differ almost as much as the faculties by which their actions are directed. It is not, however, intended that a real departure from the antecedent course of physical events cannot be traced in the introduction of man. If that latitude of action which enables the brutes to accommodate themselves in some measure to accidental circumstances could be imagined to have been at any form or period so great that the operations of instinct were as much diversified as are those of human reason, it might, perhaps, be contended that the agency of man did not constitute in anomalous deviation from the previously established order of things. It might have been said that the Earth's becoming at a particular period the residence of human beings was an era in the moral, not in the physical world, that our study and contemplation of the Earth and the laws which govern its animate productions ought no more to be considered in the light of a disturbance or deviation from the system than the discovery of the satellites of Jupiter should be regarded as a physical event affecting those heavenly bodies. Their influence in advancing the progress of science among men and in aiding navigation and commerce was accompanied by no reciprocal action of the human mind upon the economy of nature in those distant planets and so the Earth might be conceived to have become, at a certain period, a place of moral discipline and intellectual improvement to man without the slightest arrangement of a previously existing order of change in its animate and inanimate productions. The distinctness, however, of the human from all other species considered merely as an efficient cause in the physical world, is real. For we stand in a relation to contemporary species of animals and plants widely different from that which other irrational animals can ever be supposed to have held to each other. We modify their instincts, relative numbers, and geographical distribution in a manner superior in degree and in some respects very different in kind from that in which any other species can affect the rest. Besides, the progressive movement of each successive generation of men causes the human species to differ more from itself in power at two distant periods than any one species of a higher order of animals differs from another. The establishment, therefore, by geological evidence of the first intervention of such a peculiar and unprecedented agency, long after other parts of the animate and inanimate world existed, affords grounds for concluding that the experience during thousands of ages of all the events which may happen on this globe would not enable a philosopher to speculate with confidence concerning future contingencies. If, then, an intelligent being, after observing the order of events for an indefinite series of ages, had witnessed at last so wonderful an innovation as this, to what extent would his belief in the regularity of the system be weakened? Would he cease to assume that there was permanency in the laws of nature? Would he no longer be guided in his speculations by the strictest rules of induction? To these questions that may be answered that, had he previously presumed to dogmatize respecting the absolute uniformity of the order of nature, he would undoubtedly be checked by witnessing this new and unexpected event, and would form a more just estimate of the limited range of his own knowledge, and the unbounded extent of the scheme of the universe. But he would soon perceive that no one of the fixed and constant laws of the animate or inanimate world was subverted by human agency, and that the modifications now introduced for the first time were the accompaniments of new and extraordinary circumstances, and those not of a physical but of a moral nature. The deviation permitted would also appear to be as slight as was consistent with the accomplishment of the new moral ends proposed, and to be in a great degree temporary in its nature, so that whenever the power of the new agent was withheld, even for a brief period, a relapse would take place to the ancient state of things, the domesticated animal, for example, recovering in a few generations its wild instinct, and the garden flower and fruit tree reverting to the likeness of the parent's stock. Now, if it would be reasonable to draw such inferences with respect to the future, we cannot but apply the same rules of induction to the past. We have no right to anticipate any modifications in the results of existing causes in time to come, which are not conformable to analogy, unless they be produced by the progressive development of human power, or perhaps by some other new relations, which may hereafter spring up between the moral and material worlds. In the same manner, when we speculate on the vicissitudes of the animate and inanimate creation in former ages, we ought not to look for any anomalous results, unless where man has interfered, or unless clear indications appear of some other moral source of temporary derangement. For more information or to volunteer, please visit LibriVox.org, recording by Deon Jines, Salt Lake City, Utah. Principles of Geology by Charles Lyall, Chapter 10, Supposed Intensity of Aqueous Forces at Remote Periods Intensity of Aqueous Causes Slow Accumulation of Strata Proved by Fossils Rate of denudation can only keep pace with deposition, erratics and effects of ice, deluges, and the causes to which they are referred, supposed universality of ancient deposits. Intensity of Aqueous Causes The great problem considered in the preceding chapters, namely whether the former changes of the earth made known to us by geology resemble in kind and degree, those now in daily progress may still be contemplated from several other points of view. We may inquire, for example, whether there are any grounds for the belief entertained by many, that the intensity, both of aqueous and of igneous forces in remote ages, far exceeded that which we witness in our own time, first then as to aqueous causes. It has been shown in our history of the science that Woodward did not hesitate in 1695 to teach that the entire mass of fossiliferous strata contained in the earth's crust had been deposited in a few months and consequently as their mechanical and derivative origin was already admitted, the reduction of rocky masses into mud, sand and pebbles, the transportation of the same to a distance, and their accumulation elsewhere in regular strata were all assumed to have taken place with a rapidity unparalleled in modern times. This doctrine was modified by degrees in proportion as different classes of organic remains such as shells, corals, and fossil plants had been studied with attention. Analogy led every naturalist to assume that each full-grown individual of the animal or vegetable kingdom had required a certain number of months or years for the attainment of maturity and the perpetuation of its species by generation, and thus the first approach was made to the conception of a common standard of time without which there are no means whatever of measuring the comparative rate at which any succession of events has taken place at two distinct periods. This standard consisted of the average duration of the lives of individuals of the same genera or families in the animal and vegetable kingdoms and the multitude of fossils dispersed through successive strata implied the continuance of the same species for many generations. At length the idea that species themselves had had a limited duration arose out of the observed fact that sets of strata of different ages contained fossils of distinct species. Finally, finally the opinion became general that in the course of ages one assemblage of animals and plants had disappeared after another again and again and new tribes had started into life to replace them. Denudation, in addition to the proofs derived from organic remains the forms of stratification led also on a fuller investigation to the belief that sedimentary rocks had been slowly deposited but it was still supposed that denudation or the power of running water and the waves and currents of the ocean to strip off superior strata and lay bare the rocks below had formerly operated with an energy wholly unequaled in our times. These opinions were both illogical and inconsistent because deposition and denudation are parts of the same process and what is true of the one must be true of the other. Their speed must be always limited by the same causes and the conveyance of solid matter to a particular region can only keep pace with its removal from another so that the aggregate of sedimentary strata in the earth's crust can never exceed in volume the amount of solid matter which has been ground down and washed away by running water. How vast then must be the spaces which this abstraction of matter has left vacant? How far exceeding in dimensions all the valleys however numerous and the hollows however vast which we can prove to have been cleared out by aqueous erosion. The evidences of the work of denudation are defective because it is the nature of every destroying cause to obliterate the signs of its own agency but the amount of reproduction in the form of sedimentary strata must always afford a true measure of the minimum of denudation which the earth's surface has undergone erratics. The next phenomenon to which the advocates of the excessive power of running water in times past have appealed is the enormous size of the blocks called erratic which lie scattered over the northern parts of europe and north america unquestionably a large proportion of these blocks have been transported far from their original position for between them and the parent rocks we now find not infrequently deep seas and valleys intervening or hills more than a thousand feet high. To explain the present situation of such traveled fragments a deluge of mud has been imagined by some to have come from the north bearing along with it sand gravel and stony fragments some of them hundreds of tons in weight this flood in its transient passage over the continents dispersed the boulders irregularly over hill valley and plain or forced them along over a surface of hard rock so as to polish it and leave it indented with parallel scratches and grooves such markings as are still visible in the rocks of scandinavia scotland canada and many other countries there can be no doubt that the myriads of angular and rounded blocks above alluded to cannot have been born along by ordinary rivers or marine currents so great is their volume and weight and so clear are the signs in many places of time having been occupied in their successive deposition for they are often distributed at various depths through heaps of regularly stratified sand and gravel no waves of the sea raised by earthquakes nor the bursting of lakes dammed up for a time by landslips or by avalanches of snow can account for the observed facts but i shall endeavor to show in the next book chapter 15 that a combination of existing causes may have conveyed erratics into their present situations the causes which will be referred to are first the carrying power of ice combined with that of running water and second the upward movement of the bed of the sea converting it gradually into land without entering at present into any details respecting these causes i may mention that the transportation of blocks by ice is now simultaneously in progress in the cold and temperate latitudes both of the northern and southern hemisphere as for example on the coast of canada and gulf of st laurance and also in chili patagonia and the island of south georgia in those regions the uneven bed of the ocean is becoming strewed over with ice drifted fragments which have either stranded on shoals or been dropped in deep water by melting bergs the entanglement of boulders in drift ice will also be shown to occur annually in north america and these stones when firmly frozen into ice wander year after year from labrador to the st laurance and reach points of the western hemisphere farther south than any part of great britain the general absence of erratics in the warmer parts of the equatorial regions of asia africa and america confirms the same views as to the polishing and grooving of hard rocks it has lately been ascertained that glaciers give rise to these effects when pushing forward sand pebbles and rocky fragments and causing them to grate along the bottom nor can there be any reasonable doubt that icebergs when they run aground on the floor of the ocean must imprint similar marks upon it it is unnecessary therefore to refer to deluges or even to speculate on the former existence of a climate more severe than that now prevailing in the western hemisphere to explain the geographical distribution of most of the european erratics deluges as deluges have been often alluded to i shall say something of the causes which may be supposed to give rise to these grand movements of water in addition to those already alluded to geologists who believe that mountain chains have been thrown up suddenly at many successive epics imagine that the waters of the ocean may be raised by these convulsions and then break in terrific waves upon the land sweeping over whole continents hollowing out valleys and transporting sand gravel and erratics to great distances the sudden rise of the alps or andes it is said may have produced a flood even subsequently to the time when the earth became the residence of man but it seemed strange that none of the riders who have indulged their imaginations in conjectures of this kind should have ascribed a deluge to the sudden conversion of part of the unfathomable ocean into a shoal rather than to the rise of mountain chains in the latter case the mountains themselves could do no more than displace a certain quantity of atmospheric air whereas the instantaneous formation of the shoal would displace a vast body of water which being heaved up to a great height might roll over and permanently submerge a large portion of a continent if we restrict ourselves to combinations of causes at present known it would seem that the two principal sources of extraordinary inundations are first the escape of the waters of a large lake raised far above the sea and secondly the pouring down of a marine current into lands depressed below the mean level of the ocean as an example of the first of these cases we may take lake superior which is more than 400 geographical miles in length and about 150 in breadth having an average depth of from 500 to 900 feet the surface of this vast body of fresh water is no less than 600 feet above the level of the ocean the lowest part of the barrier which separates the lake on its southwest side from those streams which flow into the head waters of the Mississippi being about 600 feet high if therefore a series of subsidences should lower any part of this barrier 600 feet any subsequent rending or depression even of a few yards at a time would allow the sudden escape of vast floods of water into a hydrographical basin of enormous extent if the event happened in the dry season when the ordinary channels of the Mississippi and its tributaries are in a great degree empty the inundation might not be considerable but if in the flood season a region capable of supporting a population of many millions might be suddenly submerged but even this event would be insufficient to cause a violent rush of water and to produce those effects usually called deluvial for the difference of level of 600 feet between lake superior and the Gulf of Mexico when distributed over a distance of 1800 miles would give an average fall of only four inches per mile the second case before adverted to is where there are large tracks of dry land beneath the mean level of the ocean it seems after much controversy to be at length a settled point that the Caspian is really 83 feet six inches lower than the Black Sea as the Caspian covers an area about equal to that of Spain and as its shores are in general low and flat there must be many thousand square miles of country less than 83 feet above the level of that inland sea and consequently depressed below the Black Sea and Mediterranean this area includes the site of the populous city of Astrakhan and other towns into this region the ocean would pour its waters if the land now intervening between the sea of Azoth and the Caspian should subside yet even if this event should occur it is most probable that the submergence of the whole region would not be accomplished simultaneously but by a series of minor floods the sinking of the barrier being gradual supposed universality of ancient deposits the next fallacy which has helped to perpetuate the doctrine that the operations of water were on a different and grander scale in ancient times is founded on the indefinite areas over which homogeneous deposits were supposed to extend no modern sedimentary strata it is said equally identical in mineral character and fossil contents can be traced continuously from one quarter of the globe to another but the first propagators of these opinions were very slightly acquainted with the inconstancy in mineral composition of the ancient formations and equally so of the wide spaces over which the same kind of sediment is now actually distributed by rivers and currents in the course of centuries the persistency of character in the older series was exaggerated its extreme variability in the newer was assumed without proof in the chapter which treats of river deltas and the dispersion of sediment by currents and in the description of reefs of coral now growing over areas many hundred miles in length i shall have opportunities of convincing the reader of the danger of hasty generalizations on this head in regard to the imagined universality of particular rocks of ancient date it was almost unavoidable that this notion when once embraced should be perpetuated for the same kinds of rocks have occasionally been reproduced at successive epics and when once the agreement or disagreement in mineral character alone was relied on as the test of age it followed that similar rocks if found even at the antipathy were referred to the same era until the contrary could be shown now it is usually impossible to combat such an assumption on geological grounds so long as we are imperfectly acquainted with the order of superposition and the organic remains of these same formations thus for example a group of red moral and red sandstone containing salt and gypsum being interposed in england between the lias and the coal all other red morals and sandstones associated some of them with salt and others with gypsum and occurring not only in different parts of europe but in north america peru india the salt deserts of asia those of africa in a word in every quarter of the globe were referred to one and the same period the burden of proof was not supposed to rest with those who insisted on the identity in age of all these groups their identity in mineral composition was thought sufficient it was in vain to urge as an objection the improbability of the hypothesis which implies that all the moving waters on the globe were once simultaneously charged with sediment of a red color but the rashness of pretending to identify in age all the red sandstones and marbles in question has at length been sufficiently exposed by the discovery that even in europe they belong decidedly to many different epics it is already ascertained that the red sandstone and red marl containing the rock salt of cardona in catalonia is newer than the olytic if not more modern than the cretaceous period it is also known that certain red marls and variegated sandstones in auverne which are undistinguishable in mineral composition from the new red sandstone of english geologists belong nevertheless to the eocene period and lastly the gypsius red marl of eggs in province formerly supposed to be a marine secondary group is now acknowledged to be a tertiary freshwater formation in novus kosher one great deposit of red marl sandstone and gypsum precisely resembling in mineral character the new red of england occurs as a member of the carboniferous group and in the united states near the falls of niagra a similar formation constitutes a subdivision of the salurian series nor was the nomenclature commonly adopted in geology without its influence in perpetuating the erroneous doctrine of universal formations such names for example as chalk green sand oolite red marl coal and others were given to some of the principal fossiliferous groups in consequence of mineral peculiarities which happened to characterize them in the countries where they were first studied when geologists had at length shown by means of fossils and the order of superposition that other strata entirely dissimilar in color texture and composition were of contemporaneous date it was thought convenient still to retain the old names that these were often inappropriate was admitted but the student was taught to understand them in no other than a chronological sense so that the chalk might not be a white cretaceous rock but a hard dolomitic limestone as in the alps or a brown sandstone or green marl as in new jersey us in like manner the green sand it was said might in some places be represented by red sandstone red marl salt and gypsum as in the north of spain so the oolitic texture was declared to be rather an exception than otherwise to the general rule in rocks of the oolitic period and it often became necessary to affirm that no particle of carbonaceous matter could be detected in districts where the true coal series abounded in spite of every precaution the habitual use of this language could scarcely fail to instill into the mind of the pupil an idea that chalk coal salt red marl or the oolitic structure were far more widely characteristic of the rocks of a given age than was really the case there is still another cause of deception disposing us to ascribe a more limited range to the newer sedimentary formations as compared to the older namely the very general concealment of the newer strata beneath the waters of lakes and seas and the wide exposure above waters of the more ancient the chalk for example now seen stretching for thousands of miles over different parts of europe has become visible to us by the effect not of one but of many distinct series of subterranean movements time has been required and a succession of geological periods to raise it above the waves in so many regions and if calcarius rocks of the middle and upper tertiary periods have been formed as homogeneous in mineral composition throughout equally extensive regions it may require convulsions as numerous as all those which have occurred since the origin of the chalk to bring them up within the sphere of human observation hence the rocks of more modern periods may appear partial as compared to those of remote eras not because of any original inferiority in their extent but because there has not been sufficient time since their origin for the development of a great series of elevatory movements in regard however to one of the most important characteristics of sedimentary rocks their organic remains many naturalists of high authority have maintained that the same species of fossils are more uniformly distributed through formations of high antiquity than in those of more modern date and that distinct zoological and botanical provinces as they are called which forms so striking a feature in the living creation were not established at remote eras thus the plants of the coal the shells the trilobites of the solarian rocks and the ammonites of the oolite have been supposed to have a wider geographical range than any living species of plants crustaceans or mollusks this opinion seems in certain cases to be well founded especially in relation to the plants of the carboniferous epoch owing probably to the more uniform temperature of the globe at a time when the position of sea and land was less favorable to variations in climate according to principles already explained in the seventh and eighth chapters but a recent comparison of the fossils of north american rocks with those of corresponding ages in the european series has proved that the terrestrial vegetation of the carboniferous epoch is an exception to the general rule and that the fauna and flora of the earth at successive periods from the oldest solarian to the newest tertiary was as diversified as now the shells corals and other classes of organic remains demonstrate the fact that the earth might then have been divided into separate zoological provinces in a manner analogous to that observed in the geographical distribution of species now living end of chapter 10 chapter 11 part 1 of principles of geology this is a libervox recording a libervox recordings are in the public domain for more information or to volunteer please visit libervox.org recording by deon gines selic city utah principles of geology by charles lyle chapter 11 part 1 on the supposed former intensity of the igneous forces volcanic action at successive geological periods plutonic rocks of different ages gradual development of subterranean movements faults doctrine of the sudden upheaval of parallel mountain chains objections to the proof of the suddenness of the upheaval and the contemporaneousness of parallel chains trains of active volcanoes not parallel as large tracks of land are rising or sinking slowly so narrow zones of land may be pushed up gradually to great heights bending of strata bilateral pressure adequacy of the volcanic power to affect this without paroxymal convulsions when reasoning on the intensity of volcanic action at former periods as well as on the power of moving water already treated of geologists have ever been prone to represent nature as having been prodigal of violence and parsimonious of time now although it is less easy to determine the relative ages of the volcanic than of the fossiliferous formations it is undeniable that igneous rocks have been produced at all geological periods or as often as we find distinct deposits marked by peculiar animal and vegetable remains it can be shown that rocks commonly called trapean have been injected into fissures and ejected at the surface both before and during the deposition of the carboniferous series and at the time when the magnesium limestone and when the upper new red sandstone were formed or when the lia's oolite green sand chalk and the several tertiary groups newer than the chalk originated in succession nor is this all distinct volcanic products may be referred to the subordinate divisions of each period such as the carboniferous as in the county of Fife in scotland where certain masses of contemporaneous trap are associated with the lower others with the upper coal measures and if one of these masses is more minutely examined we find it to consist of the products of a great many successive outbursts by which scoriae and lava were again and again emitted and afterwards consolidated then fissured and finally traversed by melted matter constituting what are called dykes as we enlarge therefore our knowledge of the ancient rocks formed by subterranean heat we find ourselves compelled to regard them as the aggregate effects of innumerable eruptions each of which may have been comparable in violence to those now experienced in volcanic regions it may indeed be said that we have as yet no data for estimating the relative volume of matter simultaneously in a state of fusion at two given periods as if we were to compare the columnar basalt of stafa and its environs with the lava poured out in iceland in 1783 but for this very reason it would be rash and unphilosophical to assume an excess of ancient as contrasted with modern outpourings of melted matter at particular periods of time it would be still more presumptuous to take for granted that the more deep-seated effects of subterranean heat surpassed at remote eras the corresponding effects of internal heat in our own times certain porphyries and granites and all the rocks commonly called plutonic are now generally supposed to have resulted from the slow cooling of materials fused and solidified under great pressure and we cannot doubt that beneath existing volcanoes there are large spaces filled with melted stone which must for centuries remain in an incandescent state and then cool and become hard and crystalline when the subterranean heat shall be exhausted that lakes of lava are continuous for hundreds of miles beneath the chilean andes seems established by observations made in the year 1835 now wherever the fluid contents of such reservoirs are poured out successively from craters in the open air or at the bottom of the sea the matter so ejected may afford evidence by its arrangement of having originated at different periods but if the subterranean residue after the withdrawal of the heat be converted into crystalline or plutonic rock the entire mass may seem to have been formed at once however countless the ages required for its fusion and subsequent refrigeration as the idea that all the granite in the earth's crust was produced simultaneously and in a primitive state of the planet has now been universally abandoned so the suggestion above adverted to may put us on our guard against too readily adopting another opinion namely that each large mass of granite was generated in a brief period of time modern writers indeed of authority seem more and more agreed that in the case of granitic rocks the passage from a liquid or pasty to a solid and crystalline state must have been an extremely gradual process the doctrine so much insisted upon formerly that crystalline rocks such as granite, nese, mica, schist, quartzite, and others were produced in the greatest abundance in the earlier ages of the planet and that their formation has seized altogether in our own times will be controverted in the next chapter gradual development of subterranean movements the extreme violence of the subterranean forces in remote ages has been often inferred from the facts that the older rocks are more fractured and dislocated than the newer but what other result could we have anticipated if the quantity of movement had been always equal in equal periods of time time must in that case multiply the derangement of strata in the ratio of their antiquity indeed the numerous exceptions to the above rule which we find in nature present at first sight the only objection to the hypothesis of uniformity for the more ancient formations remain in many places horizontal while in others much newer strata are curved and vertical this apparent anomaly however will be seen in the next chapter to depend on the irregular manner in which the volcanic and subterranean agency affect different parts of the earth in succession being often renewed again and again in certain areas while others remain during the whole time at rest that the more impressive effects of subterranean power such as the upheaval of mountain chains may have been due to multiplied convulsions of moderate intensity rather than to a few paroxysmal explosions will appear the less improbable when the gradual and intermittent development of volcanic eruptions in times past is once established it is now very generally conceited that these eruptions have their source in the same causes as those which give rise to the permanent elevation and sinking of land the admission therefore that one of the two volcanic or subterranean processes has gone on gradually draws with it the conclusion that the effects of the other have been elaborated by successive and gradual efforts faults the same reasoning is applicable to great faults or those striking instances of the upthrow or downthrow of large masses of rock which have been thought by some to imply tremendous catastrophes wholly foreign to the ordinary course of nature thus we have in england faults in which the vertical displacement is between 600 and 3000 feet and the horizontal extent 30 miles or more the width of the fissures since filled up with rubbish varying from 10 to 50 feet but when we inquire into the proofs of the mass having risen or fallen suddenly on the one side of these great rents several hundreds or thousands of feet above or below the rock with which it was once continuous on the other side we find the evidence defective there are grooves it is said and scratches on the rubbed and polished walls which have often one common direction favoring the theory that the movement was accomplished by a single stroke and not by a series of interrupted movements but in fact the straya are not always parallel in such cases but often irregular and sometimes the stones and earth which are in the middle of the fault or fissure have been polished and striated by friction in different directions showing that there have been slidings subsequent to the first introduction of the fragmentary matter nor should we forget that the last movement must always tend to obliterate the signs of previous triteration so that neither its instantaneousness nor the uniformity of its direction can be inferred from the parallelism of the straya that have been last produced when rocks have been once fractured and freedom of motion communicated to detached portions of them these will naturally continue to yield in the same direction if the process of upheaval or of undermining be repeated again and again the incumbent mass will always give way along the lines of leased resistance or where it was formally rent asunder probably the effects of reiterated movement whether upward or downward in a fault may be undistinguishable from those of a single and instantaneous rise or subsidence and the same may be said of the rising or falling of continental masses such as sweden or greenland which we know to take place slowly and insensibly doctrine of the sudden upheaval of parallel mountain chains the doctrine of the suddenness of many former revolutions in the physical geography of the globe has been thought by some to derive additional confirmation from a theory respecting the origin of mountain chains advanced in 1833 by a distinguished geologist M. Elia de Beaumont in several essays on this subject the last published in 1852 he has attempted to establish two points first that a variety of independent chains of mountains have been thrown up suddenly at particular periods and secondly that the contemporaneous chains thus thrown up preserve a parallelism the one to the other these opinions and others by which they are accompanied are so adverse to the method of interpreting the history of geological changes which I have recommended in this work that I am desirous of explaining the grounds of my descent a course which I feel myself the more called upon to adopt as the generalizations alluded to are those of a skillful writer and an original observer of great talent and experience I shall begin therefore by giving a brief summary of the principal propositions laid down in the works above referred to first M. de Beaumont supposes that in the history of the earth there have been long periods of comparative repose during which the deposition of sedimentary matter has gone on in regular continuity and there have also been short periods of paroxymal violence during which that continuity was broken secondly at each of these periods of violence or revolution in the state of the earth's surface a great number of mountain chains have been formed suddenly thirdly the chains thrown up by a particular revolution have one uniform direction being parallel to each other within a few degrees of the compass even when situated in remote regions whilst the chains thrown up at different periods have for the most part different directions fourthly each revolution or great convulsion has fallen in with the date of another geological phenomenon namely the passage from one independent sedimentary formation to another characterized by a considerable difference in organic types fifthly there has been a recurrence of these paroxymal movements from the remotest geological periods and they may still be reproduced and the repose in which we live may hereafter be broken by the sudden upthrow of another system of parallel chains of mountains sixthly the origin of these chains depends not on partial volcanic action or a reiteration of ordinary earthquakes but on the secular refrigeration of the entire planet for the whole globe with the exception of a thin envelope much thinner in proportion than the shell to an egg is a fused mass kept fluid by heat but constantly cooling and contracting its dimensions the external crust does not gradually collapse and accommodate itself century after century to the shrunken nucleus subsiding as often as there is a slight failure of support but it is sustained throughout whole geological periods so as to become partially separated from the nucleus until at last it gives way suddenly cracking and falling in along determinant lines of fracture during such a crisis the rocks are subjected to great lateral pressure the unyielding ones are crushed and the pliant strata bent and are forced to pack themselves more closely into a smaller space having no longer the same room to spread themselves out horizontally at the same time a large portion of the mass is squeezed upwards because it is in the upward direction only that the excess in size of the envelope as compared to the contracted nucleus can find relief this excess produces one or more of those folds or wrinkles in the earth's crust which we call mountain chains lastly some chains are comparatively modern such as the Alps which were partly upheaved after the middle tertiary period the elevation of the Andes was much more recent and was accompanied by the simultaneous outburst for the first time of 270 of the principal volcanoes now active the agitation of the waters of the ocean caused by this convulsion probably occasioned that transient and general deluge which is noticed in the traditions of so many nations several of the topics enumerated in the above summary such as the cause of interruptions in the sedimentary series will be discussed in the 13th chapter and I shall now confine myself to what I conceive to be the insufficiency of the proofs adduced in favor of the suddenness of the upthrow and the contemporaneousness of the origin of the parallel chains referred to at the same time I may remark that the great body of facts collected together by de Beaumont will always form a most valuable addition to our knowledge tending as they do to confirm the doctrine that different mountain chains have been formed in succession and as Werner first pointed out that there are certain determinant lines of direction or strike in the strata of various countries the following may serve as an analysis of the evidence on which the theory above stated depends we observe says em de Beaumont when we attentively examine nearly all mountain chains that the most recent rocks extend horizontally up to the foot of such chains as we should expect would be the case if they were deposited in seas or lakes of which these mountains have partly formed the shores whilst the other sedimentary beds tilted up and more or less contorted on the flanks of the mountains rise in certain points even to their highest crusts there are therefore in and adjacent to each chain two classes of sedimentary rocks the ancient and inclined beds and the newer or horizontal it is evident that the first appearance of the chain itself was an event intermediate between the period when the beds now upraised were deposited and the period when the strata were produced horizontally at its feet thus the chain a assumed its present position after the deposition of the strata b which have undergone great movements and before the deposition of the group c in which the strata have not suffered derangement if we then discover another chain b in which we find not only the formation b but the group c also disturbed and thrown on its edges we may infer that the latter chain is of subsequent date to a for b must have been elevated after the deposition of c and before that of the group d whereas a had originated before the strata c were formed it is then argued that in order to ascertain whether other mountain ranges are of contemporaneous date with a and b or are referable to distinct periods we have only to inquire whether the inclined and undisturbed sets of strata in each range correspond with or differ from those in the typical chain a and b now all this reasoning is perfectly correct so long as the period of time required for the deposition of the strata b and c is not made identical in duration with the period of time during which the animals and plants found fossil in b and c may have flourished for the latter that is to say the duration of certain groups of species may have greatly exceeded and probably did greatly exceed the former or the time required for the accumulation of certain local deposits such as b and c figures 11 and 12 in order moreover to render the reasoning correct do latitude must be given to the term contemporaneous for this term must be understood to allude not to a moment of time but to the interval whether brief or protracted which elapsed between two events namely between the accumulation of the inclined and that of the horizontal strata but unfortunately no attempt has been made in the treatises under review to avoid this manifest source of confusion and hence the very terms of each proposition are equivocal and the possible length of some of the intervals is so vast that to affirm that all the chains raised in such intervals were contemporaneous is an abuse of language in order to illustrate this argument I shall select the Pyrenees as an example originally M. E. de Beaumont spoke of this range of mountains as having been uplifted suddenly ah un sol jet but he has since conceded that in this chain in spite of the general unity and simplicity of its structure six if not seven systems of dislocation of different dates can be recognized in reference however to the latest and by far the most important of these convulsions the chain is said to have attained its present elevation at a certain epoch in the earth's history namely between the depositation of the chalk or rocks of about that age and that of certain tertiary formations as old as the plastic clay for the chalk is seen in vertical curved and distorted beds on the flanks of the chain as the beds be figure 11 while the tertiary formations rest upon them in horizontal strata at its base as C. Ibit the proof then of the extreme suddenness of the convulsion is supposed to be the shortness of the time which intervened between the formation of the chalk and the origin of certain tertiary strata even if the interval were deducible within these limits it might comprise an indefinite lapse of time in strictness of reasoning however the author cannot exclude the Cretaceous or tertiary periods from the possible duration of the interval during which the elevation may have taken place for in the first place it cannot be assumed that the movement of upheaval took place after the close of the Cretaceous period we can merely say that it occurred after the deposition of certain strata of that period secondly although it were true that the event happened before the formation of all the tertiary strata now at the base of the Pyrenees it would by no means follow that it preceded the whole tertiary epic the age of the strata both of the inclined and horizontal series may have been accurately determined by M. de Beaumont and still the upheaving of the Pyrenees may have been going on before the animals of the chalk period such as our found fossil in England had ceased to exist or when the maestrict beds were in progress or during the indefinite ages which may have elapsed between the extinction of the maestrict animals and the introduction of the Eocene tribes or during the Eocene epic or the rise may have been going on throughout one or several or all of these periods it would be a purely gratuitous assumption to say that the inclined Cretaceous strata B. figure 11 on the flanks of the Pyrenees were the very last which were deposited during the Cretaceous period or that as soon as they were upheaved all or nearly all the species of animals and plants now found fossil in them were suddenly exterminated yet unless this can be affirmed we cannot say that the Pyrenees were not upheaved during the Cretaceous period consequently another range of mountains at the base of which Cretaceous rocks may lie in horizontal stratification may have been elevated like the chain a figure 12 during some part of the same great period end of chapter 11 part 1 chapter 11 part 2 of principles of geology this is a LibriVox recording a LibriVox recordings are in the public domain for more information or to volunteer please visit LibriVox.org recording by Dion Giants Salt Lake City Utah principles of geology by Charles Lyle chapter 11 part 2 there are mountains in Sicily two or three thousand feet high the tops of which are composed of limestone in which a large proportion of the fossil shells agrees specifically with those now inhabiting the Mediterranean however as in many other countries the deposits now in progress in the sea must enclose shells and other fossils specifically identical with those of the rocks constituting the contiguous land so there are islands in the pacific where a mass of dead coral has emerged to a considerable altitude while other portions of the mass remain beneath the sea still increasing by the growth of living zoophytes and shells the chalk of the Pyrenees therefore may at a remote period have been raised to an elevation of several thousand feet while the species found fossil in the same chalk still continued to be represented in the fauna of the neighboring ocean in a word we cannot assume that the origin of a new range of mountains caused the Cretaceous period to cease and served as the prelude to a new order of things in the animate creation to illustrate the grave objections above advanced against the theory considered in the present chapter let us suppose that in some country three styles of architecture had prevailed in succession each for a period of one thousand years first the Greek then the Roman and then the Gothic and that a tremendous earthquake was known to have occurred in the same district during one of the three periods a convulsion of such violence as to have leveled to the ground all the buildings then standing if an antiquary desirous of discovering the date of the catastrophe should first arrive at a city where several Greek temples were lying in ruins and half engulfed in the earth while many gothic edifices were standing uninjured could he determine on these data the era of the shock could he even exclude any one of the three periods and decide that it must have happened during one of the other two certainly not he could merely affirm that it happened at some period after the introduction of the Greek style and before the gothic had fallen into disuse should he pretend to define the date of the convulsion with greater precision and decide that the earthquake must have occurred after the Greek and before the gothic period that is to say when the roman style was in use the fallacy in his reasoning would be too palpable to escape detection for a moment yet such is the nature of the erroneous induction which i am now exposing for as in the example above proposed the erection of a particular edifice is perfectly distinct from the period of architecture in which it may have been raised so is the deposition of chalk or any other set of strata from the geological epics characterized by certain fossils to which they may belong it is almost superfluous to enter into any farther analysis of the theory of parallelism because the whole force of the argument depends on the accuracy of the data by which the contemporaneous or non-contemporaneous date of the elevation of two independent chains can be demonstrated in every case this evidence as stated by m debaumont is equivocal because he has not included in the possible interval of time between the deposition of the deranged and the horizontal formations part of the periods to which each of those classes of formations are referable even if all the geological facts therefore adduced by the author were true and unquestionable yet the conclusion that certain chains were or were not simultaneously upraised is by no means a legitimate consequence in the third volume of my first edition of the principles which appeared in april 1833 i controverted the views of m debaumont then just published in the same terms as i have now restated them at that time i took for granted that the chronological date of the newest rocks entering into the disturbed series of the Pyrenees had been correctly ascertained it now appears however that some of the most modern of those disturbed strata belong to the pneumolytic formation which are regarded by the majority of geologists as eocene or older tertiary an opinion not ascended to by m e debaumont and which i cannot discuss here without being led into too long a digression perhaps a more striking illustration of the difficulties we encounter when we attempt to apply the theory under consideration even to the best known european countries is afforded by what is called the system of the longmans this small chain situated in shropshire is the third of the typical systems to which m e debaumont compares other mountain ranges corresponding in strike and structure the data signed to its upheaval is after the unphosiliferous graywack or cambrian strata and before the cillurian but sir r.i mercheson had shown in 1838 in his cillurian system and the british government surveyors since that time in their sections about 1845 that the longmans and other chains of similar composition in north wales are post cillurian in all of them fossiliferous beds of the lower cillurian formation or landalo flags are highly inclined and often vertical in one limited region the karadoc sandstone a member of the lower cillurian rests unconformably on the denuded edges of the inferior or landalo member of the same group whilst in some cases both of these sets of strata are upturned when therefore so grave an error is detected in regard to the age of a typical chain we are entitled to inquire with surprise by what means nine other parallel chains in France germany and sweden assumed to be anti cillurian have been made to agree precisely in date with the longmans if they are correctly represented as having been all deposited before the deposition of the cillurian strata they cannot be contemporaneous with the longmans and they only prove how little reliance can be placed on parallelism as a test of simultaneousness of upheaval but in truth it is impossible for reasons already given to demonstrate that each of those nine chains coincide in date with one another any more than with the longmans the reader will see in the sequel chapter 31 that mr hopkins has inferred from astronomical calculations that the solid crust of the earth cannot be less than 800 or 1000 miles thick and maybe more even if it be solid to the depth of 100 miles such a thickness would be inconsistent with m e debaumans hypothesis which requires a shell not more than 30 miles thick or even less mr hopkins admits that the exterior of the planet those solid as a whole may contain within it vast lakes or seas of lava if so the gradual fusion of rocks and the expansive power of heat exerted for ages as well as the subsequent contraction of the same during slow refrigeration may perhaps account for the origin of mountain chains for these as dalamu has remarked are far less important proportionally speaking than the inequalities on the surface of an egg shell which to the eye appears smooth a centripetal force affecting the whole planet as it cools seems a mightier cause than is required to produce wrinkles of such insignificant size in pursuing his investigations m e debaumans has of late greatly multiplied the number of successive periods of instantaneous upheaval admitting at the same time that occasionally new lines of upthrow have taken the direction of older ones these admissions render his views much more in harmony with the principles advocated in this work but they impair the practical utility of parallelism considered as a chronological test for no rule is laid down for limiting the interval whether in time or space which may separate two parallel lines of upheaval of different dates among the various propositions above laid down page 164 it will be seen that the sudden rise of the andes is spoken of as a modern event but mr. Darwin has brought together ample data in proof of the local persistency of volcanic action throughout a long succession of geological periods beginning with times antecedent to the deposition of the old litic and cretaceous formations of chili and continued to the historical epic it appears that some of the parallel ridges which compose the cordilleras instead of being contemporaneous were successively and slowly upheaved at widely different epics the whole range after twice subsiding some thousands of feet was brought up again by a slow movement in mass during the era of the eocene tertiary formations after which the whole sank down once more several hundred feet to be again uplifted to its present level by a slow and often interrupted movement in a portion of this latter period the pantheon mud was formed in which the megatherium myladon and other extinct quadrupeds are buried this mud contains in it recent species of shells some of them proper to brackish water and is believed by mr. Darwin to be an estuary or delta deposit ma or bigny however has advanced and hypothesis referred by m e debaumont that the agitation and displacement of the waters of the ocean caused by the elevation of the andes gave rise to a deluge of which this pantheon mud which rises sometimes to the height of 12 000 feet is the result and monument in studying many chains of mountains we find that the strike or line of outcrop of continuous sets of strata and the general direction of the chain may be far from rectilinear curves forming angles of 20 degrees or 30 degrees may be found in the same range as in the alganes just as trains of active volcanoes and the zones throughout which modern earthquakes occur are often linear without running in straight lines nor are all of these though contemporaneous or belonging to our own epic by any means parallel but some at right angles the one to the other slow upheaval and subsidence recent observations have disclosed to us the wonderful fact that not only the west coast of south america but also other large areas some of them several thousand miles in circumference such as scandinavia and certain archipelagos in the pacific are slowly and insensibly rising while other regions such as greenland and parts of the pacific and indian oceans in which atolls or circular coral islands abound are as gradually sinking that all the existing continents and submarine abysses may have originated in movements of this kind continued throughout incalculable periods of time is undeniable and the denudation which the dry land appears everywhere to have suffered favors the idea that it was raised from the deep by a succession of upward movements prolonged throughout indefinite periods for the action of waves and currents on land slowly emerging from the deep affords the only power by which we can conceive so many deep valleys and wide spaces to have been denuded as those which are unquestionably the effects of running water but perhaps it may be said that there is no analogy between the slow upheaval of broad plains or table lands and the matter in which we must presume all mountain chains with their inclined strata to have originated it seems however that the andes have been rising century after century at the rate of several feet while the pampas on the east have been raised only a few inches in the same time crossing from the Atlantic to the pacific in a line passing through Mendoza Mr. Darwin traversed a plain eight hundred miles broad the eastern part of which has emerged from beneath the sea at a very modern period the slope from the Atlantic is at first very gentle then greater until the traveler finds on reaching Mendoza that he has gained almost insensibly a height of four thousand feet the mountainous district then begins suddenly and its breadth from Mendoza to the shores of the pacific is one hundred twenty miles the average height of the principal chain being from fifteen thousand to sixteen thousand feet without including some prominent peaks which ascend much higher now all we require to explain the origin of the principal inequalities of level here described is to imagine first a zone of more violent movement to the west of Mendoza and secondly to the east of that place an upheaving force which died away gradually as it approached the Atlantic in short we are only called upon to conceive that the region of the andes was pushed up four feet in the same period in which the Pampas near Mendoza rose one foot and the plains near the shores of the Atlantic one inch in Europe we have learned that the land at the north Cape ascends about five feet in a century while farther to the south the movements diminish in quantity first to a foot and then at Stockholm to three inches in a century while at other points still farther south there is no movement but in what manner it is asked can we account for the great lateral pressure which has been exerted not only in the andes Alps and other chains but also on the strata of many low and nearly level countries do not the folding and fracture of the beds the anti-clinal and synclinal ridges and troughs as they are called and the vertical and even sometimes the inverted position of the beds imply an abruptness and intensity in the disturbing force wholly different in kind and energy to that which now rends the rocks during ordinary earthquakes i shall treat more fully in the sequel end of chapter 32 of the probable subterranean sources whether of upward or downward movement and of great lateral pressure but it may be well briefly to state in this place that in our own times as for example in chili in 1822 the volcanic force has overcome the resistance and permanently uplifted a country of such vast extent that the weight and volume of the andes must be insignificant in comparison even if we indulge the most moderate conjectures as to the thickness of the earth's crust above the volcanic foci to assume that any set of strata with which we are acquainted are made up of such cohesive and unyielding materials as to be able to resist a power of such stupendous energy if its direction instead of being vertical happen to be oblique or horizontal would be extremely rash but if they could yield to a sideways thrust even in a slight degree they would become squeezed and folded to any amount if subjected for a sufficient number of times to the repeated action of the same force we can scarcely doubt that a massive rock several miles thick was uplifted in chili in 1822 and 1835 and that a much greater volume of solid matter is upheaved wherever the rise of the land is very gradual as in Scandinavia the development of heat being probably in that region at a greater distance from the surface if continents rocked shaken and fissured like the western region of South America are very gently elevated like Norway and Sweden do not acquire in a few days or hours an additional height of several thousand feet this can arise from no lack of mechanical force in the subterranean moving cause but simply because the antagonist power or the strength toughness and density of the earth's crust is insufficient to resist so long as to allow the volcanic energy and indefinite time to accumulate instead of the explosive charge augmenting in quantity for countless ages it finds relief continuously or by a succession of shocks of moderate violence so as never to burst or blow up the covering of incumbent rock in one grand paroxymal convulsion even in its most energetic efforts it displays an intermittent and mitigated intensity being never permitted to lay a whole continent in ruins hence the numerous eruptions of lava from the same vent or chain events and the recurrence of similar earthquakes for thousands of years along certain areas or zones of country hence the numerous monuments of the successive ejection and injection of melted matter in ancient geological epics and the fissures formed in distinct ages and often widened and filled at different eras among the causes of lateral pressure the expansion by heat of large masses of solid stone intervening between others which have a different degree of expensibility or which happen not to have their temperature raised at the same time may play an important part but as we know that rocks have so often sunk down thousands of feet below their original level we can hardly doubt that much of the bending of pliant strata and the packing of the same into smaller spaces has frequently been occasioned by subsidence whether the failure of support be produced by the melting of porous rocks which when fluid and subjected to great pressure may occupy less room than before or which by passing from a pasty to a crystalline condition may as in the case of granite according to the experiments of Deville suffer a contraction of 10 percent or whether the sinking be due to the subtraction of lava driven elsewhere to some volcanic orifice and they're forced outwards or whether it be brought on by the shrinking of solid and stony masses during refrigeration or by the condensation of gases or any other imaginable cause we have no reason to incline to the idea that the consequent geological changes are brought about so suddenly as that large parts of continents are swallowed up at once in unfathomable subterranean abysses if cavities be formed they will be enlarged gradually and as gradually filled we read indeed accounts of engulfed cities and areas of limited extent which have sunk down many yards at once but we have as yet no authentic records of the sudden disappearance of mountains or the submergence or emergence of great islands on the other hand the creeps in coal mines demonstrate that gravitation begins to act as soon as a moderate quantity of material is removed even at a great depth the roof sinks in or the floor of the mine rises and the bent strata often assume as regularly a curved and crumpled arrangement as that observed on a grander scale in mountain chains the absence indeed of chaotic disorder and the regularity of the applications in geological formations of high antiquity although not infrequently adduced to prove the unity and instantaneousness of the disturbing force might with far greater propriety be brought forward as an argument in favor of the successive application of some irresistible but moderated force such as that which can elevate or depress a continent in conclusion I may observe that one of the soundest objections to the theory of the sudden up throw or down throw of mountain chains is this that it provides us with too much force of one kind namely that of subterranean movement while it deprives us of another kind of mechanical force namely that exerted by the waves and currents of the ocean which the geologist requires for the denudation of land during its slow upheaval or depression it may be safely affirmed that the quantity of igneous and alqueous action of volcanic eruption and denudation of subterranean movement and sedimentary deposition not only of past ages but of one geological epic or even the fraction of an epic has exceeded immeasurably all the fluctuations of the inorganic world which have been witnessed by man but we have still to inquire whether the time to which each chapter or page or paragraph of the earth's autobiography relates was not equally immense when contrasted with a brief era of three thousand or five thousand years the real point on which the whole controversy turns is the relative amount of work done by mechanical force in given quantities of time past and present before we can determine the relative intensity of the force employed we must have some fixed standard by which to measure the time extended in its development at two distinct periods it is not the magnitude of the effects however gigantic their proportions which can inform us in the slightest degree whether the operation was sudden or gradual insensible or paroxymal it must be shown that a slow process could never in any series of ages give rise to the same results the advocate of paroxymal energy might assume a uniform and fixed rate of variation in times past and present for the animate world that is to say for the dying out and coming in of species and then endeavor to prove that the changes of the inanimate world have not gone on in a corresponding ratio but the adoption of such a standard of comparison would lead I suspect to a theory by no means favorable to the pristine intensity of natural causes that the present state of the organic world is not stationary can be fairly inferred from the fact that some species are known to have become extinct in the course even of the last three centuries and that the exterminating causes always in activity both on the land and in the waters are very numerous also because man himself is an extremely modern creation and we may therefore reasonably suppose that some of the mammalia now contemporary with man as well as a variety of species of inferior classes may have been recently introduced into the earth to supply the places of plants and animals which have from time to time disappeared but granting that some such secular variation in the zoological and botanical worlds is going on and is by no means holy and appreciable to the naturalist still it is certainly far less manifest than the revolution always in progress in the inorganic world every year some volcanic eruptions take place and a rude estimate might be made of the number of cubic feet of lava and scoria poured out or cast out of various craters the amount of mud and sand deposited in deltas and the advance of new land upon the sea or the annual retreat of wasting sea cliffs are changes the minimum amount of which might be roughly estimated the quantity of land raised above or depressed below the level of the sea might also be computed and the change arising from such movements in a century might be conjectured suppose the average rise of the land in some parts of scandinavia to be as much as five feet in a hundred years the present sea coast might be uplifted 700 feet in 14 000 years but we should have no reason to anticipate from any zoological data hitherto acquired that the moluscus fauna of the northern seas would in that lapse of years undergo any sensible amount of variation we discover sea beaches in norway 700 feet high in which the shells are identical with those now inhabiting the german ocean for the rise of land in scandinavia however insensible to the inhabitants has evidently been rapid when compared to the rate of contemporaneous change in the testaceous fauna of the german ocean were we to wait therefore until the molusca shall have undergone as much fluctuation as they underwent between the period of the lias and the upper olite formations or between the olite and chock nay even between any two of eight subdivisions of the eocene series what stupendous revolutions in physical geography ought we not to expect and how many mountain chains might not be produced by the repetition of shocks of moderate violence or by movements not even perceptible by man or if we turn from the molusca to the vegetable kingdom and ask the botanist how many earthquakes and volcanic eruptions might be expected and how much the relative level of land and sea might be altered or how far the principal deltas will encroach upon the ocean or the sea cliffs recede from the present shores before the species of european forest trees will die out he would reply that such alterations in the inanimate world might be multiplied indefinitely before he should have reason to anticipate by reference to any known data that the existing species of trees in our forests would disappear and give place to others in a word the movement of the inorganic world is obvious and palpable and might be likened to the minute hand of a clock the progress of which can be seen and heard whereas the fluctuations of the living creation are nearly invisible and resemble the motion of the hour hand of a timepiece it is only by watching it attentively for some time and comparing its relative position after an interval that we can prove the reality of its motion end of chapter 11 part 2