Pagina-afbeeldingen
PDF
ePub

the attached valve must have remained ex- of Western Europe, of flint implements, obposed long enough to allow of the growth of viously worked into shape by human hands, the whole coralline, since corallines do not under circumstances which show conclulive imbedded in mud.

sively that man is a very ancient denizen of The progress of knowledge may one day these regions. enable us to deduce from such facts as these It has been proved that the old populathe maximum rate at which the chalk can tions of Europe, whose existence has been have accumulated, and thus to arrive at the revealed to us in this way, consisted of savminimum duration of the chalk period. ages, such as the Esquimaux are now; that, Suppose that the valve of the Crania, upon in the country which is now France, they which a coralline has fixed itself in the way hunted the reindeer, and were familiar with just described, is so attached to the sea- the ways of the mammoth and the bison. urchin that no part of it is more than an The physical geography of France was in inch above the face upon which the sea- those days different from what it is now — urchin rests. Then, as the coralline could the river Somme, for instance, having cut not have fixed itself if the Crania had been its bed a hundred feet deeper between that covered up with chalk mud, and could not time and this; and it is probable that the have lived had itself been so covered, it fol- climate was more like that of Canada or lows that an inch of chalk mud could not Siberia, than that of Western Europe. have accumulated within the time between The existence of these people is forgotthe death and decay of the soft parts of the ten even in the traditions of the oldest hissea-urchin and the growth of the coralline torical nations. The name and fame of to the full size which it has attained. If them had utterly vanished until a few years the decay of the soft parts of the sea-urchin, back; and the amount of physical change the attachment, growth to maturity, and which has been effected since their day rendecay of the Crania, and the subsequent at- ders it more than probable that, venerable tachment and growth of the coralline, took a as are some of the historical nations, the year (which is a low estimate enough), the workers of the chipped flints of Hoxne or accumulation of the inch of chalk must have of Amiens are to them as they are to us in taken more than a year; and the deposit of point of antiquity. a thousand feet of chalk must consequently But, if we assign to these hoar relics of have taken more than twelve thousand long vanished generations of men the greatyears.

est age that can possibly be claimed for The foundation of all this calculation is, them, they are not older than the drift, or of course, a knowledge of the length of boulder clay, which, in comparison with the time the Crania and the coralline needed to chalk, is but a very juvenile deposit. You attain their full size; and on this head precise need go no further than your own sea-board knowledge is at present wanting. But there for evidence of this fact. At one of the are circumstances which tend to show that most charming spots on the coast of Nornothing like an inch of chalk has accumulated folk, Cromer, you will see the boulder clay during the life of a Crania; and, on any forming a vast mass, which lies upon the probable estimate of the length of that life, chalk, and must consequently have come the chalk period must have had a much into existence after it. Huge boulders of longer duration than that thus roughly as chaļk are, in fact, included in the clay, and signed to it.

have evidently been brought to the position Thus, not only is it certain that the chalk they now occupy by the same agency as is the mud of an ancient sea-bottom, but it that which has planted blocks of syenite is no less certain that the chalk sea existed from Norway side by side with them. during an extremely long period, though we The chalk, then, is certainly older than may not be prepared to give a precise esti- the boulder clay. If you ask how much, I mate of the length of that period in years. will again take you no further than the same The relative duration is clear, though the ab- spot upon your own coasts for evidence. I solute duration may not be definable. The have spoken of the boulder clay and drift as attempt to aflix any precise date to the period resting upon the chalk. This is not strictly at which the chalk sea began or ended its true. Interposed between the chalk and existence is baffled by difficulties of the the drift is a comparably insignificant layer, same kind. But the relative age of the cre- containing vegetable matter. But that taceous epoch may be determined with as layer tells a wonderful history. It is full great ease and certainty as the long dura- of stumps of trees standing as they grew. tion of that epoch.

Fir-trees are there with their cones, and You will have heard of the interesting hazel-bushes with their nuts; there stand discoveries recently made, in various parts the stools of oak and yew trees, beeches and alders. Hence this stratum is appro-ther of men, that the chalk is vastly older priately called the forest-bed."

than Adam himself. It is obvious that the chalk must have The Book of Genesis informs us that been upheaved and converted into dry land Adam, immediately upon his creation, and before the timber trees could grow upon it. before the appearance of Eve, was placed As the bolls of some of these trees are from in the Garden of Eden. The problem of two to three feet in diameter, it is no less the geographical position of Eden has greatclear that the dry land thus formed re-ly vexed the spirits of the learned in such mained in the same condition for long ages. matters, but there is one point respecting And not only do the remains of stately oaks which, so far as I know, no commentator and well-grown firs testify to the duration has ever raised a doubt. This is, that of of this condition of things, but additional the four rivers which are said to run out of evidence to the same effect is afforded by it, Euphrates and Hiddekel are identical the abundant remains of elephants, rhinoce- with the rivers now known by the names roses, hippopotamuses, and other great wild of Euphrates and Tigris. beasts, which it has yielded to the zealous But the whole country in which these search of such men as the Rev. Mr. Gunn. mighty rivers take their origin, and through

When you look at such a collection as he which they run, is composed of rocks which has formed, and bethink you that these ele- are either of the same age as the chalk, or phantine bones did veritably carry their of later date. So that the chalk must not owners about, and these great grinders only have been formed, but after its formacrunch in the dark woods of which the for- tion the time required for the deposit of est-bed is now the only trace, it is impossi- these later rocks and for their upheaval into ble not to feel that they are as good evi- dry land must have elapsed, before the dences of the lapse of time as the annual smallest brook which feeds the swift stream rings of the tree-stumps.

of “the great river, the river of Babylon," Thus there is a writing upon the wall of began to flow. cliffs at Cromer, and whoso runs may read it. It tells us, with an authority which can- Thus evidence which cannot be rebutted, not be impeached, that the ancient sea-bed and which need not be strengthened, though of the chalk sea was raised up and remained if time permitted I might indefinitely indry land until it was covered with forest, crease its quantity, compels you to believe stocked with the great game whose spoils that the earth, from the time of the chalk to have rejoiced your geologists. How long the present day, has been the theatre of a it remained in that condition cannot be said; series of changes as vast in their amount as but the whirligig of time brought its re- they were slow in their progress. The area venges " in those days as in these. That on which we stand has been first sea and dry land, with the bones and teeth of gen- then land for at least four alternations, and erations of long-lived elephants hidden has remained in each of these conditions away among the gnarled roots and dry for a period of great length. leaves of its ancient trees, sank gradually Nor have these wonderful metamorphoses to the bottom of the icy sea, which covered of sea into land, and of land into sea, been it with huge masses of drift and boulder confined to one corner of England. Durclay. Sea-beasts, such as the walrus, now ing the chalk period, or cretaceous epoch, restricted to the extreme north, paddled not one of the present great physical feaabout where birds had twittered among the tures of the globe was in existence. Our topmost twigs of the fir-trees. How long great mountain ranges, Pyrenees, Alps, this state of things endured we know not, Himalayas, Andes, have all been upheaved but at length it came to an end. The up- since the chalk was deposited, and the creheaved glacial mud hardened into the soil taceous sea flowed over the sites of Sinai of modern Norfolk. Forests grew once and Ararat. more, the wolf and the beaver replaced the All this is certain, because rocks of crereindeer and the elephant; and at length taceous or still later date have shared in the what we call the history of England dawned. elevatory movements which gave rise to

Thus you have, within the limits of your these mountain chains, and may be found own county, proof that the chalk can justly perched up, in some cases, many thousand claim a very much greater antiquity than feet high upon their flanks. And evidence even the oldest physical traces of mankind. of equal cogency demonstrates that, though But we may go further, and demonstrate, in Norfolk the forest-bed rests directly upon by evidence of the same authority as that the chalk, yet it does so, not because the which testifies to the existence of the fa- | period at which the forest grew immediately

66

followed that at which the chalk was formed, And it is by the population of the chalk but because an immense lapse of time, rep- sea that the ancient and the modern inhabresented elsewhere by thousands of feet of itants of the world are most completely conrock, is not indicated at Cromer.

nected. The groups which are dying out I must ask you to believe that there is no flourish side by side with the groups which less conclusive proof that a still more pro- are now the dominant forms of life. longed succession of similar changes oc

Thus the chalk contains remains of those curred before the chalk was deposited. strange flying and swimming reptiles, the Nor have we any reason to think that the pterodactyl, the ichthyosaurus, and the plefirst term in the series of these changes is siosaurus, which are found in no later deknown. The oldest sea-beds preserved to posits, but abounded in preceding ages. us are sands, and mud, and pebbles, the The chambered shells called ammonites and wear and tear of rocks which were formed belemnites, which are so characteristic of in still older oceans.

the period preceding the cretaceous, in like But, great as is the magnitude of these manner die. with it. physical changes of the world, they have But amongst these fading remainders of been accompanied by a no less striking a previous state of things are some very series of modifications in its living inhab- modern forms of life, looking like Yankee itants.

pedlars among a tribe of Red Indians. All the great classes of animals, beasts Crocodiles of modern type appear; bony of the field, fowls of the air, creeping things, fishes, many of them very similar to existand things which dwell in the waters, flour- ing species, almost supplant the forms of ished upon the globe long ages before the fish which predominate in more ancient seas; chalk was deposited. Very few however, and many kinds of living shell-fish first beif any, of these ancient forms of animal life came known to us in the chalk. The vegewere identical with those which now live. tation acquires a modern aspect. A few Certainly, not one of the higher animals living animals are not even distinguishable was of the „same species as any of those as species from those which existed at that now in existence. The beasts of the field remote epoch. The Globigerina of the in the days before the chalk were not our present day, for example, is not different beasts of the field, nor the fowls of the air specifically from that of the chalk; and the such as those which the eye of man has same may be said of many other Foramiseen flying, unless his antiquity dates in- niferæ. I think it probable that critical and finitely further back than we at present sur- unprejudiced examination will show that mise. If we could be carried back into more than one species of much higher anithose times, we should be as one suddenly mals have had a similar longevity, but the set down in Australia before it was colo- only example which I can at present give nized. We should see mammals, birds, confidently is the snake's-head lamp-shell reptiles, fishes, insects, snails, and the like, (Terebratulina caput serpentis), which lives clearly recognisable as such, and yet not in our English seas and abounded (as Tereone of them would be just the same as those bratulina striata of authors) in the chalk. with which we are familiar, and many would The longest line of human ancestry must be extremely different.

hide its diminished head before the pedigree From that time to the present, the popu- of this insignificant shell-fish. We Englishlation of the world has undergone slow and men are proud to have an ancestor who was gradual but incessant changes. There has present at the Battle of Hastings. The anbeen no grand catastrophe - no destroyer cestors of Terebratulina caput serpentis may has swept away the forms of life of one have been present at a battle of Ichthyosauperiod, and replaced them by a totally new riæ in that part of the sea which, when the creation; but one species has vanished and chalk was forming, flowed over the site of another has taken its place; creatures of Hastings. While all around has changed, one type of structure have diminished, those this Terebratulina has peacefully propagated of another have increased, as time has its species from generation to generation, passed on. And thus, while the differences and stands to this day, as a living testimony between the living creatures of the time to the continuity of the present with the before the chalk and those of the present past history of the globe. day appear startling, if placed side by side, we are led from one to the other by the Up to this moment I have stated, so far most gradual progress, if we follow the as I know, nothing but well-authenticated course of Nature through the whole series facts, and the immediate conclusions which of those relics of her operations which she they force upon the mind. has left behind.

But the mind is so constituted that it

does not willingly rest in facts and immedi- | lar species may have lived on from epoch ate causes, but seeks always after a knowl- to.epoch.) Thus each epoch has had its edge of the remoter links in the chain of peculiar crocodiles, though all since the causation.

chalk have belonged to the modern type, Taking the many changes of any given and differ simply in their proportions, and spot of the earth's surface, from sea to land in such structural particulars as are discernand from land to sea, as an established fact, ible only to trained eyes. we cannot refrain from asking ourselves How is the existence of this long succeshow these changes have occurred. And sion of different species of crocodile to be when we have explained them — as they accounted for? must be explained — by the alternate slow Only two suppositions seem to be open movements of elevation and depression to us – Either each species of crocodile has which have affected the crust of the earth, been specially created, or it has arisen out we go still further back, and ask, Why of some pre-existing form by the operation these movements ?

of natural causes. I am not certain that any one can give Choose your hypothesis ; I have chosen you a satisfactory answer to that question. mine. I can find no warranty for believing Assuredly I cannot. All that can be said in the distinct creation of a score of succesfor certain is, that such movements are sive species of crocodiles in the course of part of the ordinary course of nature, inas- countless ages of tine. Science gives no much as they are going on at the present countenance to such a wild fancy; nor can time. Direct proof may be given that some even the perverse ingenuity of a commentaparts of the land of the northern hemisphere tor pretend to discover this sense in the are at this moment insensibly rising and simple words in which the writer of Geneothers insensibly sinking; and there is indi-sis records the proceedings of the fifth and rect but perfectly satisfactory proof, that an sixth days of the Creation. enormous area now covered by the Pacific On the other hand, I see no good reason has been deepened thousands of feet since for doubting the necessary alternative, that the present inhabitants of that sea came all these varied species have been evolved into existence.

from pre-existing crocodilian forms by the Thus there is not a shadow of a reason operation of causes as completely a part of for believing that the physical changes of the common order of nature as those which the globe in past times have been effected have effected the changes of the inorganic by other than natural causes.

world. Is there any more reason for believing that Few will venture to affirm that the reasonthe concomitant modifications in the forms of ing which applies to crocodiles loses its the living inhabitants of the globe have been force among other animals, or among plants. brought about in other ways?

If one series of species has come into exBefore attempting to answer this ques- istence by the operation of natural causes, tion, let us try to form a distinct mental it seems folly to deny that all may have picture of what has happened in some spe- arisen in the same way.

The crocodiles are animals which, as a A small beginning has led us to a great group, have a very vast antiquity. They ending: If I were to put the bit of chalk abounded ages before the chalk was depos- with which we started into the hot but obited; they throng the rivers in warm cli- scure flame of burning hydrogen, it would mates at the present day. There is a dif- presently shine like the sun. It seems to ference in the form of the joints of the back- me that this physical metamorphosis is no bone, and in some minor particulars, between false image of what has been the result of the crocodile of the present epoch, and those our subjecting it to a jet of fervent though which lived before the chalk; but, in the nowise brilliant thought to-night. It has cretaceous epoch, as I have already men- become luminous, and its clear rays, penetioned, the crocodiles had assumed the mod- trating the abyss of the remote past, have ern type of structure. Notwithstanding brought within our ken some stages of the this, the crocodiles of the chalk are not evolution of the earth. And in the shifting identically the same as those which ved in “ without haste, but without rest” of the the times called “older tertiary,” which land and sea, as in the endless variation of succeeded the cretaceous epoch; and the the forms assumed by living beings, we have crocodiles of the older tertiaries are not observed nothing but the natural product identical with those of the newer tertiaries, of the forces originally possessed by the nor are these identical with existing forms. substance of the universe. (I leave open the question whether particu

cial case.

our

From Fraser's Magazine. most perfect specimens of each race and ON THE FAILURE OF NATURAL SELEC- tribe, the strongest, the swiftest, the health

TION' IN THE CASE OF MAN. iest, the most courageous — those fullest EVERY one now is familiar with the Dar

of vitality - live longest, feed best, overwinian theory of the origin of species, at least mates; and, in virtue of these advantages,

come their competitors in the choice of in its main principles and outlines: and

become nearly all men qualified to form an opinion

as it is desirable they should be

The are convinced of its substantial truth. That

the progenitors of the future race. theory explains how races of animals vary weak, are slain or drop out of existence;

poorer specimens, the sick, the faulty, the as ages roll on, so as to adapt themselves to

are distanced in the chase, are beaten in the the changing external conditions which those fight, can find no females to match with ages bring about. At every given moment, them; and the species is propagated and in every given spot on the earth's surface, continued mainly, increasingly, if not ex; a “struggle for existence is going on among clusively, from its finest and most selected all the forms of organic life, animal and veg- individuals — in a word, its élite. etable, then and there alive; a struggle in

This explains not only those extraordiwhich, as there is not room for all, the weaker and less adapted succumb, while the nary changes in the form and habits of the

same animals which, when aided and aggrastronger and better adapted survive and

vated by man's requirements and careful multiply. As surrounding circumstances, climatic or geological, vary and are modi- ticated races, but also those purely natural

management, strike us so forcibly in domesfied, corresponding variations (such as are always incidentally appearing among the off though far slower modifications which geospring of all creatures) in the inhabitants knowledge. Mr. Wallace, in the admirable

logical researches have brought to of each district crop up, increase, spread, and become permanent. The creatures that model of succinct stateinent and lucid rea

paper quoted below — which is a perfect are most in harmony with surrounding circumstances have a manifest daily and hourly up the heat of the system. Our supposed perfect advantage over those which are less in bar- animal is no longer in harmony with its universe; mony: live when they die; flourish when it is in danger of dying of cold or of starvation. But they fade; endure through what kills others; swifter than others –

the animal varies in its ofispring. Some of these are

they still manage to catch can find food, catch prey, escape enemies, food enough; some are hardier and more thickly when their feebler, slower, blinder breth- furred--they manage in the cold nights to keep ren are starved and slain. * Thus the clad soon die off. Again and again, in each suc

ceeding generation, the same thing takes place. By *. The grand feature in the multiplication of or- this natural process, which is so inevitable that it ganic life is that of close general resemblance, com cannot be conceived not to act, those best adapted bined with more or less individual variation. The to live, live ; those least adapted, die. It is somechild resembles its parents or ancestors more or less times said that we have no direct evidence of the closely in all its peculiarities, deformities, or beau- action of this selecting power in nature. But it ties; it resembles them in general more than it does seems to me we have better evidence than even diany other individuals; yet children of the same pa- rect observation would be, because it is more unirents are not all alike, and it often happens that versal, viz. the evidence of necessity. It must be they ditler very considerably from their parents and so; for, as all wild animals increase in a geometrifrom each other. This is equally true of man, of all cal ratio, while their actual numbers remain on the animals, and of all plants. Moreover, it is found average stationary, it follows that as many die anthat individuals do not differ from their parents in nually as are born. If, therefore, we deny natural secertain particulars only, while in all others they are lection, it can only be by asserting that in such a exact duplicates of them. They differ from them case as I have supposed the strong, the healthy, the and from each other in every particular: in form, swift, the well clad, the well organised animals in in size, in colour, in the structure of internal as well every respect, have no advantage over, as of external organs ; in those subtle peculiarities the average live longer than, the weak, the unwhich produce differences of constitution, as well healthy, the slow, the ill clad, and the imperfectly as in those still more subtle ones which lead to mod organised individuals ; and this no sane man has ifications of mind and character. In other words, 1 yet been found hardy enough to assert. in every possible way, in every organ and in every not all ; for the offspring on the average resemble function, individuals of the same stock vary. their parents, and the selected portion of each suc

Now, health, strength, and long life are the re- ceeding generation will therefore be stronger, sults of a harmony between the individual and the swifter, and more thickly furred than the last ; and universe that surrounds it. Let us suppose that at if this process goes on for thousands of generations, any given moment this harmony is perfect. A cer- our animal will have again become thoroughly in tain animal is exactly fitted to secure its prey, to harmony with the new conditions in which he is escape from its enemies, to resist the inclemencies placed. But he will now be a different creature. He of the seasons, and to rear a numerous and healthy will be not only swifter and stronger, and more offspring. But a change now takes place. A series furry; he will also probably have changed in col. of cold winters, for instance, come on, making food our, in form, perhaps have acquired a longer tail, scarce, and bringing an immigration of some other or differently shaped ears ; for it is an ascertained animals to compete with the former inhabitants of fact, that when one part of an animal is modified, the district. The new immigrant is swift of foot some other parts almost always change as it werein and surpasses its rivals in the pursuit of game ; the sympathy with it.'- Wallace On the Origin of winter nights are colder, and require a thicker fur Human Races.' Journal of the Anthropological Soas a protection, and more nourishing food to keep I ciety, No. 5.

do not on

But this is

ܪ

« VorigeDoorgaan »