Изображения страниц
PDF
EPUB

and subsidence is passing from the scientific mind. It too is doomed.

The latest ideas of upheaval and subsidence entertained in what may be called “head-quarters” in this science, are stated by Professor Ramsay, in his address already quoted. He says, “There, in the Alps, we find areas half as large as an English county, in which a whole series of formations has been turned upside down. But by what means were masses of strata many thousands of feet thick bent and contorted, and raised into the air, so as to produce such results, and thus affording matter for the elements towork upon? Not byigneous or other pressure and upheaval from below; for that would stretch instead of crumpling the strata in the manner in which we find them, in great mountain chains like the Alps, or in less disturbed groups like those of the Highlands, Wales, and Cumberland, which are only fragments of older mountain-ranges; but perhaps, as some have supposed, from the radiation from the earth of heat into space, producing gradually a marked shrinkage of the earth's hardened crust.”* Again, he speaks of the formation of mountainchains by“ direct igneous action operating from below,” as an old-fashioned idea which he wonders to see produced in memoirs of even well-informed writers now, and thus he leads on to the new theory of a “shrinkage of the earth's hardened crust." He does not say how this shrinkage and crumpling were produced. He only speaks of the radiation of heat as that which "some have supposed;' and in regard to the formation of gneiss and granite, he says frankly, as to how they were produced, he'“ cannot tell;" only he imagines that somehow the means must have been heat! This launches the hypothesis of a shrinking crust on the sea of willing speculation; but by “the law of continuity,” which has so ruled the race of theories from the beginning till now, ought we not to expect that shrinkagewill, perhaps, by the time the British Association meets again, have given place to a successor ? Surely when we recollect that the lowest stratum yet discovered in the formation of the globe is one from water, which gives no sign whatever of shrinkage, it requires a very bold stroke of fancy to imagine that such a thing is to account for the mighty disturbance evident even in the Alps themselves. Who, then, can contemplate the real state of speculative geology, as we are thus finding it in its very foundations, without seeing that its great leaders are completely adrift, and that without either chart or compass by which to steer ? We have been kindly told, not to be afraid of the effect which this science may have

* Geological Magazine for November 1st, 1866, p. 510.

on religion. We hope it is understood that our fear has never arisen from its truthfulness. But false speculations are to be feared.

It may be the highest presumption in us to allow the thought to enter our minds, yet we cannot help thinking that the bewilderment of our geological guides may be in a great measure traced to one fallacy. They seem to think that it is impossible that a stratum of rock could have been formed anywhere else on the earth's surface than where it now lies. Although we have seen that a whole formation, half as large as an English county, has been turned literally upside down, it seems, ac. cording to current ideas, that this remarkable revolution must have taken place on the spot above which the strata of this formation were originally deposited. Upheaval and subsidence being the only recognized movements of the earth's surface, the transportation of such masses from one latitude or longitude to another, is not to be thought of! It is, however, extremely difficult for one who looks at the subject from a common-sense point of view, to imagine the mass of rock forming half an English county turned over, so that it would lie upside down over the same portion of terrestrial surface on which it lay before ; but if such a mass might change its place, so that its latitude or longitude, or both, should no longer be the same as they were, it is hard to see how the British Isles themselves might not also change their place. But such change of place at once introduces the idea of a change of climate, and that again a change of the plants and animals inhabiting the transported region. Alterations of climate have been generally accounted for by referring to changes in the atmosphere arising from new directions of the oceanic currents, or changes of sea into land, or of land into sea. But such changes could never account adequately for the plants and animals of a tropical climate that are found embedded in the rocks even of England itself. Winds passing over burning deserts, and the Gulf Stream passing more directly northward, might modify the climate greatly; but with the relation of the sun and surface, as it stands, they could never account for the fossils that are found in the North now. The case is very different with the view to which I am now calling attention. For example, when we have satisfactory evidence that a climate like that of Egypt once affected the life of England, and that a change from Egyptian heat to our present climate has extinguished certain species that now live only in the Nile, or in rivers of distant lands, we are free to ask whether this change is the result of an alteration in the atmosphere of England, considered in its relation to the terrestrial surface only, or of an altered position of England in relation to the sun. I am aware that I am suggesting a “heresy” for which Mr. Evan Hopkins is responsible now for some twenty years; but surely the fact that an idea has been condemned as “heretical” can be no drawback to it among truly scientific men.* The idea is forced upon us, not by the weight of any name, unless it be that of Professor Ramsay. His facts and his bewilderment, when meditating among those old Alps, seem to urge us to accept the idea. His observed crumpling cannot be explained by his suggested shrinkageof that we are sure. It can be explained by a lateral motion of the earth's unequal surface-of that we are as sure. How could shrinkage lay half an English county flat on its back? A force sufliciently powerful, pushing the mass along among other masses, might accomplish such an overturn. That force whose shiverings shake the solid globe at once over even 1,500 miles, when at its steady, earnest work, is more than enough to lay England itself, if not upside down, at least on a new and distant bed in the course of years. We do not say that this view is infallibly right, nor can we say that it is wrong; but we certainly think that the progress of Descriptive Geology shuts us up to some doctrine of lateral movement in the surface of the globe, if we would allow our physical principles to keep pace with discovery. Its rejection by geologists, combined with the necessity for some such explanatory force, is another powerful proof that the science we have in hand is loose in an extreme degree in its fundamental principles. As it now stands, no one can say what its doctrine as to the real character of strata, or as to their superposition, may be tomorrow. It is, in these essential principles, in a state of perfect indecision, and ready, like a vane in the wind, to turn itself to any current that

may

blow.

But it is equally clear that a thoroughly unsettled state of mind prevails among speculative geologists as to organic remains. We have already seen how important are the discoveries that men have thought they had made in this direction. Sir Roderick Murchison especially lays great stress on the idea of successive creations in the peopling of the globe, and those who take very different views from his are almost equally interested in progression. It is clear, however, that discovery of great importance is threatening the science in the direction of its doctrine as to these organic remains. The writer of the

* See Geology and Terrestrial Magnetism, by Evan Hopkins, C.E., F.G.S. third edition, 1865 ; a book worthy of earnest study.

first article in the Geological Magazine for 1865, from which I have already quoted, in asking the question,

“ Have we got back to the first of earth's created beings?” and replying " That is not for us to say,” concludes his remarks with these words : “ Judging from analogy, then, the Eozoön rock of Canada was the foraminiferous formation in one part of an ocean which elsewhere may have borne manifold and higher species, and buried them in sands and muds, that have since lost all form and feature by the metamorphism of age and pressure, or which were altogether shorn away by wave and weather when the old ocean-bed was lifted up."* Nothing can be more evident than that language such as this expresses bewilderment in fundamental thought, such as prepares men for any change. The theory of progression, as it has been called, is sick and ready to die. That is, not merely Darwin's notion of the transmutation of species, but the theory of a gradual evolution of higher forms, either by creations or transmutations. The grand, general idea, that the production of man formed the last step in an inconceivably long chain of development, which rose from a low first link fastened on somewhere to a piece of “fundamental granite,” is expiring! If “manifold and higher species” might live in the ocean at the time of the Eozoon, why might not manifold and higher species live also on land? And if higher species, why not the highest ? Here we ask our guide, if he knows the road beyond? and he replies, “No, gentlemen, we are off the track. I see no path either behind or ahead!” Such is Geological Science in one of its grandest features at the present hour. Pressed to speak as to even the way to light, it can tell us simply nothing. So we must think for ourselves.

[ocr errors]
[ocr errors]

If, then, we give up the merely vertical movement of upheaval and subsidence, with latitude maintained, and believe that since half an English county could be turned over like a turf on its grassy side, any number of such formations could be pushed along from tropical to temperate and thence to arctic positions on the great globe, we have, at least, one line of thought marked off, by which changes of climate, and all consequent changes of species, may ultimately be accounted for. We have also that in view, of which the sickly theory of progression, as it has been held by geologists, may be allowed to die, and the doctrine of creation, as taught us through Moses, may be seen in its proper scientific light.

As a fuller illustration of what we mean, we must direct

* Geological Magazine, January, 1865, p. 3.

رو

the most earnest attention to some of the very thoroughly ascertained facts of geology. We observe that Sir Charles Lyell says: Mr. (now Dr.] Bowerbank, in a valuable publication on the fossil fruits and seeds of the island of Sheppey, near London, has described no less than thirteen fruits of palms of the recent type Nipa, now only found in the Molucca and Philippine Islands, and in Bengal.” He says also, that "the teeth and bones of crocodiles and turtles are found here, with other relics of an unquestionably tropical character. Here then fairly occurs the question as to whether all these undoubtedly tropical productions and living creatures grew in the present latitude of London ; or have the relics of a truly tropical situation been transported northward by the removal of the strata in which they were entombed ? Certain minor causes might, perhaps, account adequately for a milder climate prevailing in England, or in its latitude, than even that which is produced by the Gulf-stream now. But it is impossible, apart from the vertical rays of a tropical sun, to account for the richest results of a tropical clime ; and the very richest are entombed in the London clay. Is it not evident that this clay was formed within the tropics, and that somehow it has been removed, until it lies in our northern latitude ? And is it not this removal alone that can account for the difference between its climatal character and that of the beds of sediment now forming in the Thames ? But if such is the account to be given of changes in climate, we must recast our ideas of the extinction of species, and alter our views of what is called geological time. The shutting off of the warm waters of the great Atlantic current from our shores might bring a glacial period over Britain; but as we know, the letting on of those waters would not give us the heat of Bengal. No raising or sinking of the surface, which could be conceived, could give us the effects of the direct radiance of a tropical sun without those rays themselves. But the removal of

But the removal of the abodes of tropical creatures from under tropical skies is abundantly sufficient to account for their extinction or emigration from the portion of the earth's surface so removed; and it requires only, that we should be able to form some true idea of the time consumed in this removal, in order to our coming somewhat near the date of the extinctions and emigrations which the records of the rocks disclose.

It is at this point that we are, as it were, compelled to look into current astronomy, where that science has been called in to account for changes on the surface of the earth. And here, too, we must distinguish between practical and physical science. Because astronomers predict, to the fraction of a

« ПредыдущаяПродолжить »