Thursday, 26 March 2015

GEIKIE ON " GEOLOGICAL TIME."

Mr. Geikie, who was, received with applause, commenced his lecture as follows:—

"Among the causes which have retarded and even yet retard, the progress of geology, none have exercised a more pernicious influence than the popular misconceptions and prejudices regarding the past history of our planet.  Though the idea that the world is only some 5000 years old has been abandoned even by theological writers of the most orthodox school, the influence of that widespread belief has by no means passed away. Nor need this be in any degree a matter of surprise; for, apart from the effect of all traditional teaching on the subject it is but natural to contemplate the earth in its unity, as the result of one creative act, rather than as the harmonious issue of many varied and long-continued  processes. Varieties of outline in mountain and valley, hill and plain, and even sometimes the corresponding diversities in the nature of the rooks underneath, form the subject of familiar remark ; but they do not naturally suggest the vastness of the earth's contiguity—still less, the widely different ages of contiguous parts of the earth's surface.  These are ideas which it requires more than a cursory observation to master. Nor until after long and patient study do we come in some measure to realise the wonderfully complex character of the crust of our globe, and the immensity of the periods which it records. So long as we labour under false conceptions in this matter, our advance in geology can be neither rapid nor sure. When, therefore the Council of your Society, a short while ago, asked me to address you on some geological subject, it occurred to me that perhaps no topic would be more likely at once to interest you and to offer suggestions that might be helpful in the practical pursuit of geological studies.
 I propose this evening to speak to you, of geological time ; not with the view of saying anything new, or of laying before you more than a mere outline of a portion of this great question, but with the wish to press very earnestly upon your attention certain principles which cannot be too  vividly or too constantly remembered. To many men unacquainted with the methods of geological research, there doubtless, appears to be much that is conjectural, if not incredible, in the statements of geologists as to the different relative ages of various portions of the earth's crust. The apparent confidence with which one mountain is pronounced to be older than another wakens in their mind first a feeling of wonder which in the end not improbably shades into one of vague doubt. And when they hear it asserted not merely that the hills differ from each other in age, but that, one part of a hill may be of widely different antiquity from the rest of it, and even that the base of a mountain may sometimes be greatly younger than the top, their incredulity is apt to grow, into strong disbelief. It was under the influence of such convictions that Cowper penned his contemptuous notice of the geologists of his time. And notwithstanding the amazing progress of science since his day, and the wide spread of knowledge through all classes of society, the old popular prejudices on this subject, though soundly shaken, are very far from being removed. People admit in words the deductions of science, and yet, partly from the strength of early association, and partly from the irksomeness of mastering the methods by which these deductions are reached, they are frequently found to think and argue with their old prejudices in full force.
     My main object this evening is to narrate, as clearly and briefly as I can, the nature of the evidence which is thus ignored, and to indicate, by examples more or less familiar to all, the manner, in which that evidence is brought to bear upon the question of geological time. At the outset we are met with certain preliminary objections. It is alleged that the past history of the planet has beet one of convulsion and cataclysm ; that the present order of nature is the quiescent result of much turmoil ; that the energy of the universe having been decreasing all geological operations must have been carried on upon a greater scale than now — and hence that no safe generalisation can be drawn from the existing economy of nature to those who have preceded it. Into some of those questions it would be wholly out of place to enter this evening. I choose a line of argument which precludes cataclysms; and in which we have to deal with phenomena where the lapse of time can be relatively measured. With regard to what are called uniformitarian views in geology, though it is quite possible that in some respects they may have been carried too far, yet I believe that a thoughtful survey of the geological records, more especially with reference to the history of life, and the relation between life and the physical revolutions of the earth's surface, leads naturally and irresistibly to the conclusion that though the geological agencies may have varied in their energy in past time, nevertheless there is no evidence to indicate that, on the whole, they have materially differed from their present rate during the periods of which geology interprets the memorials. It is safer therefore, to proceed on a basis of ascertained fact and experience than upon what at best might be only plausible speculation.
By such a course there is found to be an admirable harmony between the world of to-day and the relics of earlier worlds buried in the rocks. The present becomes the true key to the past, while the past in turn explains much that would otherwise be hard to understand in the present." Mr. Geikie then proceeded to speak of the geological evidence of the earth's antiquity under three heads ; 1. "Inorganic evidence ;  Organic evidence ; and The bearing of astronomical and physical data upon the question.
Under the first of these divisions he noticed the fact that the whole surface of the earth from the mountain top to the sea shore was slowly changing and undergoing a  process of waste. The atmosphere acting upon the rocks disintegrated them, and the detritus was then washed down by the rain into the rivers and the sea. If they considered the great circulation of water upon the globe they would find that it made the greatest changes of any of the agents recognised by geology. The process of waste, however was slow; as scarcely to be appreciable in a man's lifetime. Besides the changes effected by water there was the action of icebergs and glaciers, which acted mechanically in grinding the rocks to sand and mud. The lecturer illustrated this portion of his lecture by reference to well drawn pictures of the glacier-fields of Norway, and remarked that in every Scottish glen they found that the rocks had been ground down in the same way as they were being planed away in Norway, and how vast must have been the time taken in the process. Representations of sandstone rocks standing upon the Laurentian gneiss in Sutherland and Ross shires were pointed to as illustrating the gradual manner in which the former had been worn and proving that there had not been any sudden convulsion or cataclysm in producing the geologic changes alluded to.
 Coming to the organic evidence of the changes, the lecturer referred to the occurrence of a Germanic Flora in this country as a proof that the temperature was much more moderate in this country now than it had been in former eras. Plants that formerly bloomed in our valleys had now become alpine in their character and were only to be found on, the tops of the hills. In regard to the Fauna shells that had lived during the glacial period were still to be found in our seas, and only a few species had become extinct. As the plants had become inhabitants of hill tops, so these shells of a former age had become denizens of the deeper parts of the sea. All these changes had been effected since the glacial period, and when they knew, as they did, the length of time that had elapsed since then, how long must have been the time since the plants and animals of former periods were extinguished !
 In regard to the bearing of astronomical and physical data upon the question, Mr. Geikie remarked that the geological record afforded no data for computing the length of its periods in years. If, however, it contained traces of any great cosmical event it might be possible to arrive at the date of such an event, for the astronomical periods were not like those of geology, but could be computed in years. It had long been the belief of many geologists that if any actual data of this kind were to be found, it must be by the labours of the astronomer, rather than of the geologist. An attempt had recently been made by Mr. James Croll, Glasgow, to connect in this way the two sciences, and his paper deserved careful study.  Taking the glacial period as his starting point, Mr Croll proposed to explain the recurrence of cold periods in the earth's history by the combination of the procession of the Equinoxes with the slow secular variations in the eccentricity of the earth's orbit. Reasoning upon this, he demonstrated that the nearest period to which the glacial period could be assigned was about 800,000 years' ago. Comparatively speaking, the change produced on the earth's crust in that time had been very small indeed, and as most of the shells living then were living still, how enormous must have been the time required to extinguish the numerous extinct races. If they thus got a beginning, they might yet be able to form an approximate value for the other periods : but geologists were just groping their way, and what was stated must be taken with caution, as they desired rather to illustrate the truth than state dogmas. (Hear,)
 " In conclusion, if the subject has been placed in a clear light, this evening, it will, I trust, be apparent how vast must be the antiquity of our globe, and how varied, but firm, is the evidence on which the belief in that antiquity rests. There is no doctrine in geology more important than this, and none, perhaps, which it is more difficult duly to appreciate, and acknowledge. It runs counter to old beliefs and prejudices, which as I have said, are apt to show their lingering influence, even after we admit them to be wrong. As geologists, we are apt to err rather by underrating than by overrating the value of time in the past history of the globe. We should lose no opportunity, therefore, of bringing before our minds such facts and just inferences as may tend to quicken our perceptions in this matter. Not that any magic influence is to be attributed to the lapse of time as in itself a geological agent ; but that only with the belief in vastly protracted periods can the changes which are chronicled in the rocks be understood, and the history of the ancient world be brought into harmony with the economy of this world around us. In all such questions as the history of life upon the globe and the antiquity of living species, including, of course, man, the element of time plays so important a part that it must be made itself a subject of study if these questions are to be intelligently discussed. But it is almost vain to hope that this will be often done save by geologists themselves. Hence the deductions of geologists are tacitly accepted by one section of the community, and ridiculed by another.
 The old warfare against our science, after slumbering for a while, has of late years been revived, and seems to be increasing in activity. Within the last few days we have seen two eminent members of the legal faculty enter the lists, and denounce modern science and its tendencies after a fashion which is sufficiently familiar, as used by our old clerical opponents, but which is not common with laymen, and especially with lawyers. (Laughter and applause.) One of these gentlemen tells us that he addresses himself to the subject 'in the mere spirit of a lawyer,' that he has 'no pretensions to scientific knowledge,' that he 'would not presume to contradict Mr. Darwin or Sir Charles Lyell on a matter of science ; he would not even presume to judge of it,' ' But,' he goes on to add, 'I can tell whether the facts which they have proved lead to the result which other people say they lead to; for when they come to that they descend from their eminence into the ordinary arena of hard logic' (A laugh.) Perhaps, like myself, you have amused yourself in endeavouring  to conjecture what this gentleman's conception of science can possibly be. I have always been in the habit of believing that the great aim of science is to establish principles, and that the mere hoarding of facts is a pursuit comparatively worthless, if it does not lead up to the perception of great truths. (Applause.) But this it seems is a mistaken belief. We now learn that the special function of science is to gather facts ; that the persons so engaged are placed on an eminence from which they must descend when they wish to put the facts together, and understand their bearings. A man who protests his ignorance of scientific knowledge, claims to decide upon the results of scientific inquiry. He does 'not presume to judge' or understand the facts, but he has no hesitation in asserting his competence to pronounce what conclusion may or may not be drawn from them, because they are then brought down into 'the ordinary arena of hard logic.' (Applause.) And the 'hard logic' which he uses is found to be only the old argumentum ad hominem, of which, in scientific questions at least it had been hoped that people were now getting ashamed. This speaker said most truly that he had addressed himself to these topics 'in the mere spirit of a lawyer.' Let us hope that, if he returns to them, it will be in another and better spirit (Loud applause.)
 This is only a sample of the kind of opposition which is offered. We are held up as scoffers, sceptics, infidels, and atheists, who do not openly avow their designs but seek insidiously to undermine the religious faith of the country ; we are taunted with the credulity of unbelief, and ridiculed as groping and burrowing philosophers, who say the one day what they unsay the next—men who, rather than believe in Scripture, "with strange credulity accept without evidence theories the most wild, irrational, and incredible"—men whose great aim seems to be to liberate mankind from the thrall of Christianity. I wish it were possible for those who use such language to know how profoundly they are mistaken. (Applause.)
The opinions which, as geologists, we hold regarding such questions as the antiquity of man have not been lightly taken up ; they have been forced upon us, in spite of old convictions, by the irresistible march of discovery, and have been or are now being formed in a manner against our will. If these opinions are sometimes opposed to long-established beliefs, we cannot help it. The truth is not of our making ; we cannot conceal it, and we dare not if we could. (Applause.) I have, indeed, no sympathy with men who obtrude  their obnoxious scientific doctrines when no other result is likely to follow than the irritating of the feelings and the wounding of the consciences of their fellow-men. There is a time to keep silence, and a time to speak out. As little can I sympathise with men who, having often but a slender stock of knowledge, seek to persuade the people that between the findings of science and orthodox biblical teaching there is no discrepancy ; who try to smother up difficulties, and cry peace, peace, when there is no peace. There can be no peace until the attempt is relinquished to crush the spirit of inquiry into an old and narrow mould. Our opponents assure us that they court the fullest investigation, and would give the freest scope for research. But what is the worth of this liberty when in the next breath they proceed to set bounds beyond which it cannot go? (Applause.) What becomes of the proffered freedom when they tell us that how far soever we may range in the search for truth, we must come back and square our results with the dogmas which are prescribed to us. (Applause.) We may go on collecting facts ; but when we study them, and presume to reason upon them, then it seems we go beyond our province, we 'descend from our eminence into the ordinary arena of hard logic;' we must submit our deductions to the decision of men who ostentatiously boast of their ignorance of the whole question, and who order us to stand till we are hooted and ridiculed before the world. (Applause.)
 As to the charge of insinuation that we use our scientific researches as a cloak for undermining the religious faith of the country. I take too much notice of it when I repel it with indignant scorn. (Applause.) Because, as geologists, we love to ponder over the past history of the planet of which we dwell, are we, therefore, to cease to have an interest with our fellow-men in our common Christianity? (Applause ) Had the men who thus speak of us lived a few centuries ago, they would have been found zealous defenders of Biblical astronomy ; but astronomy is now happily safe from them. They accept the deductions of that science implicitly, using them as arguments in favour of our religious belief, and proclaiming with triumph that 'the undevout astronomer is mad.' So, too, will it one day fare with geology. (Applause.) The men who now malign it will pass away, with all their littleness, and intolerance ; a new race will arise, finding in geology and its kindred agencies some of the firmest supports of true religion ; and Christianity, instead of being underminded and destroyed, will flourish still, as, after all, the best and greatest power on earth to elevate our race, to minister to its sufferings, and to point it onward and upward
   'To where beyond those voices there is peace."

--Edinburgh Daily Review, January 18.


Empire 9 April 1867

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