Charles Lyell and Modern Geology

But when Lyell was young and the idea of the "Principles" began to germinate in his mind, popular prejudice against the free exercise of inquiry in geology was still strong; this diluvial hypothesis still hampered, if it did not fully satisfy, the majority of scientific workers. Here and there, it is true, some isolated pioneer demonstrated the impossibility of referring the fossil contents of the earth's crust to a single deluge, or protested against the singular mixture of actual observation, patristic quotation, and deductive reasoning which commonly passed current for geological science. Chief and earliest among these men, Vallisneri, also an Italian, about a century before Lyell's birth, was clearsighted enough to see "how much the interests of religion as well as those of sound philosophy had suffered by perpetually mixing up the sacred writings with questions in physical science"; indeed, he was so far advanced as to attempt a general sketch of the marine deposits of Italy, with their organic remains, and to arrive at the conclusion that the ocean formerly had extended over the whole earth and after remaining there for a long time had gradually subsided. This conclusion, though inadequate as an expression of the truth, was much more philosophical than that of an universal and comparatively recent deluge. Moro and Generelli, in the same country, followed the lead of Vallisneri, in seeking for hypotheses which were consistent with the facts of Nature, Generelli even arriving at conclusions which, in effect, were those adopted by Lyell, and have been thus translated by him:

"Is it possible that this waste should have continued for six thousand and perhaps a greater number of years, and that the mountains should remain so great unless their ruins have been repaired? Is it credible that the Author of Nature should have founded the world upon such laws as that the dry land should be for ever growing smaller, and at last become wholly submerged beneath the waters? Is it credible that, amid so many created things, the mountains alone should daily diminish in number and bulk, without there being any repair of their losses? This would be contrary to that order of Providence which is seen to reign in all other things in the universe. Wherefore I deem it just to conclude that the same cause which, in the beginning of time, raised mountains from the abyss, has down to the present day continued to produce others, in order to restore from time to time, the losses of all such as sink down in different places, or are rent asunder, or in other ways suffer disintegration. If this be admitted, we can easily understand why there should now be found upon many mountains so great a number of crustacea and other marine animals."

This attempt at a system of rational geology was a great advance in the right direction, though many gaps still remained to be filled up and some errors to be corrected; such for instance as the idea adopted by Generelli from Moro, and maintained in other parts of his work, that all the stratified rocks are derived from volcanic ejections. Nevertheless, geology, by the middle of the eighteenth century, had evidently begun to pass gradually, though very slowly, from the stage of crude and fanciful hypotheses to that of an inductive science. But even then the observers had only succeeded in setting foot on the lower slopes of a peak, the summit of which will not be reached, if indeed it ever be, for many a long year to come. During the next half of the century progress was made, now in this direction, now in that; slowly truths were established, slowly errors dispelled; and as the close of that century approached, the foundations of modern geology began to be securely laid. A great impulse was given to the work, though to some extent the apparent help proved to be a real hindrance, by that famous teacher, Werner of Freiberg, in Saxony. His influence was highly beneficial, because he insisted not only on a careful study of the mineral character of rocks, but also on attending to their grouping, geographical distribution, and general relations. It was hurtful almost to as great a degree, because he maintained, and succeeded by his enthusiasm and eloquence in impressing on his disciples, most erroneous notions as to the origin of basalts and those other igneous rocks which were formerly comprehended under the name "trap." Such rocks he stoutly asserted to be chemical precipitates from water, and, besides this, he held views in general strongly opposed to anything like the action of uniform causes in the earth's history. In short, the Saxon Professor was in many respects the exact antithesis of Lyell, and the points of essential contrast cannot be better indicated than in the words of the latter.59

"If it be true that delivery be the first, second, and third requisite in a popular orator, it is no less certain that to travel is of first, second, and third importance to those who desire to originate just and comprehensive views concerning the structure of our globe. Now Werner had not travelled to distant countries; he had merely explored a small portion of Germany, and conceived, and persuaded others to believe, that the whole surface of our planet and all the mountain-chains in the world were made after the model of his own province. It became a ruling object of ambition in the minds of his pupils to confirm the generalisations of their great master, and to discover in the most distant parts of the globe his 'universal formations,' which he supposed had been each in succession simultaneously precipitated over the whole earth from a common menstruum or chaotic fluid."

These wild generalisations, as Lyell points out, had not even the merit of being really in accordance with the evidence afforded by some parts of Saxony itself. Werner, in fact, was a conspicuous example of a tendency, which perhaps even now is not quite extinct, to work too much beneath a roof and too little in the open air; to found great generalisations on the minute results of research in a laboratory, without subjecting them to actual tests by the study of rocks in the field.

This error on Werner's part was the less excusable, because, even before he began to lecture, the true nature of basalts and traps generally had been recognised by several observers of different nationalities. In the Hebrides and in Iceland, in the Vicentin and in Auvergne, even in Hesse and in the Rheingau, proof after proof had been cited, and the evidence in favour of the "igneous" origin of these rocks had become irresistible, as one might suppose, within some half dozen years of Werner's appointment as professor at Freiberg. Faujas, in 1779, published a description of the volcanoes of the Vivarais and Velay, in which he showed how the streams of basalt had poured out from craters which still remain in a perfect state. Desmarest also pointed out that in Auvergne "first came the most recent volcanoes, which had their craters still entire and their streams of lava conforming to the level of the present river courses. He then showed that there were others of an intermediate epoch, whose craters were nearly effaced, and whose lavas were less intimately connected with the present valleys; and lastly, that there were volcanic rocks still more ancient without any discernible craters or scoriæ, and bearing the closest analogy to rocks in other parts of Europe, the igneous origin of which was denied by the school of Freiberg." Desmarest even constructed and published a geological map of Auvergne, of which Lyell speaks in terms of high commendation. "They alone who have carefully studied Auvergne, and traced the different lava streams from their craters to their termination – the various isolated basaltic cappings – the relation of some lavas to the present valleys – the absence of such relations in others – can appreciate the extraordinary fidelity of this elaborate work."60

But before the close of the eighteenth century, two champions had already stepped into the arena to withstand the Wernerian hypothesis, which, like a swelling tide, was spreading over Europe, and threatening to sweep away everything before it. These were James Hutton and William Smith; the one born north, the other south of the Tweed. From the name of the former that of his friend and expositor, John Playfair, must never be separated. They were the Socrates and the Plato of that school of thought from which modern geology has been developed.61 To quote the eloquent words of Sir Archibald Geikie62: —

"On looking back to the beginning of this century we see the geologists of Britain divided into two hostile camps, which waged against each other a keen and even an embittered warfare. On the one hand were the followers of Hutton of Edinburgh, called from him the Vulcanists, or Plutonists; on the other, the disciples of Werner … who went by the name of Wernerians, or Neptunists… The Huttonians, who adhered to the principles laid down by their great founder, maintained, as their fundamental doctrine, that the past history of our planet is to be explained by what we can learn of the economy of Nature at the present time. Unlike the cosmogonists, they did not trouble themselves with what was the first condition of the earth, nor try to trace every subsequent phase of its history. They held that the geological record does not go back to the beginning, and that therefore any attempt to trace that beginning from geological evidence was vain. Most strongly, too, did they protest against the introduction of causes which could not be shown to be a part of the present economy. They never wearied of insisting that to the everyday workings of air, earth, and sea, must be our appeal for an explanation of the older revolutions of the globe. The fall of rain, the flow of rivers, the slowly crumbling decay of mountain, valley, and shore, were one by one summoned as witnesses to bear testimony to the manner in which the most stupendous geological changes are slowly and silently brought about. The waste of the land, which they traced everywhere, was found to give birth to soil – renovation of the surface thus springing Phœnix-like out of its decay. In the descent of water from the clouds to the mountains, and from the mountains to the sea, they recognised the power by which valleys are carved out of the land, and by which also the materials worn from the land are carried out to the sea, there to be gathered into solid stone – the framework of new continents. In the rocks of the hills and valleys they recognised abundantly the traces of old sea-bottoms. They stoutly maintained that these old sea-bottoms had been raised up into dry land from time to time by the powerful action of the same internal heat to which volcanoes owe their birth, and they pointed to the way in which granite and other crystalline rocks occur as convincing evidence of the extent to which the solid earth has been altered and upheaved by the action of these subterranean fires."

Such were the leading principles of the "Huttonian theory," though perhaps they are stated here in a slightly more developed form than when it was first presented by its illustrious author. But it was defective in one important respect, on a side from which it might have obtained the strongest support, and have liberated itself from the bondage of deluges; in other words, of convulsive action, by which it was still fettered, for "it took no account of the fossil remains of plants and animals. Hence it ignored the long succession of life upon the earth which those remains have since made known, as well as the evidence thereby obtainable as to the nature and order of physical changes, such as alternations of sea and land, revolutions of climate, and suchlike."

This defect was supplied by William Smith. He had learnt, by patient labour among the stratified rocks of England, to recognise their fossils, had ascertained that certain assemblages of the latter characterised each group of strata, and by this means had traced such groups through the country, and had placed them in order of superposition. So early as 1790, he published a "Tabular View of the British Strata," and from that time was engaged at every spare moment in constructing a geological map of England, all the while freely communicating the results of his researches to his brethren of the hammer. "The execution of his map was completed in 1815, and it remains a lasting monument of original talent and extraordinary perseverance; for he had explored the whole country on foot without the guidance of previous observers, or the aid of fellow labourers, and had succeeded in throwing into natural divisions the whole complicated series of British rocks."63

A most important step in view of future progress, at any rate in our own country, was taken by the foundation of the Geological Society of London in 1807, the members of which devoted themselves at first rather to the collection of facts than to the construction of theories, while in France the labours of Brongniart and Cuvier in comparative osteology, and of Lamarck in recent and fossil shells, smoothed the way toward the downfall of catastrophic geology. Those men, with their disciples, "raised these departments of study to a rank of which they had never before been deemed susceptible. Their investigations had eventually a powerful effect in dispelling the illusion which had long prevailed concerning the absence of analogy between the ancient and modern state of our planet. A close comparison of the recent and fossil species, and the inferences drawn in regard to their habits, accustomed the geologist to contemplate the earth as having been at successive periods the dwelling-place of animals and plants of different races – some terrestrial, and others aquatic; some fitted to live in seas, others in the waters of lakes and rivers. By the consideration of these topics the mind was slowly and insensibly withdrawn from imaginary pictures of catastrophes and chaotic confusion, such as haunted the imagination of the early cosmogonists. Numerous proofs were discovered of the tranquil deposition of sedimentary matter, and the slow development of organic life."64

Such was the earlier history of Geology; such were the influences which had moulded its ideas till within a few years of the date when Lyell began to make it a subject of serious study. At that time, namely about the year 1820, the Geological Society of London had become the centre and meeting-point of a band of earnest and enthusiastic workers, whose names will always hold an honoured place in the annals of the Science. Among the older members – most of whom, however, were still in the prime of life, were such men as Buckland, Conybeare, Fitton, Greenough, Horner, MacCulloch, Warburton and Wollaston; among the younger, De la Beche and Scrope, Sedgwick and Whewell. Murchison, though a few years Lyell's senior, was by almost as many his junior as a geologist, for he did not join the Society till the end of 1824, and was actually admitted on the evening when Lyell, then one of its honorary secretaries, read his first paper – on the marl-lake at Kinnordy. Such men also as Babbage, Herschel, Warburton, Sir Philip Egerton, the Earl of Enniskillen (then Viscount Cole), must not be forgotten, who were either less frequent visitors or more directly devoted to other studies. At this time geology was passing into a phase which endured for some forty years – the exaltation of the palæontological, the depreciation of the mineralogical side. If it be true, as it has been more than once remarked, that the father of the geologist was a mineralogist, it is no less true that his mother was a palæontologist; but at this particular epoch the paternal influence obviously declined, while that of the mother became inordinately strong. Wollaston and MacCulloch, indeed, were geologists of the old school; excellent mineralogists and petrologists (to use the more modern term) as accurate as it was possible to be with the appliances at their disposal, but among the younger men De la Beche, accompanied to a certain extent by Scrope and Sedgwick, was almost alone in following their lead. But although palæontology and stratigraphical geology as its associate were clearly making progress, the school of thought, of which Lyell became the champion, counted at this time but few adherents, for the older geologists were almost to a man "catastrophists." A few, like MacCulloch, undervalued palæontological research, and thus were doubly prejudiced against the uniformitarian views. Buckland, Conybeare, Greenough, as we have already seen from incidental remarks in Lyell's letters, had put their trust in deluges, and imagined that by such an agency the earth had been prepared for a new creation of living things and a new group of geological formations. Sedgwick even was to a great extent on their side. He had speedily emerged from the waters of Wernerism, in which at first he had been for a short time immersed, but he did not escape so easily from the roaring floods of diluvialists, and the grandeur of catastrophic changes in the crust of the earth fascinated his enthusiastic, almost poetic, nature. Even so late as 1830, we find him criticising from the chair of the Geological Society the leading argument of Lyell's "Principles of Geology" in no friendly spirit, and bestowing high praise on Elie de Beaumont's theory of Parallel Mountain-chains.

A brief summary of the views advocated by this eminent French geologist may serve to indicate, perhaps better than any general statements, the influences against which Lyell had to contend at the outset of his career as a geologist. With the omission of certain parts, to which no exception would be taken, or which have no very direct bearing upon the immediate question, they are as follows65: (1) In the history of the earth there have been long periods of comparative repose, during which the sedimentary strata have been continuously deposited, and short periods of paroxysmal violence, during which that continuity has been interrupted. (2) 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, and these chains, if contemporaneous, are parallel; but if not so, generally differ in direction. (3) Each revolution or great convulsion has coincided with the date of another geological phenomenon, namely, the passage from one independent sedimentary formation to another, characterised by a considerable difference in "organic types." (4) There has been a recurrence of these paroxysmal movements from the remotest geological periods; and they may still be produced.

Thus the force of authority, which has to be reckoned with in geology, if not in other branches of science, was in the main adverse to Lyell, who could count on but few to join him in his attack on catastrophism. One indeed there was, a host in himself, who, though his contemporary in years, had devoted himself wholly to geology at a slightly earlier date and had already become convinced, by his field-work in Italy and France, of the efficacy of existing forces to work mighty changes, if time were given, in the configuration of the earth's surface. This was George Poulett Scrope, a man of broad culture, great talents, and singular independence of thought, who had convinced himself of the errors of the Wernerian theory by his studies in Italy in the years 1817-19, and had thoroughly explored the volcanic district of Auvergne in 1821. His work on the Phenomena of Volcanoes, published in 1823, and that on the Geology of Central France, published in 1826, had given the coup de grace to Werner's hypothesis and had made the first breach in the fortress of the catastrophists.

For a complete solution of the problem to which Lyell had addressed himself, two methods of investigation were necessary. It must be demonstrated that in tracing back the life history of the earth from the present age to a comparatively remote past no breach of continuity could be detected, and that the forces which were still engaged in sculpturing and modifying this earth's surface were adequate, given time enough, to produce all those changes to which the catastrophist appealed as proofs of his hypotheses. To establish the one conclusion, it was necessary to make a careful study of the Tertiary formations, which were still in a condition of comparative confusion; to arrange them in an order no less clear and definite than that of the Secondary systems; and to show, by working downward from the present fauna, not only that many living species had been long in existence, but also that these had appeared gradually, not simultaneously, and had in like manner replaced forms which had one after another vanished – to prove, in short, "that past and present are bound together by an unsevered cord of life, whose interlacing strands carry us back in orderly change from age to age." To establish the other conclusion it was necessary to show that, even in historical times, considerable changes had occurred in the outlines of coasts, and that heat and cold, the sea, or rain and rivers – especially the last – had been agents of the utmost importance in the sculpture of cliffs, valleys, and hills. For both these purposes careful study, not only in Britain, but also still more in other regions, was absolutely necessary, and it was with them in view that Lyell undertook his journeys, from the time when his geological ideas began to assume a definite shape until the last volume of the "Principles" was published. By that date, as has been stated in the preceding chapters, he had made himself familiar in the course of his geological education with many parts of Britain, had laboriously investigated the more important collections and museums of France and Italy, and had carefully studied in the field the principal Tertiary deposits not only in these countries but also in Sicily and in parts of Switzerland and Germany. To obtain evidence bearing on the physical aspect of the question on a scale grander than was afforded by the undulating lowlands, or worn-down highland regions of Britain and the neighbouring parts of Europe, he had rambled among the Alps and Pyrenees, examining their peaks and precipices, their snowfields, glaciers, lakes, and torrents, and watching the processes of destruction, transportation, and deposition of which crag, stream, and plain afford a never-ending object-lesson. In order to study volcanoes still in activity, he had climbed Vesuvius and Etna; in order to scrutinise more minutely the structure of cones, craters, and lava streams, he had visited Auvergne, Catalonia, and the Eifel; while in all his goings and comings through scenes where Nature worked more unobtrusively, he had watched her never-ending toil, as she destroyed with the one hand and built with the other. He was thus able to write with the authority of one who has seen, not of one who merely quotes; of one who knew, not of one who had learnt by rote. The "Principles of Geology," though of course it had to rely not seldom on the work of others, bore the stamp of the author's experience, and was redolent, not of the dust of libraries, but of the sweetness of the open air. That fact added no little force to its cautious and clear inductive reasoning; that fact did much to disarm opposition, and to open the way to victory.

CHAPTER VI.

EIGHT YEARS OF QUIET PROGRESS

Both courses of lectures ended66 and the third volume of the "Principles" successfully launched, Mr. and Mrs. Lyell left London in June, 1833, for another Continental tour. During their first halt, at Paris, she was duly introduced to the famous quarries of Montmartre, and had an opportunity of "collecting a fossil shell or two for the first time." Thence they made their way to Bonn, which she had left as a bride the previous summer, and, after another short halt, proceeded up the gorge of the Rhine to Bingen, visiting on the way the ironworks at Sayn, and examining the stratified volcanic deposits on the plain between the river and that town. The Tertiary basin at Mayence was next visited, and from it they went leisurely to Heidelberg. From the picturesque old town by the Neckar they struck off to Stuttgart and to Pappenheim, examining one or two collections at the former place, and the quarries of Solenhofen, near the latter. These were already noted for the abundant and well-preserved fossils obtained in the quarries worked for the well-known "lithographic stone," though the famous Archæopteryx had yet to be found; that strange creature, feathered and like a bird, but with teeth in its beak and a tail like a reptile, which has supplied such an important link in the chain of evidence in favour of progressive development. Thence they travelled to Nürnberg and Bayreuth, visiting on their way the noted caves at Muggendorf, and returned to Bonn by way of Bamberg, Würtzburg, Aschaffenberg, and Frankfurt. In this journey, few localities of special interest were investigated, but, as Lyell's letters show, no opportunity was lost of discussing important questions with local geologists, or of examining sections in the field. But on the way back to England through Belgium a halt was made at Liége, to inspect Dr. Schmerling's grand collection of cave-remains. It is evident, though but a short notice of it has been preserved, that this visit kindled an enthusiasm which was to produce important results in later years. Lyell writes (to Mantell, after his return to England): —