THE HISTORY AND PLACE IN SCIENCE OF THE "PRINCIPLES OF GEOLOGY."
The publication of the last volume of the "Principles of Geology" formed
an important epoch in Lyell's life. It brought to a successful close a
work on which his energies had been definitely concentrated for nearly
five years, and for which he had been preparing himself during a
considerably longer time. It placed him, before his fourth decade was
completed, at once and beyond all question in the front rank of British
geologists; it carried his reputation to every country where that
science was cultivated. It proved the writer to be not only a careful
observer and a reasoner of exceptional inductive power, but also a man
of general culture and a master of his mother tongue. The book,
moreover, marked an epoch in geology not less important; it produced an
influence on the science greater and more permanent than any work which
had been previously written, or has since appeared--greater even than
the famous "Origin of Species by Natural Selection," for that dealt only
with one portion of geology--viz. with palaeontology, while the method of
the Principles affected the science in every part. For a brief interval,
then, we may desert the biography of the author for that of the
book--the parent for his offspring--and call attention to one or two
topics which are more immediately connected with the book itself. A
brief sketch of its future history may be placed first; for, as its
author was constantly labouring to improve and perfect his work, it
underwent many changes in form and arrangement during the
remainder--some two-and-forty years--of his life, which will be better
understood from a connected statement than if they have to be gathered
from scattered references in the other chapters of his biography.
The first volume of the "Principles of Geology" appeared, as has been
mentioned, in January, 1830; the second in January, 1832; and the third
in May, 1833. But a second edition of the first volume was issued in
January, 1832, and one of the second volume in the same month of 1833;
these were all in 8vo size. A new edition of the whole work was
published in May, 1834. This, however, took the form of four volumes
12mo. This edition was called the third, because the first two volumes
of the original work had gone through second editions. A fourth edition
followed in June, 1835, and a fifth in March, 1837.
Thus far the "Principles" continued without any substantial alteration,
but the author made an important change in preparing the next edition.
He detached from it the latter part--practically, the matter comprised
in the third volume of the original work. This he rewrote and published
separately as a single volume in July, 1838, under the title of
"Elements of Geology"; a sixth edition of the "Principles," thus
curtailed, appeared in three volumes 12mo, in June, 1840. The effect of
the change was to restrict the "Principles" mainly to the physical side
of geology--to the subjects connected with the morphological changes
which the earth and its inhabitants alike undergo. Thus it made the
contents of the book accord more strictly with its title, while the
"Elements" indicated the working out of the aforesaid principles in the
past history of the earth and its inhabitants--that is, the latter book
deals with the classification of rocks and fossils, or with petrology
and historical geology. The subsequent history of the "Elements" may be
left for the present.
In February, 1847, the seventh edition of the "Principles" appeared, in
which another change was made. This, however, was in form rather than in
substance, for the book was now issued in a single thick 8vo volume. The
eighth edition, published in May, 1850; and the ninth, in June, 1853,
followed the same pattern. A longer interval elapsed before the
appearance of the tenth edition, and this was published in two volumes,
the first being issued in November, 1866, and the second in 1868. In
this interval--more than thirteen years--the science had made rapid
progress, and the process of revision had been in consequence more than
usually searching. The author, as he states in the preface, had "found
it necessary entirely to rewrite some chapters, and recast others, and
to modify or omit some passages given in former editions." Many new
instances were given to illustrate the effect which forces still at work
had produced upon the earth's crust, and these strengthened the evidence
which had been already advanced. Into the accounts of Vesuvius and Etna
much important matter was introduced, the result of visits which, as we
shall find, Lyell made in 1857 and 1858; the chapters relating to the
vicissitudes of climate in past geological ages were entirely rewritten,
together with that discussing the connection between climate and the
geography of the earth's surface; and a chapter, practically new, was
inserted, which considered "how far former vicissitudes in climate may
have been influenced by astronomical changes; such as variations in the
eccentricity of the earth's orbit, changes in the obliquity of the
ecliptic, and different phases of the precession of the equinoxes." But
the most important change was made in the later part of the book--the
last fifteen chapters.[55] These either were entirely new, or presented
the original material in a new aspect. In the earlier editions of his
work, Lyell had expressed himself dissatisfied, as we have already seen,
with the idea of the derivation of species from antecedent forms by some
process of modification, and had pointed out the weak places in the
arguments which were advanced in its favour. But the evidence adduced by
Darwin and Wallace in regard to the origin of species by natural
selection, strengthened by the support of Hooker on the botanical side,
had removed the difficulties which the cruder statements of Lamarck and
other predecessors had suggested to his mind, so that Lyell now appears
as a convinced evolutionist. The question also of the antiquity of man
is much more fully discussed than it had been in the earlier editions.
Considerable changes were introduced into the eleventh edition, which
appeared in January, 1872, but these were chiefly additions which were
made possible by the rapidly increasing store of knowledge, as, for
instance, much important information concerning the deeper parts of the
ocean. On this interesting subject great light had been thrown by the
cruises of the several exploring vessels, notably those of the
_Lightning_, the _Bulldog_, and the _Porcupine_, commissioned by the
British Government--cruises in the course of which soundings had been
taken and temperatures observed in the North Atlantic down to depths of
about 2,500 fathoms; and in the lowest parts of the western basin of the
Mediterranean. Samples also of the bottom had been obtained, and, in
many cases, even dredgers had been successfully employed at these
depths. Thanks to the skill of the mechanician, the way had been opened
which led into a new fairyland of science. This was not, like some
fabled Paradise, guarded by mountain fastnesses and precipitous ramparts
of eternal snow; it was not encircled by storm-swept deserts, or
secluded in the furthest recesses of forests, hitherto impenetrable; but
it lay deep in the silent abysses of ocean--on those vast plains, which
are unruffled by the most furious gale, or by the wildest waves. In
these depths, beneath the tremendous pressure of so vast a thickness of
water, and far below the limits at which the existence of life had been
supposed to be possible, numbers of creatures had been discovered--many
of them strange and novel: molluscs, sea-lilies, glassy sponges of
unusual beauty--creatures often of ancient aspect, relics of a fauna
elsewhere extinct; and the ocean floor, on and above which they moved,
was strewn with the white dust of countless coverings of tiny
foraminifera, which, even if none were actually living, had fallen like
a gentle but incessant rain from the overhanging mass of water.
Similar changes were introduced into the twelfth edition of the
"Principles," upon which the author was engaged even up to the last few
weeks of his life. The _Challenger_, it will be remembered, started on
her memorable voyage of exploration at the close of the year in which
the eleventh edition had appeared; and though she did not actually
return till after Lyell's death, notes of some of her most interesting
discoveries had been communicated from time to time to the scientific
journals of this country. The edition, however, was left incomplete. The
first volume had been passed for the press, but the second was still
unfinished; so that this twelfth edition was posthumous, the work of
revision having been finished by the author's nephew and heir, Mr.
Leonard Lyell.
By such conscientious and unremitting labour, the scientific value of
the "Principles" was immensely increased; it kept always in step with
the advance of the science, but at the same time it lost, as was
inevitable, a little of that literary charm and that sense of freshness
which was at first so marked a characteristic. Books, like children, are
apt to lose some of their beauty as they increase in size and strength.
One must compare an early and a late edition, such as the first or third
and the tenth or eleventh, in order to realise how great were the
changes in this passage from childhood to adolescence. New material was
incorporated into every part; it makes its appearance sometimes on every
page; changes are made in the order of the subjects; many chapters are
entirely rewritten; nevertheless, a considerable portion corresponds
almost word for word in the two editions. Lyell was no hurried writer,
or "scamper" of work; he paid great attention to composition, so that
when the facts which he desired to cite had undergone no change, he very
seldom found any to make in his language. Nevertheless, here and there,
some small modification, a slight verbal difference, a trifling
alteration in the order of a sentence, the insertion of a short clause
to secure greater perspicuity, shows to how careful and close a revision
the whole had been subjected. In the substance of the work, besides the
excision of nearly one-third of the material and the complete
reconstruction of the part relating to the antiquity of man and the
origin of species, already mentioned, the following are the most
important changes. The chapters which discuss the evidence in favour of
past mutations of climate and the causes to which these are due, are
rewritten and greatly enlarged. In the earlier editions, the effects of
geographical changes were regarded as sufficient to account for all the
climatal variations that geology requires; in the later editions, the
possible co-operation of astronomical changes is admitted. Great
additions also are made to the parts referring to the condition of the
bed of the ocean, and much new and important information is incorporated
into the sections dealing with volcanoes and earthquakes; including many
valuable observations which had been made during visits to Vesuvius and
to Etna in the autumns of 1857 and 1858. The section on the action of
ice is so altered and enlarged as to be practically new; for when the
first edition of the "Principles" was published comparatively little was
known of the effects of land-ice, and the art of following the trail of
vanished glaciers had yet to be learnt. But, with this exception, the
part of the book dealing with the action of the forces of Nature--heat
and cold, rain, rivers, and sea--remains comparatively unaltered, as do
the first five chapters, which give a sketch of the early history of the
science of geology.
Without some knowledge of this history it is hardly possible to
appreciate the true greatness of the "Principles," and its unique value
as an influence on scientific thought at the time it appeared. This,
however, to some extent may be inferred from those chapters which we
have mentioned; but the perspective of half a century enables us to
understand it better at the present time; for the author, of course, had
to deal with contemporary work and opinion only in a very indirect way.
We may dismiss briefly the crude speculations of the earliest
observers--those anterior to the Christian era--of which the author
gives a summary in the second chapter of the "Principles"; for at that
early date few persons had made any effort to arrange the facts of
Nature in a connected system. These were too scanty and too disconnected
for any such effort to be successful. The general result cannot be
better summed up than in Lyell's own words:--
"Although no particular investigations had been made for the
express purpose of interpreting the monuments of ancient
changes, they were too obvious to be entirely disregarded;
and the observation of the present course of Nature
presented too many proofs of alterations continually in
progress on the earth to allow philosophers to believe that
Nature was in a state of rest, or that the surface had
remained and would continue to remain, unaltered. But they
had never compared attentively the results of the destroying
and the reproductive operations of modern times with those
of remote eras; nor had they ever entertained so much as a
conjecture concerning the comparative antiquity of the human
race, or of living species of animals and plants, with those
belonging to former conditions of the organic world. They
had studied the movements and positions of the heavenly
bodies with laborious industry, and made some progress in
investigating the animal, vegetable, and mineral kingdoms;
but the ancient history of the globe was to them a sealed
book, and though written in characters of the most striking
and imposing kind, they were unconscious even of its
existence."[56]
The above remarks hold good for the centuries immediately succeeding the
Christian era; and the influence of the new faith, when it ceased to be
persecuted and became a power in the state, was adverse on the whole to
progress in physical or natural science. With the decline of the Roman
empire a great darkness fell upon the civilised world; art, science,
literature withered before the hot breath of war and rapine, as the
northern barbarians swept down upon their enfeebled master on their
errand of destruction. It was well nigh eight centuries from the
Christian era before the spirit of scientific enquiry and the love of
literature began to awaken from their long torpor; and it was then among
people of an Eastern race and an alien creed. The caliphs of Bagdad
encouraged learning, and the students of the East became familiar by
means of translations with the thoughts and questionings of ancient
Greece and Rome. The efforts of their earliest investigators have not
been preserved, but in treatises of the tenth century--written by one
Avicenna, a court physician, the "Formation and Classification of
Minerals" is discussed, as well as the "Cause of Mountains." In the
latter attention is called to the effect of earthquakes, and to the
excavatory action of streams. In the same century also, "Omar the
Learned" wrote a book on "the retreat of the sea," in which he proved by
reference to ancient charts and by other less direct arguments that
changes of importance had occurred in the form of the coast of Asia. But
even among the followers of Mohammed theology declared itself hostile to
science; the Moslem doctors of divinity deemed the pages of the Koran,
not the book of Nature, man's proper sphere of research, and considered
these difficulties ought to be settled by a quotation from the one
rather than by facts from the other. So progress in science was impeded,
and recantations at the bidding of ecclesiastics are not restricted to
the annals of Christian races. But men seem to have gone on speculating,
and Mohammed Kazwini, in a striking allegory which is quoted by Lyell,
tells his readers how (to use the words of Tennyson)[57]:--
"There rolls the deep where grew the tree.
O Earth, what changes thou hast seen!
There, where the long street roars, hath been
The stillness of the central sea."
In Europe geological phenomena do not appear to have attracted serious
attention till the sixteenth century, when the significance of fossils
became the subject of an animated controversy in Italy. At that epoch
this country held the front rank in learning and the arts, and an
inquiry of that nature arose almost as a matter of course, because the
marls, sands, and soft limestones of its lower districts teem in many
places with shells and other marine organisms in a singular state of
perfection and preservation. It is interesting to remark, that among the
foremost in appealing to inductive processes for the explanation of
these enigmas was that extraordinary and almost universal genius,
Leonardo da Vinci. He ridiculed the current idea that these shells were
formed "by the influence of the stars," calling attention to the mud by
which they were filled, and the gravel beds among which they were
intercalated, as proof that they had once lain upon the bed of the sea
at no great distance from the coast. His induction rested on the
evidence of sections which had been exposed during his construction of
certain navigable canals in the north of Italy. Shortly afterward, the
conclusions of Leonardo were amplified, and strengthened on similar
grounds by Frascatoro. He, however, not only demonstrated the absurdity
of explaining these organic structures by the "plastic force of
Nature"--a favourite refuge for the intellectually destitute of that and
even a later age, but he also showed that they could not even be relics
of the Noachian deluge. "That inundation, he observed, was too
transient; it had consisted principally of fluviatile waters; and if it
had transported shells to great distances, must have strewed them over
the surface, not buried them at vast depths in the interior of
mountains." As Lyell truly remarks, "His clear exposition of the
evidence would have terminated the discussion for ever, if the passions
of man had not been enlisted in the dispute; and even though doubts
should for a time have remained in some minds, they would speedily have
been removed by the fresh information obtained almost immediately
afterwards, respecting the structure of fossil remains, and of their
living analogues." But the difficulties raised by theologians, and the
general preference for deductive over inductive reasoning, greatly
impeded progress. It was not till the methods of the schoolmen yielded
place to those of the natural philosophers that the tide of battle began
to turn, and science to possess the domains from which she had been
unjustly excluded. For about a century the weary war went on; the
philosophers of Italy leading the van, those of England, it must be
admitted, for long lagging behind them, before the spectre of "plastic
force" was finally dismissed to the limbo of exploded hypotheses in
England. For instance, it was seriously maintained by the well-known
writer on county history, Dr. Plot, in the last quarter of the
seventeenth century, though its absurdity had been demonstrated by his
Italian contemporaries; as by Scilla, in his treatise on the fossils of
Calabria, and by Steno, in that on "Gems, crystals, and organic
petrifactions enclosed in solid rocks." The latter had proved by
dissecting a shark recently captured in the Mediterranean, that its
teeth and bones corresponded exactly with similar objects from a fossil
in Tuscany, and that the shells discovered in sundry Italian strata were
identical with living species, except for the loss of their animal
gluten and some slight mineral change. Moreover, he had distinguished,
by means of their organic remains, between deposits of a marine and of a
fluviatile character.
But now, as the "plastic force" dogma lost its hold on the minds of men,
its place was taken by that which regarded all fossils as the relics of
an universal deluge.
"The theologians who now entered the field in Italy,
Germany, France, and England, were innumerable; and
henceforward, they who refused to subscribe to the position
that all marine organic remains were proofs of the Mosaic
deluge, were exposed to the imputation of disbelieving the
whole of the sacred writings. Scarce any step had been made
in approximating to sound theories since the time of
Frascatoro, more than a hundred years having been lost in
writing down the dogma that organised fossils were mere
sports of Nature. An additional period of a century and a
half was now destined to be consumed in exploding the
hypothesis that organised fossils had all been buried in the
solid strata by Noah's flood."[58]
Into the varying fortunes of this second struggle it is needless to
enter at any length. It was the old conflict between theology and
science in a yet more acute form; the old warfare between deductive and
inductive reasoning; between dogmatic ignorance and an honest search for
truth. Protestants and Romanists alike seemed to claim the gift of
infallibility, with the right to decide _ex cathedra_ on questions of
which they were profoundly ignorant, and to pronounce sentence in causes
where they could not even appreciate the evidence. Ecclesiastics
scolded; well-meaning though incompetent laymen echoed their cry; the
more timorous among scientific men wasted their time in devising
elaborate but futile schemes of accommodation between the discoveries of
geology and the supposed revelations of the Scriptures; the stronger
laboured on patiently, gathering evidence, strengthening their arguments
and dissecting the fallacies by which they were assailed, until the
popular prejudice should be allayed and men be calm enough to listen to
the voice of truth. It was a long and weary struggle, which is now
nearly, though not quite, ended; for there are still a few who mistake
for an impregnable rock that which is merely the shifting-sand of
popular opinion, and cannot realise that the province of revelation is
in the spiritual rather than in the material, in the moral rather than
in the scientific order. The outbursts of denunciation aroused by the
assertion of the antiquity of man and the publication of the "Origin of
Species," which many still in the full vigour of their powers can well
remember, were but a recrudescence of the same spirit, a reappearance of
an old foe with a new face.
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 scoriae, 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 Geikie[62]:--
"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 Phoenix-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 palaeontological, 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 palaeontologist; 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
palaeontology 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 palaeontological 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 follows[65]: (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.
FOOTNOTES:
[55] Strictly speaking, fifteen out of the last sixteen chapters, for
the final one (dealing with coral reefs) is substantially a reprint.
[56] "Principles of Geology," vol. i. p. 26 (eleventh edition).
[57] _In Memoriam_, cxxiii.
[58] "Principles of Geology," chap. iii. p. 37.
[59] "Principles of Geology," chap. iv.
[60] "Principles of Geology," chap. iv.
[61] Hutton's "Theory of the Earth" was first published in 1788, and in
an enlarged form in 1795. Playfair's "Illustrations of the Huttonian
Theory" appeared in the spring of 1802.
[62] Geikie's "Life of Murchison," chap. vii.
[63] "Principles of Geology," chap. iv.
[64] "Principles of Geology," chap. iv.
[65] Abridged from Lyell's summary: "Principles of Geology," chap. vii.