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Full text of "Charles Darwin as geologist. The Rede lecture given at the Darwin centennial commemoration on 24 June 1909"

30 CHARLES DARWIN 

have been led to adopt the views promulgated 
in this remarkable paper. He had himself 
witnessed a severe earthquake, and could 
speak from personal knowledge of its effects 
in a region which had often been convulsed 
by similar events. He had found that one 
of these effects was a marked uplift of some 
parts of the coast-line. He had beheld with 
his own eyes the simultaneous and violent 
activity of two of the great volcanoes of 
the Cordillera 33 . Pondering on these mighty 
manifestations of terrestrial energy, and re- 
membering what a long succession of volcanic 
periods he had detected in the framework 
of the continent, he conceived not only that 
earthquakes and volcanoes are intimately 
related to each other, as was then generally 
believed, but that they both proceed from 
movements in the internal molten material 
of the globe. Although the origin of these 
movements was shrouded from him, he be- 
came convinced, to use his own impressive 
words, that "the configuration of the fluid 
surface of the earth's nucleus is subject to 



AS GEOLOGIST 31 

some change its cause completely unknown, 
its action slow, intermittent, but irresistible 34 ." 
These theoretical views seemed at the time 
to be warranted by all the evidence which 
had then been obtained on the subject, and 
more especially by the large body of proof 
which the author himself had gathered to- 
gether. But the extended researches of later 
years in seismology and mountain-building 
have brought to light much information which 
he did not possess. We now know that there 
is no such general and intimate relation, as 
was then assumed, between earthquakes and 
volcanoes; for many gigantic earthquakes 
have taken their origin at a distance from 
active volcanoes, while vigorous volcanic 
energy is not always accompanied with earth- 
quakes or with permanent alterations in the 
relative levels of sea and land. Since his 
time, too, the complicated structure of 
mountain-chains has been elucidated in much 
detail. We have learnt how intensely, along 
these tracts of elevated ground, the terrestrial 
crust has been folded, crumpled, fractured 



! BERK ELEVEN 
LIBRARY 
JNIVERSITY OF 1 
CALIFORNIA I 



I/BRA/?'- 





THE LIBRARY 

OF 

THE UNIVERSITY 
OF CALIFORNIA 

PRESENTED BY 

PROF. CHARLES A. KOFOID AND 
MRS. PRUDENCE W. KOFOID 



CHARLES DARWIN 
AS GEOLOGIST 



CAMBRIDGE UNIVERSITY PRESS 

HottiJon: FETTER LANE, E.G. 

C. F. CLAY, MANAGER 




100, PRINCES STREET 

Berlin: A. ASHER AND CO. 

Leipzig: F. A. BROCKHAU8 

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CHARLES DARWIN 
AS GEOLOGIST 

THE REDE LECTURE 

GIVEN AT THE DARWIN CENTENNIAL COMMEMORATION 
ON 24 JUNE 1909 



BY 



SIR ARCHIBALD GEIKIE, K.C.B. 
D.Sc., D.C.L."(OxoN.) 

PRESIDENT OF THE ROYAL SOCIETY 



Cambridge : 

at the University Press 

1909 



Cambridge i 

PRINTED BY JOHN CLAY, M.A 
AT THE UNIVERSITY PRESS 



CHARLES DARWIN AS GEOLOGIST 

When the Vice-Chancellor honoured me 
with his invitation to give the Rede Lecture 
this year, he informed me that it would be 
included in the proceedings of the present 
Celebration. Although he left me free in the 
choice of a subject, it was obvious that the 
lecturer could hardly hesitate to select a 
theme which would have reference, more or 
less direct, to the illustrious Naturalist whose 
Centenary the University had resolved to 
commemorate. The nature and extent of 
Charles Darwin's contributions to biological 
science have been so often and so fully 
described, and his influence on almost all 
departments of human thought has been so 
amply recognised, that for the present, little 
more may seem to remain to be said on the 
subject until, in the course of time, a fresh 

G. 1 



CHARLES DARWIN 



review of his relations to the history of 
intellectual development may be called for. 
Nevertheless, I venture to think that there is 
one branch of his scientific labours, the value 
and significance of which have scarcely 
perhaps received the notice and appreciation 
to which they are entitled. It is- apt to be 
forgotten that Darwin began his active scien- 
tific career as a geologist, that it was mainly 
to geological problems that the earlier years 
of his life were devoted, and that it was in no 
small measure from the side of geology that 
he was led into those evolutional studies 
which have given him so just a title to our 
admiration and gratitude, and have placed 
him so high among the immortals. I have 
therefore decided to ask your attention to-day 
to an outline of what he accomplished in 
geology, and of the relation of his studies iu 
that science to the great problems of evolu- 
tion with which his name is indissolubly 
associated. 

In Darwin's younger days geology had 
hardly as yet completely vindicated for itself 



AS GEOLOGIST 



an acknowledged and assured place in the 
circle of the natural sciences. Those who 
then cultivated it could not agree among 
themselves upon its fundamental principles. 
They were divided into three distinct and 
antagonistic schools, between whom a long 
and sometimes acrimonious controversy was 
waged. /On the one side, the Neptunists, or 
Champions of Water, maintained, as the prime 
article of their creed, that our planet was 
once enveloped in an universal ocean, from 
which the various rocks now to be seen in 
its crust were deposited as chemical and 
mechanical precipitates. They ridiculed the 
notion that the globe had a heated interior, 
and they regarded volcanoes as a late appear- 
ance in the earth's history, due to the spon- 
taneous combustion of subterraneous beds of 
coal 1 *. On the other side the Vulcanists, or 
Plutonists, with Fire as their watchword, 
vehemently insisted on the important part 
which they believed had been taken by the 
globe's internal heat, whether in the form of 
* The figures in the text refer to the Notes at the end. 

12 



CHARLES DARWIN 



volcanoes or by the subterranean intrusion of 
molten material into the solid crust 2 . But 
this school was split into two parties who 
opposed each other with hardly less vigour 
than they both showed towards the Neptunists. 
The one section proclaimed that the pheno- 
mena revealed by geology bear witness to a 
far greater intensity of action in former ages 
than now, and especially to the occurrence 
from time to time of gigantic cataclysms 
whereby the face of the planet was changed, 
whole tribes of plants and animals were 
destroyed, and place was made for the crea- 
tion of new faunas and floras. Those who 
belonged to this division were known as the 
Catastrophic or Convulsionist school 3 . The 
other section received the name of Uniformi- 
tarian, inasmuch as they held that Nature's 
operations have always been carried on much 
as they are now, that instead of being marked 
by periodical frenzies of eftergy, her action 
has been generally uniform, and that thus the 
Present may be taken as the Key to the 
Past 4 . / It is interesting to find that Darwin 



AS GEOLOGIST 



in his youth had personal relations with 
some of the leaders in each of these three 
camps. 

When as a lad of sixteen he went to the 
University of Edinburgh he found himself 
at the headquarters of the Neptunists in this 
country. The Professor of Natural History 
there, Robert Jameson, had been trained at 
Freiberg under Werner, the great law-giver 
of the Neptunist cult, and for more than 
twenty years had been carrying on an active 
propagandism of Wernerian doctrines, which 
have long since been abandoned as illogical 
and absurd. Darwin has recorded that he 
found the lectures " incredibly dull." He 
particularly refers to an excursion to Salis- 
bury Craigs, near Edinburgh, where, with 
volcanic rocks all around, he heard the pro- 
fessor actually declare that "a trap-dyke, with 
amygdaloidal margins and the strata in- 
durated on each side, was a fissure filled with 
sediment from above, adding with a sneer 
that there were men who maintained that it 
had been injected from beneath in a molten 



CHARLES DARWIN 



condition." The young student had sharp 
enough eyes to see the true state of the case 
and sufficient independence to follow his own 
judgment in the matter. Well might he long 
afterwards remark, "When I think of this 
lecture I do not wonder that I determined 
never to attend to Geology 5 ." 

But fortunately for the science this deter- 
mination disappeared when a few years 
afterwards he discovered that the Wernerism 
which he had been taught at Edinburgh by 
no means represented the real character and 
aim of geological studies. He tells us that 
during the last of the three years which he 
spent at Cambridge he read Humboldt's 
Personal Narrative and Herschel's Prelimi- 
nary Discourse on the Study of Natural 
Philosophy, and he adds that "no one or a 
dozen other books influenced him nearly so 
much as these two 6 ." Herschel's admirable 
little volume with its logical presentation of 
scientific method, and Humboldt's glowing 
pictures of tropical scenery and wide outlook 
into all domains of science might well kindle 



AS GEOLOGIST 



in him a keen desire to follow in the paths of 
scientific travel. 

It was in the spring of the year 1831, when 
these influences were at work on Darwin's 
mind, that he was persuaded by his sagacious 
and accomplished tutor, John Stevens Hen- 
slow, " to begin the study of geology." His 
first essays in field-work appear to have been 
made in the summer of that year when, to 
use his own words, he " worked like a tiger " 
among the geological sections around Shrews- 
bury, trying to fill in geological details upon a 
map of that district a task which proved less 
easy than he expected?. Henslow introduced 
him to Adam Sedgwick, the distinguished 
Woodwardian Professor at Cambridge, with 
whom he made a geological excursion that 
autumn through a part of North Wales. 
Doubtless practical lessons from so accom- 
plished and inspiring a leader were of no 
little service to Darwin in fostering his 
growing geological enthusiasm and teaching 
him the methods of observation in the field. 
We may be sure, too, that he was privileged 



CHARLES DARWIN 



to listen to much instructive and vigorous 
discourse, not only on the local geology, but 
on many of the wider bearings of the science. 
Sedgwick was a stout champion of the con- 
vulsionist creed, which he no doubt inculcated 
on his pupil as the true faith. That Darwin 
at first had himself some predilections in 
the same direction may perhaps be inferred 
from one of his letters to Henslow, in which, 
speaking of his geological doings in Shrop- 
shire before the excursion into North Wales, 
he said that he had " only indulged in hypo- 
theses, but they are such powerful ones that, 
I suppose, if they were put into action but 
for one day, the world would come to an end 8 ." 
The first volume of Lyell's immortal 
Principles of Geology was published in the 
month of January 1830 9 . Although this work 
was eventually to have so profound an in- 
fluence on the progress of geological science, 
it was received at first with doubt and oppo- 
sition. In spite of its singularly luminous 
presentation of the whole connected system 
of natural operations that modiiy the surface 



AS GEOLOGIST 



of the globe, alike in the organic and in- 
organic kingdoms, notwithstanding its over- 
whelming array of evidence drawn from all 
quarters of the earth and the clear and 
eloquent language in which the logical 
deductions from this evidence were enforced, 
the whole spirit and aim of the book ran so 
directly counter to the tenets of the prevalent 
convulsionist school that it seemed for a time 
to reawaken the fires of controversy which 
had for years been gradually waxing dim. 
Its uniformitarianism, carried even to further 
lengths than Hutton and Playfair had ven- 
tured to go, was denounced with character- 
istic vigour by Sedgwick from the chair of the 
Geological Society 4 . Even so judicious and 
impartial a counsellor as Henslow, when he 
advised Darwin to procure and study Lyell's 
treatise, w r arned him "on no account to accept 
the views therein advocated 10 ." The young 
geologist followed the advice of his tutor, 
but not the proviso with which it was accom- 
panied. He took the book with him on the 
voyage of the Beagle and studied it with 



10 CHARLES DARWIN 

enthusiasm, and with a result the very reverse 
of what Henslow desired. In recording, 
among the Cape de Verde Islands, the first 
observations made by him on foreign soil, he 
affirms that "they convinced me of the infinite 
superiority of Lyell's views over those advo- 
cated in any other work known to me 11 ." In 
this way began that life-long indebtedness to 
Lyell which he sincerely felt, and never ceased 
to express. 

In reviewing the nature and value of 
Darwin's geological work on the voyage of 
the Beagle, we must bear in mind the con- 
ditions under which it was undertaken. In 
the first place, he had only begun, a few 
months before, to turn his attention to the 
study of geology, and although he had doubt- 
less worked hard at the subject during that 
brief interval, his knowledge and practical 
experience in it could hardly be other than 
limited. Further, it should be remembered 
that as the vessel was continually cruising 
from place to place, never remaining more 
than a short time at anchor, he had scant 



AS GEOLOGIST 11 

opportunity of completing a detailed study 
of any locality. His observations had often 
to be made under the pressure of a limitation 
in the number of days, or sometimes even 
of hours, that were available. In the most 
favourable circumstances, little more than a 
first broad sketch of the geology of each 
place could reasonably be expected. But 
Charles Darwin was no ordinary observer. 
From the very beginning of the voyage he 
displayed a zeal and aptitude for geological 
work which in a short time enabled him to 
gather together an astonishing amount of 
valuable detail, while at the same time he 
rapidly gained experience in noting the wider 
bearing of the facts that came under his eye, 
and in drawing far-reaching and suggestive 
conclusions from them. 

The enthusiasm with which he pursued 
his geological enquiries on the voyage is 
charmingly revealed in his letters and his 
Journal. The very first land at which the 
Beagle touched on her outward voyage 
gave him the opportunity of beginning his 



12 CHARLES DARWIN 

field-work on the old volcanic ground of 
St Jago, one of the Cape de Verde Islands. 
Wandering over its mouldering lava-streams 
and fired with fresh zeal from his eager 
perusal of the first volume of the Principles 
of Geology he realised, as he wrote in later 
years, "the wonderful superiority of Lyell's 
manner of treating geology, compared with 
that of any other author whose works I had 
with me or ever afterwards read 12 ." It was 
there under the spell of this great teacher 
that, as he has recorded, " it first dawned on 
me that I might perhaps write a book on the 
geology of the various countries visited, and 
this made me thrill with delight 13 ." This 
geological ardour lasted undimmed through- 
out the whole of the five years of the 
Beagle's voyage. When after his first cross- 
ing of the Atlantic he began his explora- 
tions on South American soil, he wrote of 
his voyage and its incidents : " Geology carries 
the day; it is like the pleasure of gambling. 
Speculating on arriving what the rocks may 
be, I often mentally cry out ' 3 to 1 Tertiary 



AS GEOLOGIST 13 

against Primitive'; but the latter have 
hitherto won all the bets 14 ." In sending home 
his collections from Brazil he wrote to Hen- 
slow that "the box contains a good many 
geological specimens; I am well aware that 
the greater number are too small. But I 
maintain that no person has a right to accuse 
me till he has tried carrying rocks under a 
tropical sun. I have endeavoured to get 
specimens of every rock, and have written 
notes upon all 15 ." After two years of con- 
tinuous work along the American shores he 
could still tell the same sympathetic cor- 
respondent: "I am quite charmed with 
geology, but like the wise animal between 
two bundles of hay, I do not know which to 
like best the old crystalline group of rocks 
or the softer and fossiliferous beds. When 
puzzling about stratification etc. I feel in- 
clined to cry, ' a fig for your big oysters and 
your bigger megatheriums.' But when dig- 
ging out some fine bones, I wonder how any 
man can tire his arms with hammering 
granite 16 ." 



14 CHARLES DARWIN 

How thoroughly he grew to be a field- 
geologist, never to be caught without his 
hammer, even when on botanical or zoological 
quests, is amusingly illustrated by his account 
of a visit to the island of San Pedro, north 
of the Chonos Archipelago off the southern 
part of the coast of Chile. Two of the 
officers of the ship had landed to take some 
bearings with the theodolite, while Darwin, 
hammer in hand, was rambling by himself. 
In the course of his perambulations, as he 
has told, "a fox (Canis fulvipes) of a kind 
said to be peculiar to the island and very 
rare in it, and which is a new species, was 
sitting on the rocks. He was so intently 
absorbed in watching the work of the officers 
that I was able by quietly walking up behind 
to knock him on the head with my geological 
hammer. This fox, more curious or more 
scientific, but less wise, than the generality 
of his brethren is now mounted in the Museum 
of the Zoological Society 17 ." 

While from time to time he was able to 
send home the collections that were accumu- 



AS GEOLOGIST 15 

lating in the Beagle, his notes of specimens 
and field-observations continued to grow in 
bulk. By the middle of the voyage, as he 
informed Henslow, they already filled some 
600 quarto pages of manuscript, of which 
about the half related to geology 18 . The 
perusal of the second and third volumes of 
the Principles of Geology, which had now 
been published and were sent out to him, 
increased his devotion to Lyellian views. He 
even remarks that he was inclined to carry 
some parts of the doctrine to a further length 
than the master himself 19 . 

It is not possible within the limits of a 
lecture to offer more than a mere sketch of 
the geological work which was accomplished 
by Darwin during the voyage. In four 
distinct departments he enriched the science 
with new and valuable material. In the first 
place he added to our knowledge of the 
volcanic history of the globe by many 
detailed observations extending over a vast 
geographical region. In the second place, 
he brought forward a body of striking evidence 



16 CHARLES DARWIN 

as to upward and downward movements 
of the terrestrial crust, and drew from this 
evidence some of the most impressive de- 
ductions to be found in the whole range of 
geological literature. In the third place, he 
made important observations on the geology 
of South America, from the crystalline cores 
of Brazil and the Andes to the Tertiary 
and Post-tertiary deposits of Patagonia. In 
the fourth place, he furnished new and inter- 
esting illustrations of the potent part taken 
by the denuding agents of nature in effecting 
the decay and degradation of the land. 

I. As we follow Darwin in his rambles 
over the volcanic tracts that were visited 
during the voyage of the Beagle, we cannot 
but be struck with the way in which he 
always seeks to unravel the sequence of 
events in the history of each centre of 
eruption. While the details of rock-structure 
and composition do not escape his notice, 
their interest for him was obviously much 
less than that of the chronicle of geological 
changes which the rocks revealed. How 



AS GEOLOGIST 17 

delighted he seems always to have been to 
trace in a volcanic island the successive 
phases from the early submarine eruptions 
to the completed subaerial volcano ! With 
what zeal he observes and records the occur- 
rence of layers of sea-shells and nests of salt 
and gypsum, intercalated between the more 
ancient lavas, as proofs of the uprise of the 
sea-floor! The pursuance of the later history 
of the volcano was a further source of keen 
pleasure to him, as he noted the positions of the 
earlier vents and the evidence of long intervals 
of quiescence between the successive out- 
bursts, when the mouldering lavas were 
hollowed out by running water into valleys 
and ravines, which eventually became the 
channels wherein the youngest streams of 
molten rock found their way to the sea. It 
was always these broader questions of geo- 
logical history that more especially appealed 
to his imagination and awakened his active 
interest. 

Throughout those years of travel he was 
ever on the outlook for fresh records of former 



18 CHARLES DARWIN 

igneous action. As the result of his continued 
observations he was able at last to sketch an 
impressive picture of the part which that 
form of geological agency has played in the 
construction of the framework of the South 
American continent. In his traverses of the 
Andes, under an atmosphere resplendently 
clear, and among steep mountain-sides rising 
up absolutely bare of vegetation, he could 
detect and follow the several great rock-groups 
out of which the giant chain of the Cordillera 
has been built. At the base he found a vast 
succession of andesitic lavas and conglome- 
rates, estimated by him to be some 7000 or 
8000 feet thick, which from the fossils he 
found associated with them, he assigned to 
the age of the early part of the Cretaceous 
period. Later in date came another copious 
volcanic series in which the lower lavas were 
believed by him to have been poured out 
under the sea, while the later eruptions were 
certainly subaerial, for he found a group of 
erect silicifled coniferous trees enclosed 
among the hardened volcanic ashes and 



AS GEOLOGIST 19 

surmounted by a massive canopy of basalt, 
1000 feet in thickness 20 . Younger still were 
the huge basaltic sheets which he traced 
among the Upper Tertiary formations of the 
Santa Cruz river, and last of all came the 
existing still active volcanoes of the Andes, 
which brought the long record of eruptions 
down to the present day. 

We may well believe that this marvellous 
chronicle of volcanic activity deeply impressed 
itself on Darwin's mind. It could not but 
give him a more vivid conviction of the 
potency of this branch of geological dynamics 
than most geologists have an opportunity of 
acquiring. Nevertheless it did not turn him 
into a convulsionist. Nor while his imagina- 
tion dwelt upon the grand succession of 
events which revealed itself to him step by 
step as the years went on, did he neglect the 
less exciting but not less necessary observa- 
tions of the lithological and other details that 
characterised the volcanic rocks. He was 
a diligent and judicious collector of rock- 
specimens, as his collections, still extant, 

22 



20 CHARLES DARWIN 

abundantly testify, and he studied them with 
such appliances as were then available for 
petrographical research. Besides the elabo- 
rate notes which he made of their characters 
in the field, he examined them with the blow- 
pipe, the goniometer, and the microscope, 
besides taking their specific gravity and 
applying to them the simpler chemical tests. 
His account of the bombs and the banded 
trachytes and obsidians of the island of 
Ascension has long taken its place as one of 
the classic descriptions of modern petro- 
graphy 21 . Still more remarkable was his 
prescient inference as to the separation of 
the basic from the acid constituents in large 
bosses of granite a suggestion which, after 
having been for many years lost sight of, 
has now been established as true 22 . His 
sagacious reflections upon the relations be- 
tween the cleavage and foliation of altered 
rocks were likewise far in advance of his 
time 23 . 

II. The long series of observations and 
deductions made by Darwin on the move- 



AS GEOLOGIST 21 

ments of the crust of the earth, both in an 
upward and downward direction, have long 
held an honoured place in the literature of 
physical geology. He was the first observer 
who could devote himself to this department 
of investigation by personal research and 
comparison over a vast area of the surface of 
the globe, and could thus generalise in it upon 
a basis of his own experience in the field. 
During the very first halt of the Beagle at 
the Cape de Verde Islands, his attention was 
drawn to this subject of enquiry by the 
evidence of upheaval which he met with at 
St Jago. All through the successive years 
of the voyage he continued to accumulate 
facts, until they grew into such an array of 
evidence as no previous geologist had ever 
been able to amass. Especially important 
were the proofs which he collected of the 
rise of the southern part of South America. 
From the shores of Brazil and Uruguay, where 
the youngest marks of uplift are found only 
a few feet above sea-level, he traced a mag- 
nificent succession of terraces that spread 



22 CHARLES DARWIN 

over the broad tract of lowland between the 
mountains and the Atlantic, and stretch 
southwards for hundreds of miles to the 
southern bounds of Patagonia. At least 
eight of these terraces were noted by him, 
each flanked with a bold line of winding 
escarpment that fronted the coast-line and 
slowly mounted as they were followed south- 
wards, one above another, up to heights of 
950 or even 1200 feet. The occurrence of 
recent marine shells on at least the lower 
platforms led him to the conclusion that the 
uplift of this part of the continent must have 
been a comparatively late geological event. 
From the step-like series of terraces he in- 
ferred that the elevation took place inter- 
mittently, with long pauses of rest, during 
which the sea cut back the successive fronts 
of these ancient inland-cliffs, as it is doing 
still along the present coast-line. From the 
greater height of the terraces in southern 
Patagonia, he drew the deduction that the 
uprise of the continent has been greatest 
towards the south, and has gradually and 



AS GEOLOGIST 23 

imperceptibly diminished in a northerly 
direction 24 . 

Similar evidence of the recent uprise of 
the continent was obtained by Darwin on 
the western coast at various places between 
lat. 4635' and 12S. a distance of more than 
2000 geographical miles. The nearness of 
the mountain chain to the Pacific Ocean has 
not allowed the formation of any such display 
of broad platforms at successive levels, as in 
Patagonia. But he gathered conclusive proofs 
of uplift, not only in raised beaches with 
recent marine shells, but in abundant marks 
of old sea-margins at different levels, such 
as sea-worn caves, barnacle-crusted rocks, 
pholades still in their positions of growth, 
and successive gravel-terraces. The greatest 
height at which he was able to detect recent 
species of marine organisms was 1300 feet 
above the sea at Valparaiso 25 . 

As his acquaintance grew with the records 
of the geological history of South America, 
Darwin became more and more impressed 
by the proofs he obtained of the remarkable 



24 CHARLES DARWIN 

oscillations of level which the continent has 
undergone from the earliest times down to 
our own day. Reflecting on what he had 
seen on his traverses of the Cordillera and in 
Patagonia, he made this deliberate state- 
ment : " Daily it is forced home on the mind 
of the geologist that nothing, not even the 
wind that blows, is so unstable as the crust of 
the earth 26 ." 

It so happened that Darwin was ashore at 
Valdivia on the day of the great earthquake 
in February 1835, and felt the shock. A few 
days later the Beagle entered the harbour of 
Concepcion where, amidst a city of ruins, he 
came upon what he describes as "the most 
awful yet interesting spectacle he had ever 
beheld." He has recorded that from a 
geological point of view, "the most remark- 
able effect of this earthquake was the per- 
manent elevation of the land," but he adds 
that instead of saying the effect, "it would 
probably be far more correct to speak of it 
as the cause 27 ." He was satisfied that the 
land around the bay had been upraised two 



A8 GEOLOGIST 25 

or three feet, while on an island about thirty 
miles off, Captain Fitzroy had found putrid 
mussel-shells still adhering to the rocks ten 
feet above high-water mark, where the in- 
habitants had previously dived at low-water 
spring-tides for these shells. He connected 
this result of the earthquake with the general 
rise of the whole continent, regarding it as a 
kind of sample of the process whereby the 
uplift had been brought about. As he re- 
marked in his Journal : " it is hardly possible 
to doubt that this great elevation has been 
effected by successive small upliftings, such 
as that which accompanied or caused the 
earthquake of this year, and likewise by an 
insensibly slow rise, which is certainly in 
progress on some parts of this coast 28 ." As 
his generalisation on the whole subject, he 
held that " thousands of miles of both coasts 
of South America have been upraised within 
the recent period by a slow, long-continued, 
intermittent, movement 29 ." 

This impressive conclusion, as the final 
outcome of his long years of investigation, 



26 CHARLES DARWIN 

was accepted by geologists and was incor- 
porated by them into their common stock of 
ascertained knowledge. Some years ago, 
however, its validity was called in question. 
The illustrious president of the Vienna 
Academy of Sciences, Professor Suess, in the 
series of striking pictures which he has drawn 
of the changes which the surface of the earth 
has undergone, and of the causes to which 
these revolutions are to be ascribed, has 
referred to Darwin's observations, which he 
has somewhat summarily rejected as inad- 
missible. He has been led, I think, by his 
strong theoretical prepossessions against any 
kind of evidence for the secular elevation of 
continental areas of land, to minimise and 
explain away the proofs adduced by Darwin. 
He has availed himself of any expression of 
doubt or denial made by one or two later 
writers, which he accepts as well-founded. 
The testimony alleged to be borne by the 
terraces to the uprise of the land he briefly 
sets aside, with the suggestion that they may 
often be relics of the action of rivers or 



AS GEOLOGIST 27 

lakes. The recent marine shells found inland 
he looks upon as having been carried by 
the inhabitants and to be counterparts of 
the familiar kitchen-middens of European 
coasts 30 . 

Charles Darwin was not a careless or casual 
observer, nor one who rapidly jumped to a 
conclusion from a limited basis of proof. He 
was in the constant habit of repeating his 
observations and checking his deductions, 
and he had ample opportunities of doing so 
in the geological field during the years that 
he spent in South America. He was surely 
competent to discriminate between platforms 
extending for hundreds of miles parallel to 
the coast-line, and terraces limited to each 
river-system or to lakes. He was perfectly 
familiar with the custom of the natives to 
transport edible shell-fish for long distances 
into the interior, and actually alludes to this 
habit when describing deposits which he 
believed to be true raised beaches 31 . He 
was consequently on his guard against being 
deceived by artificial accumulations of shells, 



28 CHARLES DARWIN 

and he gives the criteria by which he dis- 
criminated between them and natural deposits 
criteria which any field-geologist would 
accept as sufficient. 

Until therefore the evidence has been 
sifted on the ground by a witness as capable 
and as unbiassed as Darwin himself, I shall 
continue to retain my belief in the trustworthi- 
ness and importance of the observations and 
conclusions of the great naturalist as to the 
upheaval of those parts of South America 
which he had himself the opportunity of ex- 
amining. His contributions to this subject 
have long been prized by geologists for their 
fullness and clearness, and for their interest 
and value in relation to the great problem 
of the secular elevation of land. He himself 
had no doubt that they were solid additions 
to geological science, and such, I venture to 
anticipate, will be the judgment of posterity. 

After the close of the voyage of the 
Beagle, when Darwin had found time to 
study his collections and to reflect upon his 
varied experiences of geological phenomena 



AS GEOLOGIST 29 

during five busy years, he put in writing the 
matured opinions which he had formed on 
the forces concerned in continental elevation. 
His ample discussion of this subject, com- 
municated to the Geological Society on 
March 7th, 1838, forms one of the most 
brilliant and suggestive essays which that 
Society ever published 32 . Although the pro- 
gress of investigation has not sustained some 
important parts of his theoretical opinions 
on this subject, it is impossible to read his 
memoir without a high admiration for the 
genius of its author. Marshalling all the 
evidence then available, he arranges it in 
logical sequence and deduces from it con- 
clusions of profound interest in regard to 
some of the obscurest problems in the history 
of our globe. It was the first attempt to 
treat this subject not as a mere matter of 
idle speculation, but on a basis of personal 
observation in the field. And thus, as a 
pioneering effort it is worthy of lasting re- 
cognition. 

We can readily understand how he should 



30 CHARLES DARWIN 

have been led to adopt the views promulgated 
in this remarkable paper. He had himself 
witnessed a severe earthquake, and could 
speak from personal knowledge of its effects 
in a region which had often been convulsed 
by similar events. He had found that one 
of these effects was a marked uplift of some 
parts of the coast-line. He had beheld with 
his own eyes the simultaneous and violent 
activity of two of the great volcanoes of 
the Cordillera 33 . Pondering on these mighty 
manifestations of terrestrial energy, and re- 
membering what a long succession of volcanic 
periods he had detected in the framework 
of the continent, he conceived not only that 
earthquakes and volcanoes are intimately 
related to each other, as was then generally 
believed, but that they both proceed from 
movements in the internal molten material 
of the globe. Although the origin of these 
movements was shrouded from him, he be- 
came convinced, to use his own impressive 
words, that "the configuration of the fluid 
surface of the earth's nucleus is subject to 



AS GEOLOGIST 31 

some change its cause completely unknown, 
its action slow, intermittent, but irresistible 34 ." 
These theoretical views seemed at the time 
to be warranted by all the evidence which 
had then been obtained on the subject, and 
more especially by the large body of proof 
which the author himself had gathered to- 
gether. But the extended researches of later 
years in seismology and mountain-building 
have brought to light much information which 
he did not possess. We now know that there 
is no such general and intimate relation, as 
was then assumed, between earthquakes and 
volcanoes; for many gigantic earthquakes 
have taken their origin at a distance from 
active volcanoes, while vigorous volcanic 
energy is not always accompanied with earth- 
quakes or with permanent alterations in the 
relative levels of sea and land. Since his 
time, too, the complicated structure of 
mountain-chains has been elucidated in much 
detail. We have learnt how intensely, along 
these tracts of elevated ground, the terrestrial 
crust has been folded, crumpled, fractured 



32 CHARLES DARWIN 

and piled upon itself, without any sign of con- 
comitant and co-operating volcanic agency. 
But in regard to the cause of the secular up- 
lift of continental land, we are still as ignorant 
as Darwin confessed himself to be. It is 
quite conceivable that for this phenomenon 
his suggestion respecting movements of the 
molten nucleus of the planet may, in some 
form, come to be eventually established. 

Besides meditating on the evidence in 
favour of the elevation of land, Darwin during 
his life in the Beagle had occasion to 
consider terrestrial movements of an opposite 
kind. It was during those eventful years 
that he thought out his famous theory of 
coral-reefs which gave to the world the most 
original and impressive picture ever drawn 
of the slow disappearance of an ancient land- 
surface beneath the sea. The origin of these 
singular islands, rising out of the profound 
depths of mid-ocean, had long been a subject 
of discussion, and several explanations of 
them had been proposed, more or less plausi- 
ble, but not free from objections. Darwin 



A8 GEOLOGIST 33 

offered a new suggestion which appeared to re- 
move all the difficulties that were then known. 
He showed how on the simple hypothesis of 
a slow subsidence of the bed of the ocean, 
fringing-reefs of coral along a coast-line could 
be converted into barrier-reefs with a lagoon- 
channel between them and the shore, and 
further, how, where the land was insular and 
continued to sink along with the surrounding 
sea-floor, while at the same time the polypifers, 
in their accumulation of calcareous material, 
kept pace with the downward movement, the 
barrier-reef would become an atoll or ring 
of coral-rock enclosing a lagoon beneath which 
the last peak of land might in the end dis- 
appear. With admirable clearness he worked 
out the application of this theory to all the 
facts that were then known about the struc- 
ture and distribution of coral-reefs, and he 
came to the conclusion that over vast spaces 
of the Pacific and Indian Oceans former tracts 
of land have slowly sunk beneath the water, 
and that the sites of the submerged peaks 

G. 3 



34 CHARLES DARWIN 

are to be recognised in the countless groups 
and archipelagoes of coral-islands 35 . 

The remarkable simplicity of this expla- 
nation of phenomena that had so long been 
matters of dispute, together with the grandeur 
of the vista which the theory opened up of a 
stupendous geographical revolution that had 
been in progress since a remote antiquity, 
assured Darwin's views of close attention 
and led to their general acceptance. First 
brought briefly before the Geological Society 
in 1837, and expounded more fully five years 
later in his well-known volume on coral-reefs, 
the theory held its place unchallenged for 
many years. Louis Agassiz had indeed in- 
sisted that it could not be applied to the 
coral-reefs of Florida, but not until 1863 were 
serious doubts thrown on its general appli- 
cability, when Professor Semper brought 
forward evidence of elevation among the 
Pelew Islands. In a second edition of his 
book, which appeared in 1874, Darwin briefly 
referred to this new evidence, but did not 
regard it as incompatible with his views. In 



AS GEOLOGIST 35 

later years, however, the observations which 
have multiplied over many widely distributed 
parts of the Pacific and Indian Oceans, as 
well as in the warmer waters of the Western 
Atlantic, have supplied a large body of proof 
that in many groups of coral-islands the 
movement of the sea-bottom has been up- 
ward, the amount of elevation amounting in 
some cases to more than 1000 feet. The 
conclusion reached by such observers as Sir 
John Murray, Professor Alexander Agassiz, 
Dr H. B. Guppy and others is that true 
atolls may be formed without subsidence, 
by the outward growth of the coral upon a 
talus of debris torn from the face of the reefs 
by the force of the breakers. These writers, 
who have carefully studied the subject on 
the ground, have come to the conclusion that 
Darwin's explanation cannot be maintained 
as of universal application. After the fullest 
consideration I have been compelled to 
admit that this conclusion is well founded. 
There can, I think, be no doubt that Darwin's 
simple and striking explanation would per- 

32 



36 CHARLES DARWIN 

fectly account for the origin of a great many 
atolls. It remains to be seen whether, and 
how far, it may be possible eventually to dis- 
criminate between those which are to be thus 
understood from those where the coral-site 
has remained stationary or has been upraised. 
But the mere existence of an atoll can no 
longer be regarded as in itself a proof of 
subsidence. It has been to myself and to 
many other geologists a matter of keen regret 
that this brilliant generalisation of the great 
naturalist has been deprived of the wide 
application which for many years we attri- 
buted to it. But while we bow to the results 
of later investigation, we must still be allowed 
to regard it as a monument of his genius, 
which did good service by lifting geological 
speculation to a higher plane, and filling our 
minds with a more vivid conception of the 
gigantic scale on which the movements of 
the terrestrial crust may have been effected. 
III. An important part of the solid 
work accomplished by Darwin during his 
life in the Beagle is to be found in his 



A8 GEOLOGIST 37 

numerous contributions to the elucidation 
of South American geology. It would be 
out of place to attempt to enumerate on 
this occasion these various additions to our 
knowledge of the subject. I have already 
alluded to his studies of the older crystalline 
rocks of that continent, to his sagacious con- 
clusions regarding the connection between 
cleavage and foliation which he drew from 
these rocks, and to his far-sighted remarks 
on the segregation of the more basic from 
the acid constituents of eruptive bosses of 
granite which he traced in Brazil. His tra- 
verses of the chain of the Andes enabled him 
to furnish an interesting sketch of the general 
architecture of that great range of mountains. 
He fixed, from the evidence of associated 
fossils, the geological age of the vast igneous 
protrusions which form the core of the Cor- 
dillera. His researches in Patagonia led the 
way in the investigation of the great Tertiary 
series in that extensive territory. To his 
enthusiastic labours we owe the important 
palaeontological discoveries which for the first 



38 CHARLES DARWIN 

time revealed the extraordinary abundance 
and variety of the extinct vertebrate remains 
in the youngest deposits of that region. Owen 
in the Preface to his Memoir descriptive of 
the series of fossils exhumed by Darwin, 
speaks of the collection having been made 
by one individual from a comparatively small 
part of South America, and remarks that 
"the future traveller may fairly hope for 
similar success, if he bring to the search 
the same zeal and tact which distinguish the 
gentleman to whom Oryctological Science is 
indebted for such novel and valuable ac- 
cessions 36 ." 

IV. The voyage of the Beagle, with its 
ample opportunities on land as well as on 
sea, gave Darwin many occasions to study 
the great system of agencies which are cease- 
lessly at work in sculpturing the face of 
the land. He probably gained such a vivid 
personal acquaintance with this subject as 
few, if any, of the geologists of his day had 
an opportunity of acquiring. This first-hand 
knowledge stood him in good stead when in 



A8 GEOLOGIST 39 

later years he had to deal with questions of 
geological time. It enabled him also to lend 
a powerful support to the views of Lyell and 
the cause of uniformitarianism against cata- 
strophism. 

The deep impression made on his mind 
by the examples of stupendous denudation 
which came before him in South America, 
finds frequent mention in his writings. In 
this regard, the chain of the Cordillera more 
particularly roused his enthusiastic appre- 
ciation. "This grand range," he remarks, 
"has suffered both the most violent disloca- 
tions and slow, though grand, upward and 
downward movements in mass. I know not 
whether the spectacle of its immense valleys 
with mountain masses of once-liquefied and 
intrusive rocks, now bared and intersected, 
or whether the view of those plains, composed 
of shingle and sediment hence derived, which 
stretch to the borders of the Atlantic Ocean, 
is best adapted to excite our astonishment 
at the amount of wear and tear which these 
mountains have undergone 37 ." 



40 CHARLES DARWIN 

In the earlier part of his geological career, 
like his great teacher Lyell, he was disposed 
to credit the sea with a larger share than is 
now generally believed to be its due in the 
sculpture of the land. Nor need this be, in 
his case, matter of surprise, for he had made 
intimate personal acquaintance with the sea 
alike in calm and in storm. He had seen 
many striking instances of the efficacy of 
breakers in the erosion of coast-clifls. When 
he visited St Helena and gazed on its range 
of precipices rising here and there 1000 or 
even 2000 feet above the waves that burst 
into foam at their base, he felt that "the 
swell of the Atlantic Ocean has obviously 
been the active power in forming these cliffs." 
Again as he sailed along the coast of Pata- 
gonia and traced its successive escarpments 
that front the sea, one above another, for so 
many hundreds of miles, he could not but be 
impressed with the efficacy of marine action 
in the denudation of that wide region. When 
he found himself among the deep and wide 
valleys of the Blue Mountains in New South 



AS GEOLOGIST 41 

Wales, with their surrounding escarpment- 
cliffs, it was to the action of the sea that his 
thoughts naturally adverted as the cause of 
such a magnificent series of excavations. 
Like most of the geologists of the day he was 
convinced that " to attribute these hollows to 
alluvial action would be preposterous 39 ." 

Yet he was far from insensible to the 
results of the long-continued operation of sub- 
aerial agents in changing the face of the land. 
In his Journal he has recorded in graphic 
language the lesson on the erosive power 
of rivers which was graven on his memory by 
what he saw when he crossed the Andes by 
the Portillo Pass. As he watched the 
torrents, brown with mud, rushing headlong 
down the valleys and sweeping onwards the 
stones on their channels with a roar which 
could be heard at a distance, like the tumult 
of the sea in a storm, he realised how "the 
sound spoke eloquently to the geologist ; the 
thousands and thousands of stones which, 
striking against each other, made the one 
dull uniform sound, were all hurrying in one 



42 CHARLES DARWIN 

direction. It was like thinking on time, where 
the minute that now glides past is irrecover- 
able. So was it with these stones; the ocean 
is their eternity, and each note of that wild 
music told of one more step towards their 
destiny. It is not possible," he continues, 
"for the mind to comprehend except by a 
slow process, any effect produced by a cause 
repeated so often that the multiplier itself 
conveys an idea not more definite than the 
savage implies when he points to the hairs of 
his head. As often as I have seen beds of 
mud, sand and shingle, accumulated to the 
thickness of many thousand feet, I have felt 
inclined to exclaim that causes such as the 
present rivers and the present beaches could 
never have ground down and produced such 
masses. But, on the other hand, when listen- 
ing to the rattling noise of these torrents, and 
calling to mind that whole races of animals 
have passed away from the face of the earth, 
and that during this whole period, night and 
day, these stones have gone rattling onward 
on their course, I have thought to myself can 



A8 GEOLOGIST 43 

any mountains, any continent withstand such 
waste 40 ." 

After an absence of almost five years the 
Beagle came back to England in October, 
1836. That in spite of all the biological 
questions which during the voyage had 
shaped themselves before him and had en- 
gaged his keenest interest, Darwin still 
retained his early enthusiasm for geology is 
well shown in his records of the vessel's 
homeward journey which filled the fifth year 
of the expedition. It was during that year 
that he saw Tahiti, and touched at New 
Zealand, Sydney and Tasmania, everywhere 
adding fresh geological material to his note- 
books. It was then, too, that he crossed the 
Indian Ocean and had an opportunity of 
making his study of coral-reefs which led to 
his generalisation about oceanic subsidence. 
On the same section of the voyage he again 
traversed the Atlantic twice, halting at St 
Helena and Ascension on the way, and once 
more landing at the Cape de Verde Islands as 



44 CHARLES DARWIN 

the vessel finally shaped her course towards 
home. His letters show how eagerly, as each 
chance presented itself, to use his own words, 
he "set to work with a good will at my old 
work of geology 41 ." From St Helena he 
wrote to Henslow that he was " very anxious 
to belong to the Geological Society 42 ." This 
desire was speedily fulfilled. His work on 
the Beagle had become widely known by the 
publication of excerpts from his letters to 
Henslow. His scientific reputation had con- 
sequently been so well established that not 
only was he elected into the Society at the 
beginning of the session in November, a few 
weeks after his return, but in the following 
February he was chosen as one of the Council, 
and a year later (1838) was persuaded to 
accept one of the two secretaryships an 
office which he held for three years. 

He was now at the very centre of geo- 
logical activity, surrounded with colleagues 
whose names and work have given to that 
heroic age of geology in this country an 
imperishable lustre. To be associated with 



AS GEOLOGIST 45 

such leaders as Lyell, Sedgwick, Murchison, 
Greenough, Buckland, Fitton, De la Beche, 
Whewell and Owen could hardly fail to fan 
the flame of Darwin's geological proclivities. 
That he was appreciated and welcomed by 
these magnates in the science is testified in 
a hearty way by Lyell who wrote to Sedgwick 
(21st April, 1837): "It is rare even in one's 
own pursuits to meet with congenial souls; 
and Darwin is a glorious addition to my 
society of geologists, and is working hard 
and making way both in his book and in our 
discussions. I really never saw that bore - 
so successfully silenced, or such a bucket of 
cold water so dexterously poured down his 
back as when Darwin answered some imper- 
tinent and irrelevant questions about South 
America 43 ." 

For some years most of Darwin's time 
was necessarily occupied in working up and 
publishing the voluminous material accu- 
mulated during his travels. Some of this 
material he prepared in the form of papers 
communicated to the Geological Society, 



46 CHARLES DARWIN 

notably the great memoir, already alluded to, 
on the Connection of Volcanoes and Earth- 
quakes. But he found time also for some 
fresh geological work in this country, more 
particularly in regard to certain later phases 
in the evolution of the present features 
of the surface of the land. Thus in one of 
these enquiries he was led to visit the Parallel 
Roads of Glen Roy and to write a memoir 
upon them wherein he advocated their marine 
origin 44 . Somewhat later he made an excur- 
sion into the district of North Wales over 
which Sedgwick had taken him eleven years 
before. But in the interval the attention 
of British geologists had been roused by 
Agassiz to the proofs that their own country, 
at a comparatively late geological period, 
was buried under snow and ice. Darwin may 
have been led to return to Caernarvonshire 
by some vague recollection of topographical 
features in that region which were not 
specially noted by him at the time. He has 
recorded that neither Sedgwick nor he " saw 
a trace of the wonderful glacial phenomena 



A8 GEOLOGIST 47 

all around us. Yet these are so conspicuous 
that a house burnt down by fire did not tell 
its story more plainly than did this valley. 
If it had been still filled by a glacier, the 
phenomena would have been less distinct 
than they now are 45 ." The paper in which 
he described his observations in this Welsh 
valley was one of the earliest in the volumi- 
nous literature that has now gathered round 
the subject of the glaciation of the British 
Isles 46 . 

For some twenty years after his return 
from the voyage of the Beagle Darwin con- 
tinued to write occasional geological papers, 
especially in relation to glacial matters, the 
last of them being published so late as 1855 47 . 
Of all these contributions to geology the 
most original and important was a brief 
paper on the formation of vegetable soil, 
which he communicated to the Geological 
Society in the autumn of 183T 48 . The 
youngest or surface layer of the earth's crust 
had for many years been strangely neglected 
by geologists. They had lost sight of the 



48 CHARLES DARWIN 

pregnant reference to it made at the begin- 
ning of last century by Playfair. That 
far-seeing writer, following up the earlier 
ideas of Hutton, had pointed out how con- 
tinually the surface soil is washed off the 
land and how it is as constantly renewed by 
the decay of organic and inorganic materials. 
But though he clearly recognised the reality 
and importance of this process of waste and 
renewal, he did not perceive the operation of 
perhaps the most important agency con- 
cerned in its efficiency. This discovery was 
first made known by Charles Darwin 49 . 

In the course of one of his visits to Maer 
Hall, his uncle, Josiah Wedgwood, called 
Darwin's attention to the curious way in which 
layers of cinders, burnt marl or lime, spread 
on the surface of pasture lands, eventually dis- 
appear under the grass, and at the same time 
suggested that this disappearance appeared to 
be due to the action of earth-worms in bring- 
ing up the finer particles of earth from below 
and leaving them on the surface. Darwin 
was naturally much interested in a subject so 



A8 GEOLOGIST 49 

obviously both geological and biological. 
With his characteristic patience and care he 
made a series of diggings, and soon satisfied 
himself as to the facts to be accounted for. 
He found that in one case a layer of marl, 
spread over a field of pasture, had in about 
80 years sunk some twelve or fourteen inches 
beneath the surface. He came to the con- 
clusion that this apparent subsidence had 
undoubtedly been due to the continued 
action of the worms, which after swallowing 
and digesting the finer portions of the soil, 
carry it up to the surface and void it there in 
their castings. He drew the striking deduc- 
tion that "every particle of earth forming the 
bed from which the turf in old pasture-lands 
springs has passed through the intestines of 



worms." 



Trifling as the topic may seem, and brief 
as was the announcement of it (for the paper 
filled only some four pages), the observations 
published by Darwin were eventually seen to 
possess a high importance in reference to 
the problems of land-sculpture. But these 



o. 



50 CHARLES DARWIN 

problems did not at that time, nor for many 
years afterwards, engage much attention. It 
was only when they began to be seriously 
discussed, and when the evidence was accumu- 
lating that the carving out of the face of the 
land had not been in great measure the work 
of the sea, as was so long believed, but was 
mainly due to subaerial agencies, as Hutton 
and Playfair had maintained, that the wide 
significance of Darwin's little paper was per- 
ceived. It was then realised that even grass- 
covered lands, screened as they seemed 
effectually to be by their vegetable covering, 
were nevertheless not exempt from the general 
process of degradation, for it was manifest 
that by the work of worms an appreciable 
quantity of soil, brought up to the surface 
every year, was there exposed to be washed 
off by rain or to be dried and blown away by 
wind. Thus level prairies and verdurous 
slopes were seen to be no exception to the 
operation of the universal ablation of the 
land. 

Although Darwin's original observations 



AS GEOLOGIST 51 

on this curious and important subject re- 
mained, as it were, buried in the publications 
of a scientific Society, he never lost his 
interest in it. As he wrote to Professor 
Carus, "it had been to him a hobby-horse." 
He was accustomed to keep worms in pots, 
for the purpose of studying their habits, and 
eventually he was led to renew and extend 
the observations contained in his early paper. 
He attacked the problem in much greater 
detail than before, including, as part of his 
labour, minute investigations of the habits 
and mode of action of the worms. He like- 
wise obtained more precise data by carefully 
measuring and weighing all the worm-castings 
thrown up within a given time in a measured 
space. The results of these patient enquiries 
were comprised in his well-known volume on 
Vegetable Mould 50 . 

It is interesting to remember that in this, 
his last published work, he returned once 
more to geological studies. But he now 
brought to their prosecution a wealth of 
biological experience and an ingeniously 

42 



52 CHARLES DARWIN 

devised system of measurement which gave 
to his results a precision not always attain- 
able in experimental geology. His volume 
thus holds an altogether unique place among 
modern contributions to the problems of 
denudation. It shows no lessening in his 
marvellous patience, his scrupulous aim at 
accuracy and his masterly power of rising 
from the minutest details into the broadest 
generalisations. Geologists may well regard 
this final volume as a legacy and example 
to them. 

I now come to consider in the last place 
the geological side of Darwin's masterpiece 
The Origin of Species. This great work, the 
outcome of his life-long researches and re- 
flections, could not but contain frequent 
reference to geological evidence which he 
had himself gathered from so wide a field, 
which he had pondered over so deeply, and 
which was so intertwined with all his other 
scientific work. We may compare his volume 
to a great symphony in which the chords 



AS GEOLOGIST 53 

from the various departments of biology are 
blended into one vast harmony, but where 
the deep under-tones of geology seldom fail 
to be audible. 

From the days of Buffon the problems 
presented by the question of the geographical 
distribution of plants and animals have 
engaged the thoughts of many naturalists and 
travellers. But not until the appearance of 
Lyell's Principles were the geological aspects 
of the subject systematically discussed. The 
chapters in the second volume of that work, 
wherein the phenomena of geographical dis- 
tribution were shown to have so close a 
connection with geological changes, must have 
been diligently perused by Darwin on the 
voyage of the Beagle. We may believe, in- 
deed, that it was in no small measure from 
their broad philosophical treatment and their 
suggestiveness to him in his own researches, 
that he conceived that deep respect and admi- 
ration for Lyell, to whom he was always proud 
to acknowledge his indebtedness. Darwin's 
two chapters on Geographical Distribution 



54 CHARLES DARWIN 

bear the characteristic impress of that wide 
biological and geological experience which 
gave him so firm a mastery of the points to 
be discussed. They display his candid fair- 
ness in stating difficulties, together with his 
earnest desire not to minimise or ignore them, 
his caution and even diffidence in offering his 
own suggestions for their solution, and his 
power of luminous presentation wherewith he 
could place the whole complicated subject in 
coherent, intelligible arid interesting form. 
The progress of geology since Lyell's early 
days enabled him to trace more definitely the 
effects of geographical changes for which there 
is reasonable evidence. Thus he attached 
much importance to the direct and indirect 
influence of the Glacial Period in reference 
to the dispersal of plants and animals. His 
treatment of this subject fills some of the 
most striking pages of his volume. The reader 
is made to realise, as he may never have done 
before, that each species has had a long 
geological history, which in many cases throws 
light on the geographical revolutions that 



AS GEOLOGIST 55 

preceded or accompanied the advent of 
man. 

But with his cautious temperament he 
could find no favour for the bold hypotheses 
of some naturalists who, in default of other 
means of accounting for the present distribu- 
tion of living organisms, have not scrupled to 
invoke the most gigantic changes in the 
disposition of sea and land, for which, how- 
ever, no geological evidence can be adduced. 
" I do not believe," he affirmed, " that it will 
ever be proved that within the recent period 
most of our continents, which now stand quite 
separate, have been continuously, or almost 
continuously, united with each other and 
with the many existing oceanic islands 51 ." 
He was content with less heroic methods of 
interpretation, and relied on such means of 
dispersal as can be seen to be effective in the 
present geographical condition of our globe. 

The two specially geological chapters in 
the Origin of Species have always seemed to 
me to form Darwin's most momentous con- 
tribution to the philosophy of geology. I 



56 CHARLES DARWIN 

well remember the effect which, when they 
first appeared, they produced on at least the 
younger geologists of the day. The fact that 
the Geological Record is far from complete 
was, of course, familiar knowledge. But until 
these two chapters revealed it with such full- 
ness of detail and such force of argument, 
I do not believe that any one of us had the 
remotest conception that the extent of its 
imperfection was so infinitely greater than 
we had ever imagined. The idea of pro- 
gressive organic development was then in 
general disfavour, and so long as that was 
the case, the blanks in the Geological Record 
lost much of their interest and importance 
as indications of chronometric intervals. 
Lyell, from the appearance of the first edition 
of his Principles of Geology had consistently 
maintained his determined opposition to all 
doctrines involving the mutability of species. 
In his ninth edition which, in an "entirely 
revised" form, appeared in 1853, he could 
still write: "the views which I proposed in 
the first edition of this work, January 1830, 



AS GEOLOGIST 57 

in opposition to the theory of progressive 
development do not seem to me to require 
material modification, notwithstanding the 
large additions since made to our know- 
ledge of fossil remains 52 ." What he had been 
inculcating for nearly a quarter of a century 
had become the accepted belief of the great 
body of geologists in this country, even of 
those who dissented most strongly from his 
uniformitarianism. 

Yet there were some among them who 
found it hard to follow their great leader in 
this part of his teaching. He seemed to 
them to undervalue the evidence that ap- 
peared so plainly to indicate that there has 
been an ordered upward succession in the 
appearance of the several divisions of the 
animal and vegetable worlds. When he 
declared that the occurrence of the remains 
of fishes in the groups of strata below the 
Coal formation " entirely destroys the theory 
of the precedence of the simplest forms of 
animals 53 ;" when he suggested that the non- 
occurrence of mammalian remains among the 



58 CHARLES DARWIN 

older rocks might be merely due to the 
imperfect state of our information 54 , and when, 
in explanation of the poverty of the records 
of the floras and faunas of the past, he offered 
the consolation "that it has evidently been 
no part of the plan of Nature to hand down 
to us a complete or systematic record of the 
former history of the animate world," an un- 
easy conviction grew up that the testimony 
of the rocks could not thus be set aside. 
Vehemently insisting on "the doctrine of 
absolute uniformity" in geological causation 55 , 
Lyell could account for the extinction of the 
thousands of species of organisms that once 
lived on the earth by reference to the normal 
laws of nature, as seen in the operation of 
the various causes that are still at work. 
But when he contemplated the thousands of 
new species which have successively replaced 
those that died out or were destroyed, he 
had recourse to a special act of creation for 
each of them, thus appealing to an agency 
whose working, while it might be in conson- 
ance with natural law, lies outside of human 



AS GEOLOGIST 59 

experience. His deliberate judgment was 
formulated in the following words: "Each 
species may have had its origin in a single 
pair, or individual where an individual was 
sufficient, and species may have been created 
in succession at such times and in such 
places as to enable them to multiply and 
endure for an appointed period, and occupy 
an appointed space on the globe 56 ." 

It is well to recall these aspects of geo- 
logical thought in the middle of last century, 
and to remember what a dead weight of 
opinion, or, if we choose to call it prejudice, 
was opposed to the reception of Darwin's 
views. We must bear in mind also that the 
leader of this school of thought was none 
other than his own revered master Lyell, at 
whose feet he had sat for so many years and 
to whom he felt that he owed more inspira- 
tion than to any other man. Lyell, who had 
all his life opposed the idea of the mutation 
of species, was slow to be completely con- 
vinced of the truth of the conclusions at 
which his friend and follower had arrived. 



60 CHARLES DARWIN 

In the volume on the Antiquity of Man which 
he published four years after the appearance 
of the Origin of Species he hesitatingly and 
v only partially accepted them 57 . In the course 
of a few years more his conversion was com- 
plete, as he announced in the tenth and last 
edition of his Principles of Geology. 

Lyell's courageous abandonment of opin- 
ions which he had stoutly proclaimed through 
a long life was a noble example of self- 
abnegation in the cause of truth. It did 
good service in helping forward the general 
acceptance of the newer creed, and it was 
especially appreciated by the younger geolo- 
gists. Among their number were not a few 
who felt when they read the Origin of Species, 
that truly the scales had now fallen from 
their eyes. There had been with them a 
conviction that the grand progression of 
organic life, from the earliest time until now, 
must somehow have been governed by normal 
biological law, though no satisfactory ex- 
planation had been offered of the manner 
in which this continuous upward progress 



AS GEOLOGIST 61 

had been achieved. Darwin's treatment of 
the subject fascinated them by the genius 
with which his long and varied experience 
abroad and at home, alike in the geological 
and biological domains, was brought to bear 
on the elucidation of the great problem of 
evolution for which he had so amply prepared 
himself. Especially were they struck with his 
mastery of the whole range of stratigraphy. 
Into that department of geology he threw 
a flood of new light, as for example when he 
so cogently urged that complete conforma- 
bility, or absence of visible break, may be no 
proof of continuous deposition, but may con- 
ceal protracted periods of time unrepresented 
by strata. Yet even where his arguments 
were most forcible and convincing, they were 
stated without the least show of dogmatism, 
but with a quiet restraint that was apt to 
conceal their strength. As we read them 
now, they seem to be so obvious that it may 
be wondered why they were not pressed long 
before. Not only did he convince us of the 
unsuspected degree of imperfection in the 



. 



62 CHARLES DARWIN 

Geological Record, but he revealed a new 
method of interpreting it by showing that, on 
the theory of descent with modification, fossils 
possess a high chronometric value as in- 
dicative of the relative importance of strati- 
graphical horizons and likewise a new sugges- 
tiveness in regard to geographical changes of 
which no other memorial may have survived. 
The light thrown by Darwin upon the 
fossiliferous formations of the earth's crust 
led to clearer conceptions of the principles 
that must be applied to the interpretation 
of the facts of stratigraphy. The sudden 
appearance of whole groups of new species 
upon a special stratigraphical platform, had 
once been confidently appealed to as evidence 
of a fresh creation of plants and animals to 
replace those which were destroyed by a catas- 
trophe that convulsed the world. This opinion, 
though no longer expressed in the crude 
shape in which such writers as Cuvier had 
announced it 58 , still in a modified form in- 
fluenced many naturalists and geologists who, 
though not convulsionists, were opposed to 



AS GEOLOGIST 63 

the idea of the transmutation of species. 
Darwin's cogent reasoning may be said to 
have finally set it aside, by showing how such 
breaks in the succession of organic remains 
may be completely explained by regarding 
them as marking enormous chronological 
gaps in the records of what was neverthe- 
less a continuous organic evolution. How 
soon these fertile ideas in the Origin of 
Species bore fruit was shown a few years 
after the publication of that work, when 
Kamsay gave his two brilliant addresses to 
the Geological Society on breaks in the 
succession of strata in Britain 59 . 

When the history of the progress of 
science in the nineteenth century comes to be 
written the views expressed in the geological 
chapters of Darwin's great work, whether novel 
or enforcing with new emphasis what had been 
more or less clearly perceived before, will 
be seen to mark a notable epoch in modern 
geology. They have thoroughly permeated 
the recent literature of the science, insomuch 
that there is sometimes a risk that the student 



64 CHARLES DARWIN AS GEOLOGIST 

who finds them so intimately incorporated 
may lose sight of the source to which he 
owes them. As one of the survivors of the 
time when the Origin of Species appeared I 
am glad to be privileged with this public 
opportunity of acknowledging the deep debt 
which the science of geology, in many of its 
departments and in the whole spirit by which 
it is now informed, owes to the life-long 
labour of the author of that work. Geologists 
are proud to claim him as one of themselves 
and as one of the great masters by whom 
their favourite science has been advanced. 
In their name, therefore, I beg to offer at 
this centennial celebration our tribute of 
gratitude and admiration to the memory 
of Charles Darwin. 



NOTES 

1 The best account of the Neptunist doctrines is to be 
found in Robert Jameson's Treatise on Geognosy (1808), 
which forms the third volume of his System of Mineralogy. 
Owing in large measure to the eloquence and personal 
influence of Abraham Gottlob Werner, the great apostle of 
this creed at the mining school of Freiberg in Saxony, these 
doctrines (often known as Wernerian or Wernerism) enjoyed 
a great vogue all over Europe in the later decades of the 
eighteenth and the earlier of the nineteenth century. But 
their prevalence rapidly diminished after his death in 1817, 
especially when some of his more distinguished pupils, such 
as L. von Buch and A. von Humboldt, abandoned them. 
Jameson, however, who had studied under Werner, 
remained longer unconvinced of the untenability of his 
master's opinions. In 1804 he had become Professor of 
Natural History at the University of Edinburgh. Four 
years later (as if in rivalry to the Geological Society of 
London, which was started in the previous year) he founded 
the Wernerian Society, one main object of which was to 
support and propagate the teaching of Freiberg. Even so 
late as 1826, when Darwin attended his lectures, he was 
still inculcating to his students the then discredited notions 
of Werner as to the aqueous origin of igneous rocks. He 



66 CHARLES DARWIN 

afterwards at a meeting of the Royal Society of Edinburgh 
frankly acknowledged that he had been compelled to abandon 
the distinctive tenets of Wernerism. It has not been 
possible to recover the precise date of this recantation, 
though both the late Sir Robert Christison and Professor 
J. H. Balfour assured me that they had been present when 
it was made. It must have taken place between the years 
1826 and 1838, for in the latter year Hay Cunningham 
published his Plutonist description of Salisbury Craigs, 
which he said was " nearly that which the Professor now 
delivers to his pupils" (Essay on the Geology of the 
Lothians, 1838, p. 56, footnote). 

2 It was in this country that the Vulcanist or Plutonist 
creed was first clearly proclaimed by Button in his Theory of 
the Earth, of which the first sketch was laid before the Royal 
Society of Edinburgh in 1785, and the enlarged form in 
two octavo volumes ten years later. The general principles 
expressed in this work were after Button's death expounded 
and enforced with admirable force and elegance by John 
Playfair in his flliistrations of the Huttonian Theory (1802). 
These two authors may be said to have laid the foundations 
of the physical side of modern geology. While fully 
Plutonist in their teaching they yet recognised, more vividly 
than had ever been done before, the potent influence of the 
aqueous and atmospheric influences which have ceaselessly 
modified the surface of the globe. 

In this country the controversy between the two schools 
of the Neptunists or "Wernerians and the Plutonists 
(Vulcanists) or Huttonians was prosecuted with much 
vigour, while it lasted, but it had practically died out some 
time before the middle of last century. One of the most 
curious signs of its decay is to be found in the last volumes 



AS GEOLOGIST 67 

of the Memoirs of the Wernerian Society, which are as frankly 
Plutonist as the previous volumes had been exclusively 
Neptunist. One cause of the cessation of the warfare is 
undoubtedly to be recognised in the ultimate influence of 
the Geological Society, which was founded in 1807 for the 
purpose of investigating the facts of geology rather than the 
advocacy of any theory regarding them. The continual 
advance of the doctrines taught by Hutton and Playfair is 
well indicated by the successive appearance of memoirs in 
scientific journals and also independent treatises which 
stand out as landmarks in the progress of geology, culmi- 
nating in 1830 when the first volume of Lyell's Principles 
of Geology made its appearance. It is interesting to 
remember that in his relations to geological science Charles 
Darwin lived through this transition period. He had 
actually been a pupil of Jameson, the high priest of 
Wernerism in Britain, and he became one of the earliest 
and most effective followers of Lyell, the great prophet of 
Uniformitarianism. 

3 It was natural that the phenomena of geology, appeal- 
ing powerfully to the imagination in their striking memorials 
of terrestrial revolutions, should favour the rise of the 
Catastrophist school. They seemed to require the operation 
of stupendous convulsions, and to be wholly inexplicable by 
the action of any forces now visible to human observation. 
It was only by degrees, and after Lyell's able advocacy, that 
the efficacy of apparently feeble causes, acting through long 
periods of time, came to be recognised. Among the 
champions of this school none was more eloquent and out- 
spoken than Adam Sedgwick, the illustrious Woodwardian 
Professor at Cambridge. In the address which he gave to 
the Geological Society on quitting the presidential chair on 

52 



68 CHARLES DARWIN 

February 18, 1831, he vigorously criticised the uniformi- 
tarian doctrines which had been in the previous year 
advocated with so much persuasive power by Lyell in the 
first volume of his Principles. The following passages 
may be quoted from this address. 

" Though we have not found the certain traces of any 
great diluvian catastrophe which we can affirm to be within 
the human period ; we have, at least, shown that paroxysms 
of internal energy, accompanied by the elevation of moun- 
tain-chains, and followed by mighty waves desolating whole 
regions of the earth, were a part of the mechanism of nature." 
11 Volcanic action is necessarily paroxysmal ; yet Mr Lyell 
will admit no greater paroxysms than we ourselves have 
witnessed no periods of feverish spasmodic energy, during 
which the very framework of nature has been convulsed and 
torn asunder. The utmost movements that he allows are a 
slight quivering of her muscular integuments." Proc. Geol. 
Soc., Vol. I, pp. 307, 314. 

4 The uniformitarian doctrines in geology were clearly 
enunciated in Button's Theory of the Earth (see especially 
Vol. II, pp. 205, 328, 467, 510, 547), and were admirably 
expounded in Playfair's Hlmtrations of the Huttonian 
Theory, wherein a large body of evidence was brought 
forward in support of them. Twenty years later Karl E. A. 
von Hoff began to publish his laborious chronicle of all the 
geological changes recorded by man within the times of 
human history (Geschichte der durch tlberlieferung nachge- 
wiesenen naturlichen Verdnderungen der Erdoberflache, 
Vol. I, 1822 ; n, 1824 ; in, 1834 ; iv, 1840 ; v, 1841). 
There could not have been gathered together a more impos- 
ing array of proof of the nature and importance of the 
vicissitudes of the earth's surface now in progress than is 



A8 GEOLOGIST 69 

contained within these meritorious volumes. But the 
cumulative effect of such changes, prolonged through vast 
periods of time, was not for some time realised by the general 
body of geologists. It was reserved for Lyell to point out 
the deductions that might logically be drawn from the large 
accumulation of evidence by his time available, and thus 
to place geology on a more solid foundation with a rightful 
claim to a higher rank than it had hitherto held among the 
observational sciences. Darwin, who had known something 
of its state in earlier days, never wavered in his conviction 
that Lyell had revolutionised the science of geology. 

5 The Life and Letters of Charles Darwin, including an 
Autobiographical Chapter, edited by his son, Francis 
Darwin. Three vols. London, 1887. Vol. i, pp. 41, 42. 
See also my Founders of Geology, 2nd edn., p. 329, for an 
account of another excursion to Salisbury Craigs, where the 
Plutonist notions were contemptuously rejected by one of 
the Wernerian faith. 

6 Life and Letters, Vol. I, p. 55. 

7 Ibid., pp. 56, 189. 

8 Ibid., p. 189. 

9 The title of this work is Principles of Geology, being 
an Attempt to explain the Former Changes of the Earth's 
Surface, by reference to Causes now in Operation. The first 
volume which, as stated in the text, appeared in January, 
1830, was followed by the second in January, 1832, while 
the third and concluding volume was issued in May, 1833. 

10 Life and Letters, I, p. 72. 

11 Ibid., I, p. 73. 

12 Ibid., I, p. 62. 

13 Ibid., I, p. 66. 

14 Ibid., I, p. 233. 



70 CHARLES DARWIN 

15 More Letters of Charles Darwin, a Record of his 
Work in a series of hitherto unpublished Letters, edited by 
Francis Darwin (1903), Vol. I, p. 9. 

16 Life and Letters, I, p. 249. 

17 Journal of Researches into the Natural History and 
Geology of the Countries visited during the wyage of 
H.M.S. "Beagle" round the World, Chap, xiii., p. 280. The 
first edition of this work was published in 1839 as Vol. m 
of The Narrative of the Surveying Voyages of Her Majesty's 
Ships "Adventure" and "Beagle" between the years 1826 and 
1836. The citations in these Notes are made from the 
second edition, published 1845 in Murray's Colonial and 
Home Library. 

The Museum of the Zoological Society was dispersed 
many years ago, but the important parts of its contents 
were placed in the Natural History galleries of the British 
Museum. In answer to an application which I made to 
Mr S. F. Harmer, F.R.S., Keeper of Zoology in the Natural 
History Museum, Cromwell Road, for information as to 
Darwin's specimen, he has been so good as to send me the 
following particulars : " The fox to which you refer as 
having been killed by Charles Darwin with a geological 
hammer is in our collection. It is represented by a skin 
and a skull, and it is the type of Canis fulvipes, "Water- 
house." 

18 More Letters, Vol. I, p. 14. 

19 Life and Letters, Vol. I, p. 263. 

20 Geological Observations on South America, being the 
Third Part of the Geology of the Voyage of the "Beagle" 
during the years 1832 to 1836. 1846. Pp. 175, 202, 232, 
241, 247. 

21 Geological Observations on the Volcanic Islands, 



AS GEOLOGIST 71 

visited during the Voyage of H.M.S. " Beagle? together 
with some brief notes on the Geology of Australia and the 
Cape of Good Hope, being the Second Part of the Geology of 
the Voyage of the "Beagle" 1844. Chap. iii. 

22 One of the most striking conclusions contained in 
Darwin's volume on " Volcanic Islands " is to be found in 
his account of the great granitic masses of South America. 
He not only perceived that there might be a " sinking of 
crystals through a viscid substance like molten rock " 
(p. 118) by virtue of their specific gravity being greater 
than that of the base, but he inferred that in large plutonic 
masses " a certain amount of separation of their constituent 
parts has often taken place." He goes on to remark, "I 
suspect this from having observed how frequently dykes of 
greenstone and basalt intersect widely extended formations 
of granite and the allied metamorphic rocks " (p. 123). He 
had never examined a district in an extensive granitic region 
without discovering such dykes. He thinks it probable 
" that these dykes have been formed by fissures penetrating 
into partially-cooled rocks of the granitic and metamorphic 
series, and by their more fluid parts, consisting chiefly of 
hornblende [or augite] oozing out, and being sucked into 
such fissures/' "We may admit, in the case of a great 
body of plutonic rock being impelled by repeated movements 
into the axis of a mountain-chain, that its more liquid 
constituent parts might drain into deep and unseen abysses ; 
afterwards, perhaps, to be brought to the surface under the 
form, either of injected masses of greenstone and augitic 
porphyry, or of basaltic eruptions. Much of the difficulty 
which geologists have experienced when they have compared 
the composition of volcanic with plutonic formations, will, 
I think, be removed, if we may believe that most plutonic 



72 CHARLES DARWIN 

masses have been, to a certain extent, drained of those 
comparatively weighty and easily liquefied elements, which 
compose the trappean and basaltic series of rocks " (p. 124). 
For two examples of the segregation of a basic periphery in 
granitic bosses see Messrs Dakyns and Teall, Quart. Journ. 
Geol Soc., XLVIH (1892), p. 104 ; and Mr A. Harker, op. 
cit., L (1894), p. 311 ; LI (1895), p. 125. 

23 Darwin made a special study of this subject wherever 
he had an opportunity of examining slates and schists in 
South America, and his observations and conclusions have 
been confirmed by later observers. " I cannot doubt," he 
says, " that in most cases foliation and cleavage are parts 
of the same process : in cleavage there being only an in- 
cipient separation of the constituent minerals : in foliation, 
a much more complete separation and crystallisation" 
(Geol. Obs. on South America, p. 166). This is doubtless 
true in regard to such rocks as clay-slate, phyllite, &c., 
where the successive stages from uncleaved, through 
cleaved into foliated rocks and perfect schists can be 
traced. Darwin also conceived that "the planes of 
cleavage and foliation are intimately connected with the 
planes of different tension to which the area was long 
subjected before the cessation of the molecular movement " 
(p. 168). He saw that the direction of these planes was 
always parallel to the principal axes of elevation (p. 169). 

24 Geological Observations on South America, Chap. i. 

25 Op. cit., p. 32. 

26 Journal of Researches, Chap. xv. p. 321. 

27 Op. cit., Chap. xiv. p. 310. 

28 Ibid. 

29 Geological Observations on South America, p. 135. 
He believed that "the excessively disturbed condition of 



AS GEOLOGIST 73 

the strata in the Cordillera, so far from indicating single 
periods of extreme violence, presents insuperable difficulties, 
except on the admission that the masses of once liquefied 
rocks of the axes were repeatedly injected, with intervals 
sufficiently long for their successive cooling and consolida- 
tion " (p. 248). 

30 The passages in which Professor Suess controverts 
Darwin's views will be found in the first and second 
volumes of his Antlitz der Erde (Vol. I, pp. 95 105 and 
Vol. n, pp. 522 534 of the English translation of his 
work which has recently appeared under the title of The 
Face of the Earth, edited by Prof. Sollas). One particular 
observation has been especially singled out for criticism. 
Darwin has recorded that on the island of San Lorenzo, 
at a height of 85 feet above the sea, he found a bed 
two feet thick of recent marine shells, some of them with 
their insides incrusted with barnacles and serpulae. From 
this bed, amongst light corallines, horny ovule-cases of 
mollusca and roots of sea-weeds, he extracted some bones 
of birds, heads of Indian corn, a piece of woven rushes, 
and another piece of nearly decayed cotton string. He 
regarded these relics of human workmanship to have been 
contemporaneously embedded with the shells, and inferred 
that the land had here been upraised 85 feet since Indian 
man inhabited Peru (Geol. Obs. on South America, p. 49, 
and Journal of Researches, Chap. xvi. p. 370). 

The same locality was visited a few years later by 
Prof. J. D. Dana, who published the following comment upon 
Darwin's deductions. "The argument [for an elevation 
of this coast] is urged with force and discrimination by 
Mr Darwin. My own observations have been confined 
to so small a part of the coast, that any opinion here 



74 CHARLES DARWIN 

expressed is entitled to but little weight, especially as I 
am unable to draw comparisons with the beds in other 
portions of the western coast alleged as similar in character. 
I may, however, frankly confess that the evidence does not 
seem to me to place the question beyond doubt." He then 
proceeds to state his "sources of doubt." These are (1) 
the occurrence of the shells in an irregular unstratified 
bed, just beneath or in the soil ; (2) the absence of an 
inner cliff at the place. He thinks it more likely that the 
shells together with the relics of human occupation were 
accumulated by the Peruvians themselves, and he goes 
on to refer to the habits of the Patagonians and New 
Zealanders in transporting shell-fish from the sea-coast 
inland. He suggests that possibly a rush of waters over 
the land, such as is occasionally produced by an earth- 
quake, might have been concerned in the spreading out 
of these remains, though without further examination, he 
does not feel ready to attribute the effects to this cause 
(Report of United States Exploring Expedition (1838 
1842) under C. Wilkes, Vol. X. Geology (1849), p. 591). 

Professor Suess assumes that what Darwin observed 
was merely one of the "kitchen middens" which occur 
at many localities along the margin of the coast. He 
remarks: "When Darwin visited these coasts in 1835 
little was known as to the wide distribution of such 
remains. It must therefore have filled him with the 
greatest astonishment to meet with a thread, pieces of 
wicker-work and other traces of human activity in a 
deposit of sea-shells on the island of San Lorenzo, near 
Callao, at a height of 85 feet above the sea, and he may 
well, according to the state of knowledge at that time, 
have regarded it as a proof of recent elevation. Dana, 



AS GEOLOGIST 75 

who visited the place some years later, has already ex- 
plained the circumstance." He cites in a footnote the 
passage from Dana's work above quoted. I leave any 
impartial reader to judge whether the extremely guarded 
statement of the American geologist " explains the circum- 
stance" or justifies the summary rejection of Darwin's 
observation. 

When Darwin read the passages in Dana's volume, 
which was published in 1849, he was naturally somewhat 
indignant. Thus in writing to Lyell in December of that 
year about the volume, he referred to Dana as " disputing 
my conclusions without condescending to allude to my 
reasons. Thus, regarding S. Lorenzo elevation, he is 
pleased to speak of my ' characteristic accuracy,' and then 
gives difficulties (as if his own) when they are stated by 
me, and I believe explained by me" (More Letters of 
Charles Darwin, Vol. n, p. 226). 

In the passage above quoted Prof. Suess expresses 
his opinion that at the time of Darwin's exploration in 
South America little was known of the wide distribution 
of sea-shells in the interior of the country by the in- 
habitants. But he has omitted to notice the references 
to this mode of transport which are made by Darwin 
himself, who positively says that he was " well aware from 
what he had seen at Chiloe and in Tierra del Fuego, that 
vast quantities of shells are carried during successive ages, 
far inland, where the inhabitants chiefly subsist on these 
productions" (Geol. Obs. on South America, p. 33). 

One of the grounds on which Darwin convinced himself 
that he was dealing not with kitchen-middens but with 
natural deposits of marine origin, was derived from an 
examination of the comminuted organic debris found filling 



76 CHARLES DARWIN 

the shells and diffused through the enclosing earth. This 
material " was in considerable part composed of minute 
fragments of the spines, mouth-bones and shells of echini, 
and of minute fragments of chiefly very young Patellae, 
Mytili and other species " (Ibid}. Not until he returned 
home and had an opportunity of unpacking and studying 
his collections, did he realise how fully this accumulation 
of comminuted organisms confirmed his conclusion as to 
"the marine origin of the earth in which many of the 
shells are packed. Considering these facts," he adds, "I 
do not feel a shadow of doubt that the shells, at the height 
of 1300 feet, have been upraised by natural causes into 
their present position " (Ibid, footnote). 

The endeavour to account for all the shelly deposits of 
the coast of Chili as mere human refuse has been extended 
to the eastern side of the continent by various writers. 
The most recent author who has treated of this subject, 
Dr H. von Ihering, Director of the Museum of Sao 
Paulo, Brazil, in a detailed memoir entitled Les Mollusques 
Fossiles du Tertiaire et du Cretace Sup&rieur de I Argen- 
tine^ which forms the whole of Vol. vn of the third series 
of the Anales del Museo National, Buenos Aires (1907), 
refers to the abundant evidence of a former sea-margin, 
30 to 40 metres above the present level of the sea, along 
the coast of Brazil and Argentina. He alludes to vast 
accumulations of shells in southern Brazil, called by the 
natives sambaquis, which sometimes form hills that rise 
10 or 15 metres above the low marshy land, while in other 
places the equivalent deposits consist only of more or less 
clayey soil through which oysters and other shells are 
scattered. These sambaquis are sometimes formed entirely 
of valves of Anamalocardia, in other places exclusively of 



AS GEOLOGIST 77 

oysters or of valves of Corbula mactroides prisca. Layers 
of one or other of the shells may be seen to alternate in 
some of the mounds. "Some authors," says the writer, 
"compare these deposits to the kitchen-middens of Denmark, 
but the conditions are quite distinct, since the shells are 
never found mingled with bones of animals of the chase, 
of fish, of wood charcoal, of fragments of pottery or other 
human relics. The archaeological objects which are met 
with in these deposits are only associated with the skeletons 
which have there been buried " (p. 430). Dr von Ihering adds 
that he need not enter into the details of this matter, as he 
has already fully discussed it in several communications, 
of which he subjoins a list. Dr Florentino Ameghino, so 
well known for his numerous contributions to the geology 
and vertebrate palaeontology of Argentina, has pointed out 
the distinction between true kitchen-middens and natural 
deposits of shells on the Patagonian coast (p. 432). 

31 Geological Observations on South America, p. 33. 

32 The title of this Memoir is "On the Connexion of 
certain Volcanic phenomena and on the Formation of 
Mountain-chains and the effects of Continental elevations" 
(Trans. Geol Soc., 2nd Ser., v, 1840, pp. 601632). In this 
paper the author expresses the opinion that the earthquakes 
of South America are " caused by the interjection of liquefied 
rock between strata " (p. 615). He supposes that " the train 
of connected volcanoes in Chili and the tract of coast upraised, 
extending together for a length of more than 800 geographical 
miles rest on a sheet of fluid matter " (p. 630). He believes 
that "mountain-chains are only subsidiary and attendant 
phenomena on continental elevations " (p. 623). He argues 
that while " mountain-chains are the effects of continental 
elevations, continental elevations and the eruptive force of 



78 CHARLES DARWIN 

volcanoes are due to one great motive power now in pro- 
gressive action ; therefore the formation of mountain-chains 
is likewise in progress and at a rate which may be judged 
of by either phenomenon, but most nearly by the growth of 
volcanoes " (p. 629). He thinks this subterranean " power, 
now in action, and which has been in action with the same 
average intensity (volcanic eruptions being the index) since 
the remotest periods, not only sufficient to produce, but 
which almost inevitably must have produced, unequal 
elevation on the lines of fracture " (pp. 624, 625). 

33 Journal of Researches, pp. 275, 291, 310. 

34 Trans. Geol Soc., 2nd Ser., v (1840), p. 631. 

35 Darwin first published his theory of coral reefs in a 
brief statement read to the Geological Society in 1837 
(Vol. H of the Society's Proceedings, 1838, pp. 552554), 
with the title " On certain Areas of Elevation and Subsidence 
in the Pacific and Indian oceans, as deduced from the study 
of Coral-formations." The first edition of his book on the 
subject appeared in 1842 as the First Part of the Geology 
of the Beagle, with the title, The Structure and Distribution 
of Coral Reefs. 

The first note of objection to the general applicability of 
Darwin's explanation appears to have been raised by 
Professor Louis Agassiz in 1851 (Bull. Mm. Comp. Zool., 
Vol. i), who from his investigation of the Florida reefs came 
to the conclusion that they furnished no evidence of 
subsidence an inference which was subsequently sup- 
ported by the more detailed investigations of his son, 
Prof. Alexander Agassiz, in a paper on the Tortugas and 
Florida Reefs (Trans. Amer. Acad., xi, 1883). More 
important evidence in the same direction was published 
by Prof. Carl Semper from the Pelew Islands in 1863 



AS GEOLOGIST 79 

(ZeitscL Wissensch. Zoologie, xin, 1863, p. 558 ; Verhandl. 
Physik-med. Geselkch. Wwrzburg, 1868, and Die Philippinen 
und ihre Bewohner, 1869), and by Dr J. J. Rein from 
Bermuda (Bericht. SencTcenberg. Naturforsch. Gesellsch., 
1869 70, p. 157). These writers insisted on evidence of 
uplift where, according to Darwin's view, there ought to 
have been depression. 

In 1874 Darwin published a second edition of his volume 
on Coral-reefs, revised and in some parts almost re-written. 
It contained some additional matter, and took notice of 
Semper's criticism, but without attaching to it any great 
importance as necessitating a modification of the theory 
originally promulgated. He was well aware that in many 
places coral-reefs have been upheaved, and he cites examples 
of them. He contemplated the association of elevation 
with volcanic action, and the absence of active volcanoes 
over vast regions where coral-islands are numerous seemed 
to him a corroboration of his view that these areas are 
sinking. 

But he was at this time in the full tide of the biological 
researches which engrossed his attention during the years 
that followed the publication of the Origin of Species, and 
it was hardly possible for him to keep in touch with the 
progress of geological enquiry. In the preface to the second 
edition of his Coral Islands he says that he might have 
greatly improved his map of the distribution of coral-reefs 
if he " had been better situated during the last thirty years, 
for hearing of recent discoveries in the Pacific, and for con- 
sulting charts published in other countries." He was 
probably unaware of the early objections of Louis Agassiz 
and of those made in later years by Dr Rein. It is doubt- 
ful also whether or not he became aware of the large body 



80 CHARLES DARWIN 

of evidence which, after the publication of his second 
edition, came from many widely separated localities with 
constantly increasing force in opposition to his theory. 
But even if this fresh information reached him, he was 
content to let the matter rest where he had left it. A third 
edition of his book was issued after his death under the 
care of Professor Bonney in 1889. 

In 1880, after the great voyage of the Challenger had 
been carried out, Sir John Murray published a theoretical 
explanation of the origin of coral-islands without the aid of 
subsidence. Pointing out, as Darwin had already done (see 
Note 51), that the oceanic islands are almost all of volcanic 
origin and thus that no evidence from continental rocks can 
be adduced in favour of the former existence of land now 
submerged, he argued that the submarine ridges and peaks 
which rise to various distances from the surface are pro- 
bably due to the protrusion of volcanic materials. These 
platforms, he conceived, might be brought in two ways 
to the proper level at which reef-building polypifers could 
live and grow. Those which rose above the sea-level could 
be worn away by breakers and currents until they were 
reduced to the lower limit of wave-action, while those 
which lay at greater depths could be brought up to the 
requisite level by the deposit upon them of the remains 
of the calcareous pelagic organisms which swarm in the 
upper waters of tropical seas. Thus, partly by erosion and 
partly by the accumulation of organic debris, fitting building- 
places could be furnished for the growth of corals. The 
chief reef-builders flourish most vigorously on the outer 
margin, amidst the play of the waves which are always 
bringing them food. By the force of the breakers huge 
blocks of the coral-rock are torn off the face of the reef. 



A8 GEOLOGIST 81 

These form a steep talus below, and on the top of this talus 
the reef continues to grow outward (J. Murray, Proc. Roy. 
Soc. Edin., x, 187980, p. 505 ; xvn, 1889, p. 79. In the 
Proceedings of the Royal Physical Society of Edinburgh, 
Vol. vni, p. 1, 1 gave an account of the state of the question 
up to the year 1884). 

Strong support to these views has been given by 
Professor Alexander Agassiz, who in his numerous and 
extensive cruises has acquired a more extended and inti- 
mate knowledge of coral-reefs than any living naturalist. 
His various published Reports afford an ample picture of 
the structure and growth of these reefs all over the Pacific 
Ocean as well as in the warmer waters of the western 
Atlantic. The reader will find an index to the more 
important contributions to the literature of coral-reefs on 
p. 614 of the first volume of my Text-book of Geology. The 
latest work of note is the voluminous Report on the borings 
carried out on the Atoll of Funafuti, published by the 
Royal Society (The Atoll of Funafuti Borings into a 
Coral Reef and the Results ; Being the Report of the Coral 
Reef Committee of the Royal Society y 1904. See also 
A. Agassiz, Mem. Mus. Comp. ZooL, Harvard, Vol. xxvin 
(1903), p. 212). The cores extracted from a bore sunk 
on the reef of this atoll down to a depth of 1114 feet were 
carefully studied by the most competent naturalists and 
yielded reef-building genera from top to bottom. The base of 
the calcareous mass was not reached, but its total thickness 
was proved to be more than 1100 feet. If it could be 
certainly shown that this mass consists of coral-rock in 
its original position of growth this particular atoll would 
demonstrate subsidence of the sea-floor, and could thus be 
cited in support of Darwin's view. But if the mass is made 

G. 6 



82 CHARLES DARWIN 

up of material broken by the waves from the face of the 
reef during its slow seaward extension, or if it consists in 
part of Tertiary limestone, it would not give any certain 
proof of change of level. 

If however we turn to the abundant and striking evi- 
dence of uprise among the coral islands of the Pacific and 
Indian Oceans and the reefs in the western part of the 
Atlantic, which has been brought to light in recent years 
by A. Agassiz, H. B. Guppy and others, it is, I think, 
impossible any longer to insist on the vast area of subsi- 
dence in these oceans which Darwin's theory required. He 
undoubtedly pointed out a vera causa in subsidence, which 
under the requisite conditions would give rise to the suc- 
cession of different types of reef ending in true atolls. But 
it must be admitted that the later explanation, while quite 
compatible with the existence of local subsidence in different 
areas, is in harmony with overwhelming evidence in favour 
of elevation rather than depression among many oceanic 
islands. 

36 Zoology of the Voyage of H.M.S. Beagle, Vol. I, 
Fossil Mammalia described by Richard Owen, with a Geo- 
logical Introduction by Charles Darwin, 1838. The hope 
here expressed by the great comparative anatomist has 
been abundantly fulfilled by the successful labours of later 
investigators, especially those of the Argentine Republic 
and of the expedition to Patagonia sent out from Princeton 
University. 

37 Geological Observations on South America, p. 247. 
See also pp. 136, 185187. 

38 Volcanic Islands, p. 91. 

39 Ibid., p. 136. 

40 Journal of Researches, Chap, xv., pp. 316, 317. 



AS GEOLOGIST 83 

41 Life and Letters, Vol. i, p. 265. 

42 Ibid., Vol. i, p. 267. 

43 Life and Letters of the Reverend Adam Sedgwick, by 
John Willis Clark and Thomas McKenny Hughes, 1890, 
Vol. i, p. 484. 

44 "Observations on the Parallel Roads of Glen Roy 
and of other parts of Lochaber in Scotland, with an attempt 
to prove that they are of marine origin" (Phil. Trans., 
1839, pp. 39 82). In this paper Darwin had in his mind 
that the only conceivable barriers of the supposed lake or 
lakes must have consisted of rock or of detritus, and he 
rightly refused to believe the supposition that barriers of 
these materials could be admitted. The idea of barriers of 
ice had not then been suggested, and the only waters that 
seemed capable of accounting for the terraces were those of 
the sea. In the following year, however, Agassiz showed 
that Scotland must have been deeply buried in ice, and 
suggested that the Parallel Roads marked the levels of 
lakes that had been ponded back by glaciers (Proc. Geol. 
Soc., in, p. 327 ; Edin. New Phil Jowrn., xxxra, p. 217 ; 
Atlantic Monthly for June, 1864). "When Mr Jameson's 
paper was published in which this view was completely 
demonstrated (Quart. Journ. Geol. Soc., Vol. xix, p. 235), 
Darwin frankly admitted his own explanation to have been 
erroneous (More Letters, Vol. n, pp. 188193). 

45 Life and Letters, i, p. 58. The same simile was 
used in the Origin of Species, p. 330. The references in 
these Notes are to the sixth edition of the work. 

46 This paper bears the title "Notes on the effects 
produced by the Ancient Glaciers of Caernarvonshire, and 
on the Boulders transported by Floating Ice " (Phil. Mag., 
Vol. xxi, 1842, p. 180). It is an interesting example of A 



84 CHARLES DARWIN 

characteristic phase in the evolution of opinion regarding 
the phenomena of the Ice-Age. At first the so-called 
" Drift," also scattered boulders and striated rock-surfaces, 
were all attributed to powerful debacles produced by earth- 
quake shocks whereby the sea was violently launched across 
the surface of the land. When the idea gained ground that 
ice had in some way helped in these operations, the super- 
ficial accumulations were still regarded as having been 
deposited in the sea, over which icebergs and floes trans- 
ported materials from the land. Even when the presence 
of former glaciers among the mountains of Britain was 
admitted, the general distribution of ice-borne boulders over 
the face of the country was still attributed to the sea. In 
this paper of Darwin's (which followed a previous communi- 
cation by Buckland " On the Diluvio-glacial Phenomena in 
Snowdonia and the adjacent parts of North Wales"), while 
the moraines with their boulders and the ice-worn domes 
of rock are recognised as manifestly due to valley-glaciers, 
the boulders lying scattered over the surrounding district 
and the till underneath them are spoken of as having been 
transported by floating ice when the mountains formed islets 
in the sea. In like manner, in his paper on the Parallel 
Roads he took for granted that the boulders in the Lochaber 
district had been distributed by floating ice. It was long 
before the efficacy of land-ice as an agent in the transport 
of erratics was adequately acknowledged. 

47 This was an article " On the power of Icebergs to 
make rectilinear, uniformly-directed Grooves across a sub- 
marine undulatory surface" (Phil. Mag., x, 1855, p. 96). 
A growing disposition was then showing itself to doubt 
whether floating ice could mould itself upon an irregular 
rock-surface. The way in which on glaciated rocks the 



AS GEOLOGIST 85 

striae mount over the protuberances and descend into the 
hollows of such surfaces was gradually coming to be recog- 
nised as the work of land-ice. Darwin still clung to the 
older faith. He thought that icebergs can mould them- 
selves more perfectly than glaciers on the rocks over which 
they are driven, and "can slide straight onwards over 
considerable inequalities, scratching and grooving the un- 
dulatory surface in long straight lines." 

48 " On the formation of Mould," Proc. Geol Soc., n 
(1838), pp. 574576 ; Trans. Geol. 8oc., 2nd Ser., v (1840), 
pp. 505510. 

49 Button was the first geologist who grasped the 
general principle that although a layer of soil remains as a 
covering on the land, its component particles are con- 
tinually being washed off the surface while, in compensation, 
fresh materials are added to it from the slow disintegration 
of the rocks underneath (Theory of the Earth, Vol. I, 
pp. 205, 210 ; H, pp. 93, 94, 95, 96, 184, 196, 202, 242, 
244). The question was stated with characteristic clear- 
ness and precision by Playfair. "It is interesting to 
observe," he remarks, " how skilfully nature has balanced 
the action of all the minute causes of waste, and rendered 
them conducive to the general good. Of this we have a 
most remarkable instance in the provision made for pre- 
serving the soil, or the coat of vegetable mould, spread out 
over the surface of the earth." He points out that although 
its materials are easily and continually washed away by the 
rains and carried down by the rivers into the sea, it still 
remains as a covering on the land, being augmented from 
other causes. " This augmentation evidently can proceed 
from nothing but the constant and slow disintegration of 
the rocks. In the permanence, therefore, of a coat of 

6-3 



86 CHARLES DARWIN 

vegetable mould on the surface of the earth, we have a 
demonstrative proof of the continual destruction of the 
rocks ; and cannot but admire the skill with which the 
powers of the many chemical and mechanical agents, em- 
ployed in this complicated work, are so adjusted as to make 
the supply and the waste of the soil exactly equal to one 
another " (Illustrations of the Huttonian Theory, 103). 

These conclusions, so vital for an intelligent compre- 
hension of how a land-surface, even when covered with 
vegetation, does not wholly escape from degradation, were 
for many years ignored by later writers. It is true that 
Lyell, in commenting upon the passage above quoted from 
Playfair's treatise, supports its main contention, though he 
adds that it did not take into account the organic material 
supplied from the atmosphere (Principles of Geology, 
first edit., Vol. n, p. 188). How little importance was 
generally attached to the Huttonian view of this matter 
may be gauged from the language used by Sedgwick from 
the chair of the Geological Society, when he vehemently 
opposed the uniformitarianism maintained in the then 
recently published first volume of LyelPs Principles. "The 
destructive powers of nature," he said, "act only upon 
lines, while some of the grand principles of conservation 
act upon the whole surface of the land. By the processes 
of vegetable life, an incalculable mass of solid matter is 
absorbed, year after year, from the elastic and non-elastic 
fluids circulating round the earth, and is then thrown 
down upon its surface. In this single operation there is a 
vast counterpoise to all the agents of destruction " (Proc. 
Geol Soc., i, 1831, p. 303. This portion of Sedgwick's 
address was made the subject of some caustic remarks by 
Lyell in the second volume of his Principles, p. 197). 



AS GEOLOGIST 87 

But the most absolute negation of the Huttonian 
doctrine is to be found in the lectures given at the 
College de France by filie de Beaumont, the most dis- 
tinguished French geologist of his day. He devoted a 
special discourse to the subject, wherein he entered upon 
a detailed endeavour to prove that neither the soil, nor the 
general surface of the land, nor the beds of rivers, have 
undergone any perceptible modification during the time of 
human history. He came to the conclusion that while 
there are many places on the surface of the globe where 
degradation is continual and plainly visible, this waste is 
appreciable precisely because elsewhere the vegetable soil 
preserves its integrity almost intact during immense periods 
of time. "The surface of the ground, covered with vegeta- 
tion, remains without sensible alteration for thousands of 
years. It is a fixed point, a zero from which the phenomena 
can be measured, which advance with rapidity " (Lemons de 
Geologie Pratique, tome I, 1845, p. 182). Many years ago 
I pointed out the fallacy in this reasoning (Trans. Geol. 
Soc. Glasgow, Vol. m, 1868, p. 170). 

]j!lie de Beaumont made no reference to Hutton or 
Playfair, nor to Darwin's paper, which had been published 
three years before he lectured on the subject. That the 
views of the English naturalist met with little favour among 
geologists was shown when, in reviewing the progress of 
geology, D'Archiac summarised with approval the observa- 
tions and conclusions of ]5lie de Beaumont, but referred to 
Darwin's views as a "singulidre thebrie." "We fear," he 
added, "that the learned English traveller has been too 
much prepossessed by the importance of an organic influence, 
which could have no effect save in low and damp meadows. 
Cultivated lands, woods, high-lying meadows, afford no 



88 CHARLES DARWIN 

support to this view. The formation of the vegetable soil 
results from the simultaneous co-operation of mechanical 
and chemical agents, often helped by human industry " 
(Histoire des Progrts de la Geblogie, tome I, 1847, p. 224). 
Darwin in his volume on Vegetable Mould took notice of 
both these French writers. He remarks that D'Archiac 
" must have argued from inner consciousness and not from 
observation, for worms abound to an extraordinary degree 
in kitchen gardens, where the soil is continually worked " 
(p. 4). 

50 The Formation of Vegetable Mould through the Action 
of Worms, with Observations on their Habits, 1881. The 
popularity of this volume was immediate. We learn from 
Life and Letters, Vol. in, p. 218, "that in the three years 
following its publication, 8500 copies were sold," a sale 
relatively greater than that of the Origin of Species. 

51 Origin of Species, Chap, xii., pp. 324, 347. He 
adduces his reasons for this belief, one of the most important 
being the geological argument that the almost universally 
volcanic composition of oceanic islands does not favour the 
admission " that they are the wrecks of sunken continents. 
If they had originally existed as continental mountain- 
ranges, some at least of the islands would have been formed, 
like other mountain summits, of granite, inetainorphic 
schists, old .fossiliferous and other rocks, instead of con- 
sisting of mere piles of volcanic matter." His opinion was 
in favour of the view that the present continents and 
oceans have long remained in nearly the same relative 
positions (Chap, x., p. 288). 

52 Principles of Geology, ninth edit., 1853, p. 146. 
On the same page he affirms " No satisfactory proof has 
yet been discovered of the gradual passage of the earth 



AS GEOLOGIST 89 

from a chaotic to a more habitable state, nor of any law of 
progressive development governing the extinction and 
renovation of species, and causing the fauna and flora to 
pass from an embryonic to a more perfect condition, from a 
simple to a more complex organisation." It may have been 
allowable to say that no " law of progressive development " 
had been discovered, but of the fact that a striking pro- 
gressive advancement had taken place there could no 
longer be any doubt. 

53 Op. cit., first edition, Chap, ix., p. 148. 

54 Op. cit., ninth edition, Chap, ix., pp. 134 et seq. 

55 It is not always quite clear what "uniformity" 
implied in the creed of the uniformitarians. Lyell dis- 
claimed that he " contended for the absolute uniformity 
throughout all time of the succession of sublunary events " 
(Principles, ninth edit., p. 149). He insisted that "the 
order of nature has from the earliest periods been uniform 
in the same sense in which we believe it to be uniform at 
present, and expect it to remain so in future " (Ibid.}. But 
human experience embraced a mere fraction of geological 
time, and gave but a limited basis on which to determine 
what "the order of nature" is. It was this limitation 
which so roused the indignation of the Catastrophists. 
Lyell's own inclination evidently was against an admission 
that geological energy had ever been manifested on a more 
vigorous scale than has been witnessed by man. As he 
described himself, he was " a staunch advocate for absolute 
uniformity in the order of Nature" (Life, Letters and 
Journals of Sir Charles Lyell, Vol. I, p. 260). 

56 Principles of Geology, first edit., Vol. I, p. 124. This 
statement was repeated up to and including the ninth 
edition of the work. 



90 CHARLES DARWIN 

57 Lyell's Geological Evidences of the Antiquity of Man, 
with remarks on Theories of the Origin of Species by Vari- 
ation was published in 1863. It greatly disappointed 
Darwin with its halting language, when from their inter- 
course and discussions on the subject he had expected more 
decided support (Life and Letters, Vol. in, pp. 8 et seq). 
The tenth edition of the Principles of Geology appeared in 
two volumes, the first in 1867 and the second in 1868. The 
latter contained the author's full acceptance of Darwin's 
views. As Mr "Wallace truly remarked, "the history of 
science hardly presents so striking an instance of youthful- 
ness of mind in advanced life as is shown by this abandon- 
ment of opinions so long held and so powerfully advocated " 
(Quarterly Review, April, 1869). 

58 This thesis was maintained by Cuvier in his Theory 
of the Earth a work which went through many editions, 
and of which an English translation appeared under the 
editorship of Robert Jameson. Cuvier's great contemporary, 
Lamarck, on the other hand, disbelieved in the occasional 
catastrophes and re-creations which the former so confidently 
asserted. On the contrary, he looked on the succession of 
life as having probably been unbroken from the beginning, 
and he believed the existing faunas and floras of the globe 
to be the lineal descendants and representatives of other 
forms which have preceded them, and the remains of some 
of which have been preserved among the stratified rocks of 
the earth's crust. 

59 During his presidency of the Geological Society A. C. 
Ramsay gave from the chair two addresses (in 1863 and 
1864), wherein he discussed the character and meaning of 
what he called " breaks in succession " among the stratified 
formations of Britain, whether these interruptions are 



AS GEOLOGIST 91 

marked by unconformabilities or by abrupt changes in fossil 
contents. These brilliant addresses, printed in the Quarterly 
Journal of the Society, contained the first detailed and 
serious attempt to show the relative chronometric^ value of 
"breaks in succession," and gave strong support to the 
arguments maintained in the geological chapters of the 
Origin of Species. 



CAMBRIDGE : PRINTED BY JOHN CLAY, M.A. AT THE UNIVERSITY PRESS. 




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