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Vol. 38 No. 3–4

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Darwin and the geological

controversies over the steady-state

worldview in the 1830s

Gabriel Gohau

Centre Franc

¸ois

Viete, Universite de Nantes, 2 rue de la Houssiniere, 44 000 Nantes, France

In the ﬁrst part of this paper, I will show that although

Darwin’s geological works only covered the ﬁrst years of

his scientiﬁc career, these played a non-negligible role in

the earth sciences of the mid-nineteenth century. His

intellectual proximity with Charles Lyell often made him

his disciple. This is indeed the case with respect to debates

over ‘gradual’ soil movements and ‘catastrophic’ soil

movements, and for ‘steady-state’ cycles as opposed to

‘directionalistic’ ones. This being said, it is also true that in

South America Darwin saw geological processes which

were incompatible with Lyell’s explanations. It must there-

fore be recognized that Darwin held a middle-of-the-road

position between uniformitarianism (Lyell) and catastro-

phism (Humbolt and von Buch), at least as far as some

geological questions were concerned. In the second part of

the paper, debates on geological issues during Darwin’s

active years will be put in the methodological context of

the Scientiﬁc Revolution of the seventeenth century.

Introduction

Works by Charles Darwin are so varied we often forget that,

before being the author of books on such topics as barnacles

(cirripedia), orchids, expression of emotions, earthworms,

natural selection (On

the Origin of Species)

and human

evolution (The

Descent of Man),

he was actually a geologist.

After reading Sandra Herbert’s beautiful book one may well

ask: should Darwin have stuck with such a well-begun

geological career.

His works in the ﬁeld of geology after

his return from a ﬁve-year expedition on the

Beagle

are

conﬁned to the third volume of the

Beagle’s

Captain, Robert

FitzRoy, entitled

Narrative of the Surveying Voyages.

Dar-

win’s works are deployed in three distinct parts: (1) ‘The

structure and distribution of coral reefs’, 1842; (2) ‘Geological

observations on the volcanic islands

. . .

together with some

brief notices on the geology of Australia and the Cape of

Good Hope’, 1844; and (3) ‘Geological observations on South

Corresponding author:

Gohau, G. (ga.gohau@wanadoo.fr).

Gabriel Gohau, ‘Darwin the geologist. Between Lyell and von Buch. Darwin le

geologue. Entre Lyell et von Buch’,

Comptes Rendus Biologies,

333 (2010), 95–98.

Sandra Herbert,

Charles Darwin, Geologist

(Ithaca, 2005).

Charles Darwin, ‘Geological notes made during a survey of the East and West

Coasts of South America in the years 1832, 1833, 1834 and 1835, with an account of a

transverse section of the Cordilleras of the Andes between Valparaiso and Mendoza’,

Proceedings of the Geol. Soc of London,

vol. II, 1833–38, number 40 (1835), 210–212.

Available online 13 November 2014

America’, 1846. From November 1835,

Darwin also began

writing papers for the Geological Society of London. The

purpose of the present paper is to study the content of these

works, beginning with Lyell’s inﬂuence on Darwin, as well as

scholars like Herschel, von Buch, and Humboldt.

As is well-known, Darwin had with him on board the

Beagle

the ﬁrst volume of

Principles of Geology

published

by Charles Lyell in 1830 (Figure

1).

Captain FitzRoy was

particularly interested in geology, and he himself gave

Darwin a copy of Lyell’s ﬁrst volume.

During the voyage,

the young Darwin devoted most of his time and attention to

geology.

Before that voyage, the young man learned geol-

ogy through the lectures of Reverend Sedgwick at Cam-

bridge University. During the preceding months, he had

read Alexander Humboldt’s

Personal Narrative

and John

Herschel’s

Preliminary Discourse on the Study of Natural

Philosophy.

He was led to science by John Henslow, a

professor of botany, whom he later befriended and encour-

aged him to study geology with Sedgwick. During the

Summer of 1831, Darwin accompanied the famous geolo-

gist to Wales.

Henslow also encouraged him to study Lyell’s

book, but by no means accepted its point of view. Darwin,

however, rapidly became interested in Lyell’s approach,

which differed signiﬁcantly from that of Sedgwick. The

name for Lyell’s approach originates with William Whewell,

who in his review of the second volume of

Principles of

Geology

(1832) identiﬁed its essential characteristic as

one of ‘geological uniformity’: the process of slow and gradual

geological changes, opposing it to the reverse approach

which was, incidentally, that of Sedgwick and of many other

geologists. Whewell coined the name of ‘catastrophism’ to

refer to this latter approach.

By so doing, Whewell meant to

contrast progressive changes (uniform in their intensity)

to paroxysmal catastrophic changes.

Let us begin by examining Darwin’s own geological

observations, comparing them with those of his

Charles Darwin,

Voyage of the Beagle,

introduction by Janet Browne and Michael

Neve (London, 1989), 12.

Charles Darwin,

Geological Observations on South America,

Critical Introduction

by John W. Judd, 3rd ed. (London, 1890), 270.

Martin J.S. Rudwick,

Worlds before Adam: The Reconstriction of Geohistory in the

Age of Reform

(Chicago, 2008), 487.

William Whewell, ‘Review of Principles of Geology by C. Lyell’,

Quart. Review,

(1832), 126. Also, William Whewell,

History of the Inductive Sciences, from the Earliest to the

present Time,

2nd ed., Tome III (1847), The two antagonist doctrines of Geology, 658–677.

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http://dx.doi.org/10.1016/j.endeavour.2014.10.005

Endeavour

Vol. 38 No. 3–4

191

Figure 2.

Ring-shaped coral atoll illustrated in Charles Darwin’s

Structure and

Distribution of Coral Reefs,

2nd ed, Smith, Elder and Co, 1874. Photograph by

Patrice Maurin-Berthier.

during Darwin’s time and the Scientiﬁc Revolution, begun

several centuries before.

To what extent was Darwin Lyell’s disciple?

Vertical movements of the ground

Darwin witnessed ﬁrst-hand the earthquake that occurred

in Valdivia, Chile, on February 20, 1835. He noted a ground

elevation which, for him, was the cause of the earthquake.

He observed numerous marine remains then at 14,000 feet

above sea bottom level.

By chance, in the ﬁrst volume of

Lyell’s

Principles,

Darwin had actually read about the

1822 destructive earthquake on the Chilian coast.

In a

communication made to the Geological Society, dated Jan-

uary 4, 1837, Darwin noted the imperceptible rise of the

coast of Chile since 1822.

In Patagonia, he had already

observed the recent elevation of the whole coast to a

considerable height, and assumed that the successive ter-

races of the shores of the Paciﬁc had been formed recently

and very gradually.

Curiously, Lyell, who explained all

geological actions by causes now in operation (including

earthquakes and other natural catastrophes), rejected the

idea of a recent elevation in the Baltic area. In this partic-

ular respect, Darwin was more of a uniformitarian than

Lyell himself.

Similarly, Darwin assumed that the subsidence of coral

islands was a slow and continued process. For a long time,

travelers have been struck by the presence of lagoon

islands: an annular coral formation with a central lagoon,

isolated in the middle of the ocean (Figure

2).

Lyell, in his

Principles,

explained this simply: ‘they are

. . .

the crest of

submarine volcanoes, having the rims and bottoms of their

craters overgrown by corals’.

Darwin’s solution, however,

consisted in creating a link between coral formation and

the slow elevation of coasts. On his view, a crater was no

Charles Darwin,

loc.cit.

(London, 1989), 245. See also Charles Darwin, chap. VII

‘Central Chile—structure of the Cordillera’,

Geological observations on South America

(London, 1846).

Charles Lyell,

Principles of Geology. Being an Attempt to Explain the Former

Changes of the Earth’s Surface by Reference to Causes Now in Operation,

t I (London,

1830), 401–403.

Charles Darwin, ‘Observations of proofs of recent elevation on the coast of Chili,

made during the survey of his Majesty’s ship Beagle commanded by Capt. Fitzroy’,

Proceed. Geol. Soc. London,

II (1837), 448–449.

Ibid.,

159. See also

Geological Observations on South America,

chap. I and II, on

the elevation of the eastern and of the western coasts. And Sandra Herbert (Ithaca,

2005), 160 sqq.

Charles Lyell,

Op. cit.,

II (London, 1832), 290.

Figure 1.

Ruins of the Temple of Serapis in Rome, Italy. Frontispice of Charles

Lyell’s

Principles of Geology,

vol. 1, 1830. Photograph by Patrice Maurin-Berthier.

contemporaries. We shall see how the earlier observations

of Darwin supported the uniformitarian approach; we shall

also see, however, that a few of his other observations were

more in line with the opposing view. Despite being short,

Darwin’s geological career played a non-negligible role in

the controversies that shook the earth sciences in the

1830s. Indeed, it was his worldwide travel on the

Beagle

between 1831 and 1836 that allowed him to make this

contribution. In addition to Lyell’s

Principles of Geology,

from which Darwin adopted uniformitarianism, his

Beagle

readings also included works from catastrophist oppo-

nents, such as Humboldt. Darwin’s observation of disor-

dered layers of land in the Cordillera gave him the

opportunity to go beyond Lyell’s own explanation when

it came to the formation of mountain chains. It will be seen

that Darwin’s eclectic approach to geology can be seen in

three key issues, all founded on the principle of a cyclical,

eternal recurrence which accounts for the stability of fea-

tures observed on the earth’s surface:

(1) The vertical movements of the ground: upheavals and

subsidence

(2) Periodic climate change

(3) The problem of the formation of mountains

This paper will conclude with a section reﬂecting on the

intellectual relationships between the earth sciences

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192

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Vol. 38 No. 3–4

Figure 3.

Coral reef barrier illustrated in Charles Darwin’s

Structure and

Distribution of Coral Reefs,

2nd ed, Smith, Elder and Co, 1874. Photograph by

Patrice Maurin-Berthier.

longer necessary to explain the lagoon formation, as an

island which has its highest point at its center forms the

same lagoon (Figures

3 and 4).

Lyell eventually came to

accept Darwin’s point of view in the next editions of the

Principles,

perhaps unsurprisingly, since Darwin had pro-

duced an even more Lyellian theory about atolls than

Lyell’s own.

Reﬂecting upon these two sorts of movement, elevation

and subsidence, Darwin wrote: ‘when beholding more than

one hemisphere divided into symmetrical areas, which

within a limited period of time had undergone certain

known movements, we obtain some insight into the system

by which the crust of the globe is modiﬁed during the

endless cycle of changes’

[italics mine].

Here, Darwin

seems to subscribe to a steady-state view of geological

processes, just as Lyell had done before him:

There can be no doubt, that periods of disturbance

and repose have followed each other in succession in

every region of the globe, but it may be equally true,

that the energy of the subterraneous movements has

been always uniform as regards the

whole earth.

The

force of earthquakes (.

. .)

may then have gradually

shifted its position.

To more clearly deﬁne what seems to be a position

common to Darwin and Lyell with respect to the notion

of a steady-state worldview, a review of the two conﬂicting

theories (as they appeared in the 1830s) is here required.

Lyell’s uniformitarian thesis is rightly classiﬁed as

steady-

state,

according to Martin Rudwick’s terminology. In fact,

uniformitarianism

and

catastrophism,

the terms used by

Whewell, represent only one side (continuity) of Lyell’s

thesis. Rudwick commented on a letter from William Con-

ybeare (1787–1857) to Lyell, noting that:

. . .

it is perhaps unfortunate that Whewell should

have dubbed the opponents of uniformitarianism

‘catastrophists’ for sudden and violent geological

Charles Darwin, Voyage.

. .,

loc. Cit.,

chap. XXII, p. 333sq. Also ‘‘On certain areas of

elevation and subsidence in the Paciﬁc and Indian Oceans as deduced from the study

of Coral Formations’’,

Proceedings G. S. L.,

vol. II, 50 (1837), 552–554.

Charles Darwin, ‘‘On certain areas of elevation and subsidence in the Paciﬁc and

Indian oceans, as deduced from the study of Coral Formations",

Proceed. Geol. Soc.

London,

II 5 (1837) 554. See also

The structure and distribution of Coral Reefs, loc. cit.

(1842).

Charles Lyell,

Loc. cit.,

I (London, 1830), 64.

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Figure 4.

Geological process of erosion of a volcanic crater illustrated in Charles

Darwin’s

Structure and Distribution of Coral Reefs,

2nd ed, Smith, Elder and Co,

1874. Photograph by Patrice Maurin-Berthier.

events were not essential to their outlook. More

important was their conviction that the earth’s his-

tory comprised a sequence of unique events so that

each geological period represented a distinctive

phase in the earth’s development.

Rudwick ﬁnds particularly noteworthy the following

aspect of the letter: ‘Conybeare’s insistence that rival

models of earth history – historical and steady state –

lay at the root of the debate’.

A few years later, the

famous paleontologist George G. Simpson, declaring his

agreement with Rudwick, underscored that the disagree-

ment between Lyell and Conybeare – the archetypal uni-

formitarian and the catastrophist, respectively – ‘was not

in fact on the subject of catastrophe as usually understood,

but on that of a steady-state versus a historical model of

earth and life history’.

The terms ‘historical’ and ‘steady-

state’ coined in 1967 by Rudwick are now standard ele-

ments of scientiﬁc discourse: in fact, he borrowed the term

steady-state

from the vocabulary of astrophysicists.

Rud-

wick would use it again in 1971:

Martin J. S. Rudwick, ‘A Critique of Uniformitarian Geology. A letter from W.D.

Conybeare to Ch Lyell’,

Proceed American Phil Soc,

CXI (1967), 272–287, 272.

Ibid.,

273.

Ceorge G. Simpson,

loc.cit.

(Stroudsburg, 1975) 265.

Hermann Bondy and Thomas Gold, The steady-state theory of the expanding

Universe,

MNRAS,

vol. 108, 3 (1948), 252–270.

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Vol. 38 No. 3–4

193

I think we can identify four logical distinct types of

uniformity on this level (.

. .)

First there is the

theo-

logical status

of a past geological ‘cause’; in relation to

the creative activity of God (.

. .)

Second, there is the

methodological status

. .)

Thirdly, there is the

rate

which a geological ‘cause’ may be acted (.

. .)

Fourth

and last, there is the overall

pattern

of a past geologi-

cal ‘cause’, when its action is traced over the whole

known time-span of earth-history. It might be

steady-

state,

exhibiting relatively minor ﬂuctuations around

a constant mean; at least when the overall state of the

whole globe is taken into account. This is clearly the

original meaning of ‘uniformitarian’. Or the pattern

might be

directional,

or in more familiar terms ‘de-

velopmental’ or ‘progressive’, in that, underlying the

local ﬂuctuations in its activity, a general overall

trend can be detected on a global scale.

We can clearly understand how the term

catastrophism

does not adequately reﬂect Conybeare’s thinking. In deﬁn-

ing these terms, Whewell speaks of alternating periods of

disruption and periods of tranquility.

Continuity

and

steady-state

appear as two components not identical to

Lyell’s uniformitarianism. What makes the problem difﬁ-

cult is that authors such as Conybeare or Sedgwick (to

mention but two examples) who believe in the directional

evolution of the Earth do not preclude the possibility of

periodic variations (catastrophism) through the rare com-

bination of common physical causes. Nonetheless, Cony-

beare’s argument mainly focuses on directionalism. As

Rudwick says, the ‘historical picture of directional change

in the course of earth history is the most natural interpre-

tation of all the facts of geology and philosophically prefer-

able to Lyell’s uniformitarian model’.

On this understanding, it seems that Darwin and Lyell

are, indeed, united in the promotion of a somewhat mar-

ginal view called

steady-state geology,

a view opposed to

historicity or directionalism and founded on the notion of

relatively minor ﬂuctuations around a constant mean.

Climatic change

The ﬁrst problem concerned with the issue of climatic

change did not oppose Conybeare to Lyell. In his letter

of 1841, Conybeare writes: ‘I am a good deal caught by your

new articles on the causes of changes of temperature in

geological periods’.

Nevertheless, mountains which bear

traces of land modiﬁcations (erratic boulders carried to

plains) are proof of forces which do not exist in nature

today. This constitutes a key argument on the side of

catastrophism. Catastrophists invoked more intense forces

only because presently observable streams were not capa-

ble of eroding valleys, which have been cut out by ancient

glaciers.

Interestingly, Darwin also adopted this theory:

erratic boulders could not be explained without referring to

ice movement. Darwin’s mistake, however, was to base this

Martin J. S. Rudwick, ‘Uniformity and Progression: Reﬂections on the Structure of

Geological theory in the Age of Lyell’, in D.H.D. Roller (ed.),

Perspectives in the History

of Science and Technology

(Norman, 1971), 209–227, 211–212.

Ibid.,

279.

Rudwick,

loc. cit.

1967, p. 279.

Gordon. L. Davies,

The Earth in Decay. A History of British Geomorphology,

1578 to 1878,

chap. 8 (Amsterdam, London, 1969), 263 sq.

www.sciencedirect.com

theory on sea-ice forming icebergs rather than on conti-

nental glaciers.

On that speciﬁc issue, Darwin shared

Lyell’s viewpoint, who eventually came to accept the gla-

cial theory but only after prolonged resistance to the idea.

This being said, Darwin’s position against continental

glaciers led him to a grave error: the problem of Glen Roy.

The case began during the voyage of the

Beagle.

In the

3rd volume of the

Principles of Geology

(1833), Lyell held

that parallel roads observed in Coquimbo (Chile) consti-

tuted ancient marine beaches, noting the existence of

analogous parallel roads in Glen Road, Scotland.

During

the

Beagle

voyage, in May 1835, Darwin visited Coquimbo

and commented as follows:

I spent two or three days in examining the step-

formed terraces of shingle ﬁrst described by captain

Basil Hall, in his work, so full of spirited descriptions,

in the west coast of America. Mr. Lyell concluded

from the account, that they must have been formed by

the sea during the gradual rising of the land. Such is

the case: on some of the steps which sweep round

from within the valley, so as to front the coast, shells

of existing species both lie on the surface, and are

embedded in a soft calcareous stone. This bed of the

most modern tertiary epoch passes downward into

another, containing some living species associated

with others now lost. Amongst the latter may be

mentioned shells of an enormous perna and an oys-

ter, and the teeth of a gigantic shark, closely allied to,

or identical with the Carchiarias Megalodon of an-

cient Europe.

Yet, two independent observers of the Glen Roy forma-

tion, MacCulloch, in 1816 (published in 1817) and Lauder,

in 1821 (published in 1823) concluded that the parallel

roads were in reality lake beaches and not marine beaches.

Only after his return to England did Darwin visit Glen Roy,

from June 28th to July 5th, 1838. His observations there

about the ‘buttresses of alluvium’ seen at the upper end of

the neighboring lake (Loch Dochart)

prompted him to

conclude that ‘Rivers could not have deposited it. Barrier of

lake very lofty, & no trace of it; to the Sea more probable’.

Unfortunately for Darwin, Louis Agassiz (1807–1873)

would establish two years later that the roads were of

glacial origin. Martin Rudwick

and Sandra Herbert

have reconstituted the controversy. The ﬁnal solution

eventually came from Jamieson, who visited Glen Roy in

1861:

Jamieson concluded that both lack of good and posi-

tive evidence in favour of the marine hypothesis and

availability of such evidence in favour of Agassiz

Charles Darwin, ‘On the distribution of the Erratic Boulders and on the contem-

poraneous unstratiﬁed Deposits of South America’,

Proceed. Geol. Soc. London,

III

(1842), 425–430. See also

Transactions of the G. S. L.,

(2), vol. VI (1841), 415–431.

Gordon L. Davies,

loc. cit.

(Amsterdam, London, 1969), p. 286 sq.

Charles Lyell,

loc. cit.,

III (London, 1833), 131.

Charles Darwin,

loc. cit.

(London, 1989), 261.

Charles Darwin, ‘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’,

Philosophical Transactions of the Royal Society of London

(1839), 39–81.

Sandra Herbert,

loc. cit.

(Ithaca, 2005), 266.

Martin Rudwick, ‘Darwin and Glen Roy. A ‘Great Failure’ in Scientiﬁc Method’,

Studies in Hist. and Phil. of Science,

5 (1974), 97–185.

Sandra Herbert,

loc. cit.

(Ithaca, 2005), 262 sq.

194

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Vol. 38 No. 3–4

hypothesis rendered Darwin’s theory completely un-

tenable (.

. .)

Two decades later Darwin recalled that

. .)

he ‘had given up the ghost with more sighs and

groans than on almost any other occasion in [his]

life’.

The change in temperature implied by the Glen Roy

geological formation was, however, hotly debated at the

time. The majority of geologists then believed that the

temperature of the Earth had gradually decreased since

its formation, when the Earth was an igneous body as-

sumed to have originated from the primitive nebula at the

origin of our solar system, and for which the model had

been provided by the calculations of Joseph Fourier (1824).

This hypothesis was supported by the elevation of temper-

ature observed in deep mines (Cordier 1827). Lyell, how-

ever, objected:

. . .

all this is precisely what we should have

expected to arise from variations in the intensity

of volcanic heat, and from that change of position,

which the principal theatres of volcanic action have

undergone at different periods, as the geologist can

distinctly prove. But M. Cordier conjectures that

there is a connection between such phenomena and

the secular refrigeration and contraction of the

internal ﬂuid mass, and that the change of climate,

of which there are geological proofs, favour this

hypothesis.

In Lyell’s view, ceaseless changes in the distribution of

land and sea have been the norm everywhere, and have

provoked continual ﬂuctuations in the mean tempera-

ture.

As Rudwick puts it, ‘[Lyell] suggests that the global

climate might oscillate between what he terms metaphori-

cally the ‘‘winter’’ and ‘‘summer’’ of the ‘‘great year’’’.

have seen that Darwin had reluctantly given up on some

empirical facts supporting the interpretation of a steady-

state view at Glen Roy.

Mountain building

The major geological problem of the

Beagle’s

voyage for

Darwin was the explanation of mountain building

(Figure

5).

The elevation of the Andes was the most recent

episode of this phenomenon, according to Elie de Beau-

mont. By chance, Darwin was in the area and he was more

impressed by the elevation than by the folds. Indeed, it

was easier for a uniformitarian to explain an elevation by a

gradual movement than by a shortening of crust (folding).

During his travel in the Cordillera, he observed a ‘great

pile of strata (.

. .)

penetrated, upheaved, and overturned,

in the most extraordinary manner, by masses of injected

rock, equaling mountains in size’.

In a communication to

the Geological Society, Darwin claimed that ‘the conclu-

sion that mountain-chains are formed by a long succession

of small movements, may, as it appears to me, be rendered

Narasimhan M. G., ‘Controversy in science’,

Journal of Biosciences,

26, 3 (2001),

299–304.

Charles Lyell,

Op. cit.,

t.I (London, 1830), 142–143.

Ibid.,

115.

Martin Rudwick,

loc.cit.

(Chicago, 1990), XXI.

Charles Darwin,

loc. cit.

(London, 1989), 245.

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Figure 5.

Graphics theorizing the lift of mountain chains in Charles Darwin’s

‘‘On the Connexion of Certain Volcanic Phenomena in South America

. . .’’,

appearing in the

Transactions of the Geological Society of London,

(2), V, 1840, p.

625. Photograph by Patrice Maurin-Berthier.

also probable by simple theoretical reasoning’.

added: ‘We shall be deeply impressed with the grandeur

of the one motive power, which, causing the elevation of

the continent, has produced, as secondary effects, moun-

tain-chains and volcanoes’.

When he explains earth-

quakes in South America by ‘the interjection of liqueﬁed

rocks between masses of strata’,

‘proving by their inter-

sections, successive periods of violence

. . .

[along] great

lines of dislocation’,

he is closer to catastrophic theories

of von Buch and Humboldt than to the uniformitarism of

Charles Lyell. Following the thesis of these former

authors, Darwin thought that St Helena and other such

islands were craters of elevation.

Simultaneously, how-

ever, Darwin adopted Lyell’s idea of metamorphic actions

on those geological formations.

A question is worth been raised here: can mountain

building be entirely explained using only Charles Lyell’s

theory? It is difﬁcult to subscribe to a positive answer. In

fact, mountain formation remained difﬁcult to explain for

Charles Darwin, ‘On the Connexion of certain Volcanic Phenomena in South

America; and the Formation of Mountain Chains and Volcanos, as the Effect of the

same Power by which Continents are elevated’,

Trans. Geol. Soc. London,

(2), V,

(1840), 601–631, at 625. See also S. Herbert,

loc. cit.

(2005), 225–230, and particularly,

228, a ﬁgure showing Hopkin’s sketches.

Ibid.,

630.

Ibid.,

615.

Charles Darwin,

loc. cit.

(London, 1989), 245.

Charles Darwin,

Geological Observations on the Volcanic Islands.

. .

(London,

1844), 93–96. Also Sandra Herbert,

loc. cit.,

(Ithaca, 2005), 241–242.

Voyage, loc. cit.,

245. Also

Geological Observations in South America, loc. cit.,

(London, 1846), chapter VI plutonic and metamorphic rocks—cleavage and foliation.

On Darwin, Buch and Humboldt, see Sandra Herbert,

loc. cit,

(Ithaca, 2005), 13–17,

58, 125, 141, 167, 198, 248. Particularly 198 sq.

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