Part 3 out of 14
LETTER 468. TO W. OGLE.
Down, March 7th .
I wrote to Tyndall, but had no clear answer, and have now written to him
again about odours. (468/1. Dr. Ogle's work on the Sense of Smell
("Medico-Chirurgical Trans." LIII., page 268) is referred to in the
"Expression of the Emotions," page 256.) I write now to ask you to be so
kind (if there is no objection) to tell me the circumstances under which
you saw a man arrested for murder. (468/2. Given in the "Expression of
the Emotions," page 294.) I say in my notes made from your conversation:
utmost horror--extreme pallor--mouth relaxed and open--general prostration
--perspiration--muscle of face contracted--hair observed on account of
having been dyed, and apparently not erected. Secondly, may I quote you
that you have often (?) seen persons (young or old? men or women?) who,
evincing no great fear, were about to undergo severe operation under
chloroform, showing resignation by (alternately?) folding one open hand
over the other on the lower part of chest (whilst recumbent?)--I know this
expression, and think I ought to notice it. Could you look out for an
I fear you will think me very troublesome, especially when I remind you
(not that I am in a hurry) about the Eustachian tube.
LETTER 469. TO J. JENNER WEIR.
Down, June 14th .
As usual, I am going to beg for information. Can you tell me whether any
Fringillidae or Sylviadae erect their feathers when frightened or enraged?
(469/1. See "Expression of the Emotions," page 99.) I want to show that
this expression is common to all or most of the families of birds. I know
of this only in the fowl, swan, tropic-bird, owl, ruff and reeve, and
cuckoo. I fancy that I remember having seen nestling birds erect their
feathers greatly when looking into nests, as is said to be the case with
young cuckoos. I should much like to know whether nestlings do really thus
erect their feathers. I am now at work on expression in animals of all
kinds, and birds; and if you have any hints I should be very glad for them,
and you have a rich wealth of facts of all kinds. Any cases like the
following: the sheldrake pats or dances on the tidal sands to make the
sea-worms come out; and when Mr. St. John's tame sheldrakes came to ask for
their dinners they used to pat the ground, and this I should call an
expression of hunger and impatience. How about the Quagga case? (469/2.
See Letter 235, Volume I.)
I am working away as hard as I can on my book; but good heavens, how slow
my progress is.
LETTER 470. TO F.C. DONDERS.
Down, March 18th, 1871.
Very many thanks for your kind letter. I have been interested by what you
tell me about your views published in 1848, and I wish I could read your
essay. It is clear to me that you were as near as possible in preceding me
on the subject of Natural Selection.
You will find very little that is new to you in my last book; whatever
merit it may possess consists in the grouping of the facts and in
deductions from them. I am now at work on my essay on Expression. My last
book fatigued me much, and I have had much correspondence, otherwise I
should have written to you long ago, as I often intended to tell you in how
high a degree your essay published in Beale's Archives interested me.
(470/1. Beale's "Archives of Medicine," Volume V., 1870.) I have heard
others express their admiration at the complete manner in which you have
treated the subject. Your confirmation of Sir C. Bell's rather loose
statement has been of paramount importance for my work. (470/2. On the
contraction of the muscles surrounding the eye. See "Expression of the
Emotions," page 158. See Letters 464, 465.) You told me that I might make
further enquiries from you.
When a person is lost in meditation his eyes often appear as if fixed on a
distant object (470/3. The appearance is due to divergence of the lines of
vision produced by muscular relaxation. See "Expression of the Emotions,"
Edition II., page 239.), and the lower eyelids may be seen to contract and
become wrinkled. I suppose the idea is quite fanciful, but as you say that
the eyeball advances in adaptation for vision for close objects, would the
eyeball have to be pushed backwards in adaptation for distant objects?
(470/4. Darwin seems to have misunderstood a remark of Donders.) If so,
can the wrinkling of the lower eyelids, which has often perplexed me, act
in pushing back the eyeball?
But, as I have said, I daresay this is quite fanciful. Gratiolet says that
the pupil contracts in rage, and dilates enormously in terror. (470/5.
See "Expression of the Emotions," Edition II., page 321.) I have not found
this great anatomist quite trustworthy on such points, and am making
enquiries on this subject. But I am inclined to believe him, as the old
Scotch anatomist Munro says, that the iris of parrots contracts and dilates
under passions, independently of the amount of light. Can you give any
explanation of this statement? When the heart beats hard and quick, and
the head becomes somewhat congested with blood in any illness, does the
pupil contract? Does the pupil dilate in incipient faintness, or in utter
prostration, as when after a severe race a man is pallid, bathed in
perspiration, with all his muscles quivering? Or in extreme prostration
from any illness?
LETTER 471. TO W. TURNER.
Down, March 28th .
I am much obliged for your kind note, and especially for your offer of
sending me some time corrections, for which I shall be truly grateful. I
know that there are many blunders to which I am very liable. There is a
terrible one confusing the supra-condyloid foramen with another one.
(471/1. In the first edition of the "Descent of Man," I., page 28, in
quoting Mr. Busk "On the Caves of Gibraltar," Mr. Darwin confuses together
the inter-condyloid foramen in the humerus with the supra-condyloid
foramen. His attention was called to the mistake by Sir William Turner, to
whom he had been previously indebted for other information on the anatomy
of man. The error is one, as Sir William Turner points out in a letter,
"which might easily arise where the writer is not minutely acquainted with
human anatomy." In speaking of his correspondence with Darwin, Sir William
remarks on a characteristic of Darwin's method of asking for information,
namely, his care in avoiding leading questions.) This, however, I have
corrected in all the copies struck off after the first lot of 2500. I
daresay there will be a new edition in the course of nine months or a year,
and this I will correct as well as I can. As yet the publishers have kept
up type, and grumble dreadfully if I make heavy corrections. I am very far
from surprised that "you have not committed yourself to full acceptation"
of the evolution of man. Difficulties and objections there undoubtedly
are, enough and to spare, to stagger any cautious man who has much
knowledge like yourself.
I am now at work at my hobby-horse essay on Expression, and I have been
reading some old notes of yours. In one you say it is easy to see that the
spines of the hedgehog are moved by the voluntary panniculus. Now, can you
tell me whether each spine has likewise an oblique unstriped or striped
muscle, as figured by Lister? (472/2. "Expression of the Emotions," page
101.) Do you know whether the tail-coverts of peacock or tail of turkey
are erected by unstriped or striped muscles, and whether these are
homologous with the panniculus or with the single oblique unstriped muscles
going to each separate hair in man and many animals? I wrote some time ago
to Kolliker to ask this question (and in relation to quills of porcupine),
and I received a long and interesting letter, but he could not answer these
questions. If I do not receive any answer (for I know how busy you must
be), I will understand you cannot aid me.
I heard yesterday that Paget was very ill; I hope this is not true. What a
loss he would be; he is so charming a man.
P.S.--As I am writing I will trouble you with one other question. Have you
seen anything or read of any facts which could induce you to think that the
mind being intently and long directed to any portion of the skin (or,
indeed, any organ) would influence the action of the capillaries, causing
them either to contract or dilate? Any information on this head would be
of great value to me, as bearing on blushing.
If I remember right, Paget seems to be a great believer in the influence of
the mind in the nutrition of parts, and even in causing disease. It is
awfully audacious on my part, but I remember thinking (with respect to the
latter assertion on disease) when I read the passage that it seemed rather
fanciful, though I should like to believe in it. Sir H. Holland alludes to
this subject of the influence of the mind on local circulation frequently,
but gives no clear evidence. (472/3. Ibid., pages 339 et seq.)
LETTER 472. TO W. TURNER.
Down, March 29th .
Forgive me for troubling you with one line. Since writing my P.S. I have
read the part on the influence of the nervous system on the nutrition of
parts in your last edition of Paget's "Lectures." (472/1. "Lectures on
Surgical Pathology," Edition III., revised by Professor Turner, 1870.) I
had not read before this part in this edition, and I see how foolish I was.
But still, I should be extremely grateful for any hint or evidence of the
influence of mental attention on the capillary or local circulation of the
skin, or of any part to which the mind may be intently and long directed.
For instance, if thinking intently about a local eruption on the skin (not
on the face, for shame might possibly intervene) caused it temporarily to
redden, or thinking of a tumour caused it to throb, independently of
increased heart action.
LETTER 473. TO HUBERT AIRY.
(473/1. Dr. Airy had written to Mr. Darwin on April 3rd:--
"With regard to the loss of voluntary movement of the ears in man and
monkey, may I ask if you do not think it might have been caused, as it is
certainly compensated, by the facility and quickness in turning the head,
possessed by them in virtue of their more erect stature, and the freedom of
the atlanto-axial articulation? (in birds the same end is gained by the
length and flexibility of the neck.) The importance, in case of danger, of
bringing the eyes to help the ears would call for a quick turn of the head
whenever a new sound was heard, and so would tend to make superfluous any
special means of moving the ears, except in the case of quadrupeds and the
like, that have great trouble (comparatively speaking) in making a
horizontal turn of the head--can only do it by a slow bend of the whole
neck." (473/2. We are indebted to Dr. Airy for furnishing us with a copy
of his letter to Mr. Darwin, the original of which had been mislaid.)
Down, April 5th .
I am greatly obliged for your letter. Your idea about the easy turning of
the head instead of the ears themselves strikes me as very good, and quite
new to me, and I will keep it in mind; but I fear that there are some cases
opposed to the notion.
If I remember right the hedgehog has very human ears, but birds support
your view, though lizards are opposed to it.
Several persons have pointed out my error about the platysma. (473/3. The
error in question occurs on page 19 of the "Descent of Man," Edition I.,
where it is stated that the Platysma myoides cannot be voluntarily brought
into action. In the "Expression of the Emotions" Darwin remarks that this
muscle is sometimes said not to be under voluntary control, and he shows
that this is not universally true.) Nor can I remember how I was misled.
I find I can act on this muscle myself, now that I know the corners of the
mouth have to be drawn back. I know of the case of a man who can act on
this muscle on one side, but not on the other; yet he asserts positively
that both contract when he is startled. And this leads me to ask you to be
so kind as to observe, if any opportunity should occur, whether the
platysma contracts during extreme terror, as before an operation; and
secondly, whether it contracts during a shivering fit. Several persons are
observing for me, but I receive most discordant results.
I beg you to present my most respectful and kind compliments to your
honoured father [Sir G.B. Airy].
LETTER 474. TO FRANCIS GALTON.
(474/1. Mr. Galton had written on November 7th, 1872, offering to send to
various parts of Africa Darwin's printed list of questions intended to
guide observers on expression. Mr. Galton goes on: "You do not, I think,
mention in "Expression" what I thought was universal among blubbering
children (when not trying to see if harm or help was coming out of the
corner of one eye) of pressing the knuckles against the eyeballs, thereby
reinforcing the orbicularis.")
Down, November 8th .
Many thanks for your note and offer to send out the queries; but my career
is so nearly closed that I do not think it worth while. What little more I
can do shall be chiefly new work. I ought to have thought of crying
children rubbing their eyes with their knuckles, but I did not think of it,
and cannot explain it. As far as my memory serves, they do not do so
whilst roaring, in which case compression would be of use. I think it is
at the close of the crying fit, as if they wished to stop their eyes
crying, or possibly to relieve the irritation from the salt tears. I wish
I knew more about the knuckles and crying.
What a tremendous stir-up your excellent article on prayer has made in
England and America! (474/2. The article entitled "Statistical Inquiries
into the Efficacy of Prayer" appeared in the "Fortnightly Review," 1872.
In Mr. Francis Galton's book on "Enquiries into Human Faculty and its
Development," London, 1883, a section (pages 277-94) is devoted to a
discussion on the "Objective Efficacy of Prayer.")
LETTER 475. TO F.C. DONDERS.
(475/1. We have no means of knowing whether the observations suggested in
the following letter were made--if not, the suggestion is worthy of
Down, December 21st, 1872.
You will have received some little time ago my book on Expression, in
writing which I was so deeply indebted to your kindness. I want now to beg
a favour of you, if you have the means to grant it. A clergyman, the head
of an institution for the blind in England (475/2. The Rev. R.H. Blair,
Principal of the Worcester College: "Expression of the Emotions," Edition
II., page 237.), has been observing the expression of those born blind, and
he informs me that they never or very rarely frown. He kept a record of
several cases, but at last observed a frown on two of the children who he
thought never frowned; and then in a foolish manner tore up his notes, and
did not write to me until my book was published. He may be a bad observer
and altogether mistaken, but I think it would be worth while to ascertain
whether those born blind, when young, and whilst screaming violently,
contract the muscles round the eyes like ordinary infants. And secondly,
whether in after years they rarely or never frown. If it should prove true
that infants born blind do not contract their orbicular muscles whilst
screaming (though I can hardly believe it) it would be interesting to know
whether they shed tears as copiously as other children. The nature of the
affection which causes blindness may possibly influence the contraction of
the muscles, but on all such points you will judge infinitely better than I
can. Perhaps you could get some trustworthy superintendent of an asylum
for the blind to attend to this subject. I am sure that you will forgive
me asking this favour.
LETTER 476. TO D. HACK TUKE.
Down, December 22nd, 1872.
I have now finished your book, and have read it with great interest.
(476/1. "Influence of the Mind upon the Body. Designed to elucidate the
Power of the Imagination." 1872.)
Many of your cases are very striking. As I felt sure would be the case, I
have learnt much from it; and I should have modified several passages in my
book on Expression, if I had had the advantage of reading your work before
my publication. I always felt, and said so a year ago to Professor
Donders, that I had not sufficient knowledge of Physiology to treat my
subject in a proper way.
With many thanks for the interest which I have felt in reading your work...
LETTER 477. TO A.R. WALLACE.
Down, January 10th .
I have read your Review with much interest, and I thank you sincerely for
the very kind spirit in which it is written. I cannot say that I am
convinced by your criticisms. (477/1. "Quarterly Journal of Science,"
January, 1873, page 116: "I can hardly believe that when a cat, lying on a
shawl or other soft material, pats or pounds it with its feet, or sometimes
sucks a piece of it, it is the persistence of the habit of pressing the
mammary glands and sucking during kittenhood." Mr. Wallace goes on to say
that infantine habits are generally completely lost in adult life, and that
it seems unlikely that they should persist in a few isolated instances.)
If you have ever actually observed a kitten sucking and pounding, with
extended toes, its mother, and then seen the same kitten when a little
older doing the same thing on a soft shawl, and ultimately an old cat (as I
have seen), and do not admit that it is identically the same action, I am
astonished. With respect to the decapitated frog, I have always heard of
Pfluger as a most trustworthy observer. (477/2. Mr. Wallace speaks of "a
readiness to accept the most marvellous conclusions or interpretations of
physiologists on what seem very insufficient grounds," and he goes on to
assert that the frog experiment is either incorrectly recorded or else that
it "demonstrates volition, and not reflex action.") If, indeed, any one
knows a frog's habits so well as to say that it never rubs off a bit of
leaf or other object which may stick to its thigh, in the same manner as it
did the acid, your objection would be valid. Some of Flourens'
experiments, in which he removed the cerebral hemispheres from a pigeon,
indicate that acts apparently performed consciously can be done without
consciousness. I presume through the force of habit, in which case it
would appear that intellectual power is not brought into play. Several
persons have made suggestions and objections as yours about the hands being
held up in astonishment; if there was any straining of the muscles, as with
protruded arms under fright, I would agree; as it is I must keep to my old
opinion, and I dare say you will say that I am an obstinate old blockhead.
(477/3. The raising of the hands in surprise is explained ("Expression of
Emotions," Edition I., page 287) on the doctrine of antithesis as being the
opposite of listlessness. Mr. Wallace's view (given in the 2nd edition of
"Expression of the Emotions," page 300) is that the gesture is appropriate
to sudden defence or to the giving of aid to another person.)
The book has sold wonderfully; 9,000 copies have now been printed.
LETTER 478. TO CHAUNCEY WRIGHT.
Down, September 21st, 1874.
I have read your long letter with the greatest interest, and it was
extremely kind of you to take such great trouble. Now that you call my
attention to the fact, I well know the appearance of persons moving the
head from side to side when critically viewing any object; and I am almost
sure that I have seen the same gesture in an affected person when speaking
in exaggerated terms of some beautiful object not present. I should think
your explanation of this gesture was the true one. But there seems to me a
rather wide difference between inclining or moving the head laterally, and
moving it in the same plane, as we do in negation, and, as you truly add,
in disapprobation. It may, however, be that these two movements of the
head have been confounded by travellers when speaking of the Turks.
Perhaps Prof. Lowell would remember whether the movement was identically
the same. Your remarks on the effects of viewing a sunset, etc., with the
head inverted are very curious. (478/1. The letter dated September 3rd,
1874, is published in Mr. Thayer's "Letters" of Chauncey Wright, privately
printed, Cambridge, Mass., 1878. Wright quotes Mr. Sophocles, a native of
Greece, at the time Professor of Modern and Ancient Greek at Harvard
University, to the effect that the Turks do not express affirmation by a
shake of the head, but by a bow or grave nod, negation being expressed by a
backward nod. From the striking effect produced by looking at a landscape
with the head inverted, or by looking at its reflection, Chauncey Wright
was led to the lateral movement of the head, which is characteristic of
critical inspection--eg. of a picture. He thinks that in this way a
gesture of deliberative assent arose which may have been confused with our
ordinary sign of negation. He thus attempts to account for the
contradictions between Lieber's statement that a Turk or Greek expresses
"yes" by a shake of the head, and the opposite opinion of Prof. Sophocles,
and lastly, Mr. Lowell's assertion that in Italy our negative shake of the
head is used in affirmation (see "Expression of the Emotions," Edition II.,
page 289).) We have a looking-glass in the drawing-room opposite the
flower-garden, and I have often been struck how extremely pretty and
strange the flower garden and surrounding bushes appear when thus viewed.
Your letter will be very useful to me for a new edition of my Expression
book; but this will not be for a long time, if ever, as the publisher was
misled by the very large sale at first, and printed far too many copies.
I daresay you intend to publish your views in some essay, and I think you
ought to do so, for you might make an interesting and instructive
I have been half killing myself of late with microscopical work on plants.
I begin to think that they are more wonderful than animals.
P.S., January 29th, 1875.--You will see that by a stupid mistake in the
address this letter has just been returned to me. It is by no means worth
forwarding, but I cannot bear that you should think me so ungracious and
ungrateful as not to have thanked you for your long letter.
As I forget whether "Cambridge" is sufficient address, I will send this
through Asa Gray.
(PLATE: CHARLES LYELL. Engraved by G.I. (J). Stodart from a photograph.)
CHAPTER 2.IX. GEOLOGY, 1840-1882.
I. Vulcanicity and Earth-movements.--II. Ice-action.--III. The Parallel
Roads of Glen Roy.--IV. Coral Reefs, Fossil and Recent.--V. Cleavage and
Foliation.--VI. Age of the World.--VII. Geological Action of Earthworms.
2.IX.I. VULCANICITY AND EARTH-MOVEMENTS, 1840-1881.
LETTER 479. TO DAVID MILNE.
12, Upper Gower Street, Thursday [March] 20th .
I much regret that I am unable to give you any information of the kind you
desire. You must have misunderstood Mr. Lyell concerning the object of my
paper. (479/1. "On the Connexion of certain Volcanic Phenomena, and on
the Formation of Mountain-chains and the Effects of Continental
Elevations." "Trans. Geol. Soc." Volume V., 1840, pages 601-32 [March 7th,
1838].) It is an account of the shock of February, 1835, in Chile, which
is particularly interesting, as it ties most closely together volcanic
eruptions and continental elevations. In that paper I notice a very
remarkable coincidence in volcanic eruptions in S. America at very distant
places. I have also drawn up some short tables showing, as it appears to
me, that there are periods of unusually great volcanic activity affecting
large portions of S. America. I have no record of any coincidences between
shocks there and in Europe. Humboldt, by his table in the "Pers.
Narrative" (Volume IV., page 36, English Translation), seems to consider
the elevation of Sabrina off the Azores as connected with S. American
subterranean activity: this connection appears to be exceedingly vague. I
have during the past year seen it stated that a severe shock in the
northern parts of S. America coincided with one in Kamstchatka. Believing,
then, that such coincidences are purely accidental, I neglected to take a
note of the reference; but I believe the statement was somewhere in
"L'Institut" for 1839. (479/2. "L'Institut, Journal General des Societes
et Travaux Scientifiques de la France et de l'Etranger," Tome VIII. page
412, Paris, 1840. In a note on some earthquakes in the province Maurienne
it is stated that they occurred during a change in the weather, and at
times when a south wind followed a north wind, etc.) I was myself anxious
to see the list of the 1200 shocks alluded to by you, but I have not been
able to find out that the list has been published. With respect to any
coincidences you may discover between shocks in S. America and Europe, let
me venture to suggest to you that it is probably a quite accurate statement
that scarcely one hour in the year elapses in S. America without an
accompanying shock in some part of that large continent. There are many
regions in which earthquakes take place every three and four days; and
after the severer shocks the ground trembles almost half-hourly for months.
If, therefore, you had a list of the earthquakes of two or three of these
districts, it is almost certain that some of them would coincide with those
in Scotland, without any other connection than mere chance.
My paper will be published immediately in the "Geological Transactions,"
and I will do myself the pleasure of sending you a copy in the course of
(as I hope) a week or ten days. A large part of it is theoretical, and
will be of little interest to you; but the account of the Concepcion shock
of 1835 will, I think, be worth your perusal. I have understood from Mr.
Lyell that you believe in some connection between the state of the weather
and earthquakes. Under the very peculiar climate of Northern Chile, the
belief of the inhabitants in such connection can hardly, in my opinion, be
founded in error. It must possibly be worth your while to turn to pages
430-433 in my "Journal of Researches during the Voyage of the 'Beagle',"
where I have stated this circumstance. (479/3. "Journal of Researches
into the Natural History and Geology of the Countries visited during the
Voyage of H.M.S. 'Beagle' round the World." London, 1870, page 351.) On
the hypothesis of the crust of the earth resting on fluid matter, would the
influence of the moon (as indexed by the tides) affect the periods of the
shocks, when the force which causes them is just balanced by the resistance
of the solid crust? The fact you mention of the coincidence between the
earthquakes of Calabria and Scotland appears most curious. Your paper will
possess a high degree of interest to all geologists. I fancied that such
uniformity of action, as seems here indicated, was probably confined to
large continents, such as the Americas. How interesting a record of
volcanic phenomena in Iceland would be, now that you are collecting
accounts of every slight trembling in Scotland. I am astonished at their
frequency in that quiet country, as any one would have called it. I wish
it had been in my power to have contributed in any way to your researches
on this most interesting subject.
LETTER 480. TO L. HORNER.
Down, August 29th .
I am greatly obliged for your kind note, and much pleased with its
contents. If one-third of what you say be really true, and not the verdict
of a partial judge (as from pleasant experience I much suspect), then
should I be thoroughly well contented with my small volume which, small as
it is, cost me much time. (480/1. "Geological Observations on the
Volcanic Islands visited during the Voyage of H.M.S. 'Beagle'": London,
1844. A French translation has been made by Professor Renard of Ghent, and
published by Reinwald of Paris in 1902.) The pleasure of observation amply
repays itself: not so that of composition; and it requires the hope of
some small degree of utility in the end to make up for the drudgery of
altering bad English into sometimes a little better and sometimes worse.
With respect to craters of elevation (480/2. "Geological Observations,"
pages 93-6.), I had no sooner printed off the few pages on that subject
than I wished the whole erased. I utterly disbelieve in Von Buch and de
Beaumont's views; but on the other hand, in the case of the Mauritius and
St. Jago, I cannot, perhaps unphilosophically, persuade myself that they
are merely the basal fragments of ordinary volcanoes; and therefore I
thought I would suggest the notion of a slow circumferential elevation, the
central part being left unelevated, owing to the force from below being
spent and [relieved?] in eruptions. On this view, I do not consider these
so-called craters of elevation as formed by the ejection of ashes, lava,
etc., etc., but by a peculiar kind of elevation acting round and modified
by a volcanic orifice. I wish I had left it all out; I trust that there
are in other parts of the volume more facts and less theory. The more I
reflect on volcanoes, the more I appreciate the importance of E. de
Beaumont's measurements (480/3. Elie de Beaumont's views are discussed by
Sir Charles Lyell both in the "Principles of Geology" (Edition X., 1867,
Volume I. pages 633 et seq.) and in the "Elements of Geology" (Edition
III., 1878, pages 495, 496). See also Darwin's "Geological Observations,"
Edition II., 1876, page 107.) (even if one does not believe them
implicitly) of the natural inclination of lava-streams, and even more the
importance of his view of the dikes, or unfilled fissures, in every
volcanic mountain, being the proofs and measures of the stretching and
consequent elevation which all such mountains must have undergone. I
believe he thus unintentionally explains most of his cases of lava-streams
being inclined at a greater angle than that at which they could have
But excuse this lengthy note, and once more let me thank you for the
pleasure and encouragement you have given me--which, together with Lyell's
never-failing kindness, will help me on with South America, and, as my
books will not sell, I sometimes want such aid. I have been lately reading
with care A. d'Orbigny's work on South America (480/4. "Voyage dans
l'Amerique Meridionale--execute pendant les annees 1826-33": six volumes,
Paris, 1835-43.), and I cannot say how forcibly impressed I am with the
infinite superiority of the Lyellian school of Geology over the
continental. I always feel as if my books came half out of Lyell's brain,
and that I never acknowledge this sufficiently; nor do I know how I can
without saying so in so many words--for I have always thought that the
great merit of the "Principles" was that it altered the whole tone of one's
mind, and therefore that, when seeing a thing never seen by Lyell, one yet
saw it partially through his eyes--it would have been in some respects
better if I had done this less: but again excuse my long, and perhaps you
will think presumptuous, discussion. Enclosed is a note from Emma to Mrs.
Horner, to beg you, if you can, to give us the great pleasure of seeing you
here. We are necessarily dull here, and can offer no amusements; but the
weather is delightful, and if you could see how brightly the sun now shines
you would be tempted to come. Pray remember me most kindly to all your
family, and beg of them to accept our proposal, and give us the pleasure of
LETTER 481. TO C. LYELL.
Down, [September, 1844].
I was glad to get your note, and wanted to hear about your work. I have
been looking to see it advertised; it has been a long task. I had, before
your return from Scotland, determined to come up and see you; but as I had
nothing else to do in town, my courage has gradually eased off, more
especially as I have not been very well lately. We get so many invitations
here that we are grown quite dissipated, but my stomach has stood it so ill
that we are going to have a month's holidays, and go nowhere.
The subject which I was most anxious to talk over with you I have settled,
and having written sixty pages of my "S. American Geology," I am in pretty
good heart, and am determined to have very little theory and only short
descriptions. The two first chapters will, I think, be pretty good, on the
great gravel terraces and plains of Patagonia and Chili and Peru.
I am astonished and grieved over D'Orbigny's nonsense of sudden elevations.
(481/1. D'Orbigny's views are referred to by Lyell in chapter vii. of the
"Principles," Volume I. page 131. "This mud [i.e. the Pampean mud]
contains in it recent species of shells, some of them proper to brackish
water, and is believed by Mr. Darwin to be an estuary or delta deposit.
M.A. D'Orbigny, however, has advanced an hypothesis...that the agitation
and displacement of the waters of the ocean, caused by the elevation of the
Andes, gave rise to a deluge, of which this Pampean mud, which reaches
sometimes the height of 12,000 feet, is the result and monument.") I must
give you one of his cases: He finds an old beach 600 feet above sea. He
finds STILL ATTACHED to the rocks at 300 feet six species of truly littoral
shells. He finds at 20 to 30 feet above sea an immense accumulation of
chiefly littoral shells. He argues the whole 600 feet uplifted at one
blow, because the attached shells at 300 feet have not been displaced.
Therefore when the sea formed a beach at 600 feet the present littoral
shells were attached to rocks at 300 feet depth, and these same shells were
accumulating by thousands at 600 feet.
Hear this, oh Forbes. Is it not monstrous for a professed conchologist?
This is a fair specimen of his reasoning.
One of his arguments against the Pampas being a slow deposit, is that
mammifers are very seldom washed by rivers into the sea!
Because at 12,000 feet he finds the same kind of clay with that of the
Pampas he never doubts that it is contemporaneous with the Pampas
[debacle?] which accompanied the right royal salute of every volcano in the
Cordillera. What a pity these Frenchmen do not catch hold of a comet, and
return to the good old geological dramas of Burnett and Whiston. I shall
keep out of controversy, and just give my own facts. It is enough to
disgust one with Geology; though I have been much pleased with the frank,
decided, though courteous manner with which D'Orbigny disputes my
conclusions, given, unfortunately, without facts, and sometimes rashly, in
Enough of S. America. I wish you would ask Mr. Horner (for I forgot to do
so, and am unwilling to trouble him again) whether he thinks there is too
much detail (quite independent of the merits of the book) in my volcanic
volume; as to know this would be of some real use to me. You could tell me
when we meet after York, when I will come to town. I had intended being at
York, but my courage has failed. I should much like to hear your lecture,
but still more to read it, as I think reading is always better than
I am very glad you talk of a visit to us in the autumn if you can spare the
time. I shall be truly glad to see Mrs. Lyell and yourself here; but I
have scruples in asking any one--you know how dull we are here. Young
Hooker (481/2. Sir J.D. Hooker.) talks of coming; I wish he might meet
you,--he appears to me a most engaging young man.
I have been delighted with Prescott, of which I have read Volume I. at your
recommendation; I have just been a good deal interested with W. Taylor's
(of Norwich) "Life and Correspondence."
On your return from York I shall expect a great supply of Geological
LETTER 482. TO C. LYELL.
[October 3rd, 1846.]
I have been much interested with Ramsay, but have no particular suggestions
to offer (482/1. "On the Denudation of South Wales and the Adjacent
Counties of England." A.C. Ramsay, "Mem. Geol. Survey Great Britain,"
Volume I., London, 1846.); I agree with all your remarks made the other
day. My final impression is that the only argument against him is to tell
him to read and re-read the "Principles," and if not then convinced to send
him to Pluto. Not but what he has well read the "Principles!" and largely
profited thereby. I know not how carefully you have read this paper, but I
think you did not mention to me that he does (page 327) (482/2. Ramsay
refers the great outlines of the country to the action of the sea in
Tertiary times. In speaking of the denudation of the coast, he says:
"Taking UNLIMITED time into account, we can conceive that any extent of
land might be so destroyed...If to this be added an EXCEEDINGLY SLOW
DEPRESSION of the land and sea bottom, the wasting process would be
materially assisted by this depression" (loc. cit., page 327).) believe
that the main part of his great denudation was effected during a vast
(almost gratuitously assumed) slow Tertiary subsidence and subsequent
Tertiary oscillating slow elevation. So our high cliff argument is
inapplicable. He seems to think his great subsidence only FAVOURABLE for
great denudation. I believe from the general nature of the off-shore sea's
bottoms that it is almost necessary; do look at two pages--page 25 of my S.
American volume--on this subject. (482/3. "Geological Observations on S.
America," 1846, page 25. "When viewing the sea-worn cliffs of Patagonia,
in some parts between 800 and 900 feet in height, and formed of horizontal
Tertiary strata, which must once have extended far seaward...a difficulty
often occurred to me, namely, how the strata could possibly have been
removed by the action of the sea at a considerable depth beneath its
surface." The cliffs of St. Helena are referred to in illustration of the
same problem; speaking of these, Darwin adds: "Now, if we had any reason
to suppose that St. Helena had, during a long period, gone on slowly
subsiding, every difficulty would be removed...I am much inclined to
suspect that we shall hereafter find in all such cases that the land with
the adjoining bed of the sea has in truth subsided..." (loc. cit., pages
The foundation of his views, viz., of one great sudden upheaval, strikes me
as threefold. First, to account for the great dislocations. This strikes
me as the odder, as he admits that a little northwards there were many and
some violent dislocations at many periods during the accumulation of the
Palaeozoic series. If you argue against him, allude to the cool assumption
that petty forces are conflicting: look at volcanoes; look at recurrent
similar earthquakes at same spots; look at repeatedly injected intrusive
masses. In my paper on Volcanic Phenomena in the "Geol. Transactions."
(482/4. "On the Connection of certain Volcanic Phenomena, and on the
Formation of Mountain-chains and the Effects of Continental Elevations."
"Geol. Soc. Proc." Volume II., pages 654-60, 1838; "Trans. Geol. Soc."
Volume V., pages 601-32, 1842. [Read March 7th, 1838.]) I have argued
(and Lonsdale thought well of the argument, in favour, as he remarked, of
your original doctrine) that if Hopkins' views are correct, viz., that
mountain chains are subordinate consequences to changes of level in mass,
then, as we have evidence of such horizontal movements in mass having been
slow, the foundation of mountain chains (differing from volcanoes only in
matter being injected instead of ejected) must have been slow.
Secondly, Ramsay has been influenced, I think, by his Alpine insects; but
he is wrong in thinking that there is any necessary connection of tropics
and large insects--videlicet--Galapagos Arch., under the equator. Small
insects swarm in all parts of tropics, though accompanied generally with
Thirdly, he appears influenced by the absence of newer deposits on the old
area, blinded by the supposed necessity of sediment accumulating somewhere
near (as no doubt is true) and being PRESERVED--an example, as I think, of
the common error which I wrote to you about. The preservation of
sedimentary deposits being, as I do not doubt, the exception when they are
accumulated during periods of elevation or of stationary level, and
therefore the preservation of newer deposits would not be probable,
according to your view that Ramsay's great Palaeozoic masses were denuded,
whilst slowly rising. Do pray look at end of Chapter II., at what little I
have said on this subject in my S. American volume. (482/5. The second
chapter of the "Geological Observations" concludes with a Summary on the
Recent Elevations of the West Coast of South America, (page 53).)
I do not think you can safely argue that the whole surface was probably
denuded at same time to the level of the lateral patches of Magnesian
The latter part of the paper strikes me as good, but obvious.
I shall send him my S. American volume for it is curious on how many
similar points we enter, and I modestly hope it may be a half-oz. weight
towards his conversion to better views. If he would but reject his great
sudden elevations, how sound and good he would be. I doubt whether this
letter will be worth the reading.
LETTER 483. TO C. LYELL.
Down [September 4th, 1849].
It was very good of you to write me so long a letter, which has interested
me much. I should have answered it sooner, but I have not been very well
for the few last days. Your letter has also flattered me much in many
points. I am very glad you have been thinking over the relation of
subsidence and the accumulation of deposits; it has to me removed many
great difficulties; please to observe that I have carefully abstained from
saying that sediment is not deposited during periods of elevation, but only
that it is not accumulated to sufficient thickness to withstand subsequent
beach action; on both coasts of S. America the amount of sediment
deposited, worn away, and redeposited, oftentimes must have been enormous,
but still there have been no wide formations produced: just read my
discussion (page 135 of my S. American book (483/1. See Letter 556, note.
The discussion referred to ("Geological Observations on South America,"
1846) deals with the causes of the absence of recent conchiferous deposits
on the coasts of South America.)) again with this in your mind. I never
thought of your difficulty (i.e. in relation to this discussion) of where
was the land whence the three miles of S. Wales strata were derived!
(483/2. In his classical paper "On the Denudation of South Wales and the
Adjacent Counties of England" ("Mem. Geol. Survey," Volume I., page 297,
1846), Ramsay estimates the thickness of certain Palaeozoic formations in
South Wales, and calculates the cubic contents of the strata in the area
they now occupy together with the amount removed by denudation; and he goes
on to say that it is evident that the quantity of matter employed to form
these strata was many times greater than the entire amount of solid land
they now represent above the waves. "To form, therefore, so great a
thickness, a mass of matter of nearly equal cubic contents must have been
worn by the waves and the outpourings of rivers from neighbouring lands, of
which perhaps no original trace now remains" (page 334.)) Do you not think
that it may be explained by a form of elevation which I have always
suspected to have been very common (and, indeed, had once intended getting
all facts together), viz. thus?--
(Figure 1. A line drawing of ocean bottom subsiding beside mountains and
The frequency of a DEEP ocean close to a rising continent bordered with
mountains, seems to indicate these opposite movements of rising and sinking
CLOSE TOGETHER; this would easily explain the S. Wales and Eocene cases. I
will only add that I should think there would be a little more sediment
produced during subsidence than during elevation, from the resulting
outline of coast, after long period of rise. There are many points in my
volume which I should like to have discussed with you, but I will not
plague you: I should like to hear whether you think there is anything in
my conjecture on Craters of Elevation (483/3. In the "Geological
Observations on Volcanic Islands," 1844, pages 93-6, Darwin speaks of St.
Helena, St. Jago and Mauritius as being bounded by a ring of basaltic
mountains which he regards as "Craters of Elevation." While unable to
accept the theory of Elie de Beaumont and attribute their formation to a
dome-shaped elevation and consequent arching of the strata, he recognises a
"very great difficulty in admitting that these basaltic mountains are
merely the basal fragments of great volcanoes, of which the summits have
been either blown off, or, more probably, swallowed by subsidence." An
explanation of the origin and structure of these volcanic islands is
suggested which would keep them in the class of "Craters of Elevation," but
which assumes a slow elevation, during which the central hollow or platform
having been formed "not by the arching of the surface, but simply by that
part having been upraised to a less height."); I cannot possibly believe
that Saint Jago or Mauritius are the basal fragments of ordinary volcanoes;
I would sooner even admit E. de Beaumont's views than that--much as I would
sooner in my own mind in all cases follow you. Just look at page 232 in my
"S. America" for a trifling point, which, however, I remember to this day
relieved my mind of a considerable difficulty. (483/4. This probably
refers to a paragraph (page 232) "On the Eruptive Sources of the
Porphyritic Claystone and Greenstone Lavas." The opinion is put forward
that "the difficulty of tracing the streams of porphyries to their ancient
and doubtless numerous eruptive sources, may be partly explained by the
very general disturbance which the Cordillera in most parts has suffered";
but, Darwin adds, "a more specific cause may be that 'the original points
of eruption tend to become the points of injection'...On this view of there
being a tendency in the old points of eruption to become the points of
subsequent injection and disturbance, and consequently of denudation, it
ceases to be surprising that the streams of lava in the porphyritic
claystone conglomerate formation, and in other analogous cases, should most
rarely be traceable to their actual sources." The latter part of this
letter is published in "Life and Letters," I., pages 377, 378.) I remember
being struck with your discussion on the Mississippi beds in relation to
Pampas, but I should wish to read them over again; I have, however, re-lent
your work to Mrs. Rich, who, like all whom I have met, has been much
interested by it. I will stop about my own Geology. But I see I must
mention that Scrope did suggest (and I have alluded to him, page 118
(483/5. "Geological Observations," Edition II., 1876. Chapter VI. opens
with a discussion "On the Separation of the Constituent Minerals of Lava,
according to their Specific Gravities." Mr. Darwin calls attention to the
fact that Mr. P. Scrope had speculated on the subject of the separation of
the trachytic and basaltic series of lavas (page 113).), but without
distinct reference and I fear not sufficiently, though I utterly forgot
what he wrote) the separation of basalt and trachyte; but he does not
appear to have thought about the crystals, which I believe to be the
keystone of the phenomenon. I cannot but think this separation of the
molten elements has played a great part in the metamorphic rocks: how else
could the basaltic dykes have come in the great granitic districts such as
those of Brazil? What a wonderful book for labour is d'Archiac!...(483/6.
Possibly this refers to d'Archiac's "Histoire des Progres de la Geologie,"
LETTER 484. TO LADY LYELL.
Down, Wednesday night [1849?].
I am going to beg a very very great favour of you: it is to translate one
page (and the title) of either Danish or Swedish or some such language. I
know not to whom else to apply, and I am quite dreadfully interested about
the barnacles therein described. Does Lyell know Loven, or his address and
title? for I must write to him. If Lyell knows him I would use his name as
introduction; Loven I know by name as a first-rate naturalist.
Accidentally I forgot to give you the "Footsteps," which I now return,
having ordered a copy for myself.
I sincerely hope the "Craters of Denudation" prosper; I pin my faith to
this view. (484/1. "On Craters of Denudation, with Observations on the
Structure and Growth of Volcanic Cones." "Proc. Geol. Soc." Volume VI.,
1850, pages 207-34. In a letter to Bunbury (January 17th, 1850) Lyell
wrote:..."Darwin adopts my views as to Mauritius, St. Jago, and so-called
elevation craters, which he has examined, and was puzzled with."--"Life of
Sir Charles Lyell," Volume II., page 158.)
Please tell Sir C. Lyell that outside the crater-like mountains at St.
Jago, even throughout a distance of two or three miles, there has been much
denudation of the older volcanic rocks contemporaneous with those of the
ring of mountains. (484/2. The island of St. Jago, one of the Cape de
Verde group, is fully described in the "Volcanic Islands," Chapter 1.)
I hope that you will not find the page troublesome, and that you will
forgive me asking you.
LETTER 485. TO C. LYELL.
[November 6th, 1849].
I have been deeply interested in your letter, and so far, at least, worthy
of the time it must have cost you to write it. I have not much to say. I
look at the whole question as settled. Santorin is splendid! it is
conclusive! it is perfect! (485/1. "The Gulf of Santorin, in the Grecian
Archipelago, has been for two thousand years a scene of active volcanic
operations. The largest of the three outer islands of the groups (to which
the general name of Santorin is given) is called Thera (or sometimes
Santorin), and forms more than two-thirds of the circuit of the Gulf"
("Principles of Geology," Volume II., Edition X., London, 1868, page 65).
Lyell attributed "the moderate slope of the beds in Thera...to their having
originally descended the inclined flanks of a large volcanic cone..."; he
refuted the theory of "Elevation Craters" by Leopold von Buch, which
explained the slope of the rocks in a volcanic mountain by assuming that
the inclined beds had been originally horizontal and subsequently tilted by
an explosion.) You have read Dufrenoy in a hurry, I think, and added to
the difficulty--it is the whole hill or "colline" which is composed of tuff
with cross-stratification; the central boss or "monticule" is simply
trachyte. Now, I have described one tuff crater at Galapagos (page 108)
(485/2. The pages refer to Darwin's "Geological Observations on the
Volcanic Islands, etc." 1844.) which has broken through a great solid sheet
of basalt: why should not an irregular mass of trachyte have been left in
the middle after the explosion and emission of mud which produced the
overlying tuff? Or, again, I see no difficulty in a mass of trachyte being
exposed by subsequent dislocations and bared or cleaned by rain. At
Ascension (page 40), subsequent to the last great aeriform explosion, which
has covered the country with fragments, there have been dislocations and a
large circular subsidence...Do not quote Banks' case (485/3. This refers
to Banks' Cove: see "Volcanic Islands," page 107.) (for there has been
some denudation there), but the "elliptic one" (page 105), which is 1,500
yards (three-quarters of a nautical mile) in internal diameter...and is the
very one the inclination of whose mud stream on tuff strata I measured
(before I had ever heard the name Dufrenoy) and found varying from 25 to 30
deg. Albemarle Island, instead of being a crater of elevation, as Von Buch
foolishly guessed, is formed of four great subaerial basaltic volcanoes
(page 103), of one of which you might like to know the external diameter of
the summit or crater was above three nautical miles. There are no "craters
of denudation" at Galapagos. (485/4. See Lyell "On Craters of Denudation,
with Observations on the Structure and Growth of Volcanic Cones," "Quart.
Journ. Geol. Soc." Volume VI., 1850, page 207.)
I hope you will allude to Mauritius. I think this is the instance on the
largest scale of any known, though imperfectly known.
If I were you I would give up consistency (or, at most, only allude in note
to your old edition) and bring out the Craters of Denudation as a new view,
which it essentially is. You cannot, I think, give it prominence as a
novelty and yet keep to consistency and passages in old editions. I should
grudge this new view being smothered in your address, and should like to
see a separate paper. The one great channel to Santorin and Palma, etc.,
etc., is just like the one main channel being kept open in atolls and
encircling barrier reefs, and on the same principle of water being driven
in through several shallow breaches.
I of course utterly reprobate my wild notion of circular elevation; it is a
satisfaction to me to think that I perceived there was a screw loose in the
old view, and, so far, I think I was of some service to you.
Depend on it, you have for ever smashed, crushed, and abolished craters of
elevation. There must be craters of engulfment, and of explosion (mere
modifications of craters of eruption), but craters of denudation are the
ones which have given rise to all the discussions.
Pray give my best thanks to Lady Lyell for her translation, which was as
clear as daylight to me, including "leglessness."
LETTER 486. TO C. LYELL.
Down [November 20th, 1849].
I remembered the passage in E. de B. [Elie de Beaumont] and have now re-
read it. I have always and do still entirely disbelieve it; in such a
wonderful case he ought to have hammered every inch of rock up to actual
junction; he describes no details of junction, and if I were in your place
I would absolutely dispute the fact of junction (or articulation as he
oddly calls it) on such evidence. I go farther than you; I do not believe
in the world there is or has been a junction between a dike and stream of
lava of exact shape of either (1) or (2) Figure 2].
(Figures 2, 3 and 4.)
If dike gave immediate origin to volcanic vent we should have craters of
[an] elliptic shape [Figure 3]. I believe that when the molten rock in a
dike comes near to the surface, some one two or three points will always
certainly chance to afford an easier passage upward to the actual surface
than along the whole line, and therefore that the dike will be connected
(if the whole were bared and dissected) with the vent by a column or cone
(see my elegant drawing) of lava [Figure 4]. I do not doubt that the dikes
are thus indirectly connected with eruptive vents. E. de B. seems to have
observed many of his T; now without he supposes the whole line of fissure
or dike to have poured out lava (which implies, as above remarked, craters
of an elliptic or almost linear shape) on both sides, how extraordinarily
improbable it is, that there should have been in a single line of section
so many intersections of points eruption; he must, I think, make his
orifices of eruption almost linear or, if not so, astonishingly numerous.
One must refer to what one has seen oneself: do pray, when you go home,
look at the section of a minute cone of eruption at the Galapagos, page 109
(486/1. "Geological Observations on Volcanic Islands." London, 1890, page
238.), which is the most perfect natural dissection of a crater which I
have ever heard of, and the drawing of which you may, I assure you, trust;
here the arching over of the streams as they were poured out over the lip
of the crater was evident, and are now thus seen united to the central
irregular column. Again, at St. Jago I saw some horizontal sections of the
bases of small craters, and the sources or feeders were circular. I really
cannot entertain a doubt that E. de B. is grossly wrong, and that you are
right in your view; but without most distinct evidence I will never admit
that a dike joins on rectangularly to a stream of lava. Your argument
about the perpendicularity of the dike strikes me as good.
The map of Etna, which I have been just looking at, looks like a sudden
falling in, does it not? I am not much surprised at the linear vent in
Santorin (this linear tendency ought to be difficult to a circular-crater-
of-elevation-believer), I think Abich (486/2. "Geologische Beobachtungen
uber die vulkanischen Erscheinungen und Bildungen in Unter- und Mittel-
Italien." Braunschweig, 1841.) describes having seen the same actual thing
forming within the crater of Vesuvius. In such cases what outline do you
give to the upper surface of the lava in the dike connecting them? Surely
it would be very irregular and would send up irregular cones or columns as
in my above splendid drawing.
At the Royal on Friday, after more doubt and misgiving than I almost ever
felt, I voted to recommend Forbes for Royal Medal, and that view was
carried, Sedgwick taking the lead.
I am glad to hear that all your party are pretty well. I know from
experience what you must have gone through. From old age with suffering
death must be to all a happy release. (486/3. This seems to refer to the
death of Sir Charles Lyell's father, which occurred on November 8th, 1849.)
I saw Dan Sharpe the other day, and he told me he had been working at the
mica schist (i.e. not gneiss) in Scotland, and that he was quite convinced
my view was right. You are wrong and a heretic on this point, I know well.
LETTER 487. TO C.H.L. WOODD.
Down, March 4th .
(487/1. The paper was sent in MS., and seems not to have been published.
Mr. Woodd was connected by marriage with Mr. Darwin's cousin, the late Rev.
W. Darwin Fox. It was perhaps in consequence of this that Mr. Darwin
proposed Mr. Woodd for the Geological Society.)
I have read over your paper with attention; but first let me thank you for
your very kind expressions towards myself. I really feel hardly competent
to discuss the questions raised by your paper; I feel the want of
mathematical mechanics. All such problems strike me as awfully
complicated; we do not even know what effect great pressure has on
retarding liquefaction by heat, nor, I apprehend, on expansion. The chief
objection which strikes me is a doubt whether a mass of strata, when
heated, and therefore in some slight degree at least softened, would bow
outwards like a bar of metal. Consider of how many subordinate layers each
great mass would be composed, and the mineralogical changes in any length
of any one stratum: I should have thought that the strata would in every
case have crumpled up, and we know how commonly in metamorphic strata,
which have undergone heat, the subordinate layers are wavy and sinuous,
which has always been attributed to their expansion whilst heated.
Before rocks are dried and quarried, manifold facts show how extremely
flexible they are even when not at all heated. Without the bowing out and
subsequent filling in of the roof of the cavity, if I understand you, there
would be no subsidence. Of course the crumpling up of the strata would
thicken them, and I see with you that this might compress the underlying
fluidified rock, which in its turn might escape by a volcano or raise a
weaker part of the earth's crust; but I am too ignorant to have any opinion
whether force would be easily propagated through a viscid mass like molten
rock; or whether such viscid mass would not act in some degree like sand
and refuse to transmit pressure, as in the old experiment of trying to
burst a piece of paper tied over the end of a tube with a stick, an inch or
two of sand being only interposed. I have always myself felt the greatest
difficulty in believing in waves of heat coming first to this and then to
that quarter of the world: I suspect that heat plays quite a subordinate
part in the upward and downward movements of the earth's crust; though of
course it must swell the strata where first affected. I can understand Sir
J. Herschel's manner of bringing heat to unheated strata--namely, by
covering them up by a mile or so of new strata, and then the heat would
travel into the lower ones. But who can tell what effect this mile or two
of new sedimentary strata would have from mere gravity on the level of the
supporting surface? Of course such considerations do not render less true
that the expansion of the strata by heat would have some effect on the
level of the surface; but they show us how awfully complicated the
phenomenon is. All young geologists have a great turn for speculation; I
have burned my fingers pretty sharply in that way, and am now perhaps
become over-cautious; and feel inclined to cavil at speculation when the
direct and immediate effect of a cause in question cannot be shown. How
neatly you draw your diagrams; I wish you would turn your attention to real
sections of the earth's crust, and then speculate to your heart's content
on them; I can have no doubt that speculative men, with a curb on, make far
the best observers. I sincerely wish I could have made any remarks of more
interest to you, and more directly bearing on your paper; but the subject
strikes me as too difficult and complicated. With every good wish that you
may go on with your geological studies, speculations, and especially
LETTER 488. TO C. LYELL.
Down, March 24th .
I have often puzzled over Dana's case, in itself and in relation to the
trains of S. American volcanoes of different heights in action at the same
time (page 605, Volume V. "Geological Transactions." (488/1. "On the
Connection of certain Volcanic Phenomena in South America, and on the
Formation of Mountain Chains and Volcanoes, as the Effect of the same Power
by which Continents are Elevated" ("Trans. Geol. Soc." Volume V., page 601,
1840). On page 605 Darwin records instances of the simultaneous activity
after an earthquake of several volcanoes in the Cordillera.)) I can throw
no light on the subject. I presume you remember that Hopkins (488/2. See
"Report on the Geological Theories of Elevation and Earthquakes," by W.
Hopkins, "Brit. Assoc. Rep." 1847, page 34.) in some one (I forget which)
of his papers discusses such cases, and urgently wishes the height of the
fluid lava was known in adjoining volcanoes when in contemporaneous action;
he argues vehemently against (as far as I remember) volcanoes in action of
different heights being connected with one common source of liquefied rock.
If lava was as fluid as water, the case would indeed be hopeless; and I
fancy we should be led to look at the deep-seated rock as solid though
intensely hot, and becoming fluid as soon as a crack lessened the tension
of the super-incumbent strata. But don't you think that viscid lava might
be very slow in communicating its pressure equally in all directions? I
remember thinking strongly that Dana's case within the one crater of
Kilauea proved too much; it really seems monstrous to suppose that the lava
within the same crater is not connected at no very great depth.
When one reflects on (and still better sees) the enormous masses of lava
apparently shot miles high up, like cannon-balls, the force seems out of
all proportion to the mere gravity of the liquefied lava; I should think
that a channel a little straightly or more open would determine the line of
explosion, like the mouth of a cannon compared to the touch-hole. If a
high-pressure boiler was cracked across, no one would think for a moment
that the quantity of water and steam expelled at different points depended
on the less or greater height of the water within the boiler above these
points, but on the size of the crack at these points; and steam and water
might be driven out both at top and bottom. May not a volcano be likened
to a protruding and cracked portion on a vast natural high-pressure boiler,
formed by the surrounding area of country? In fact, I think my simile
would be truer if the difference consisted only in the cracked case of the
boiler being much thicker in some parts than in others, and therefore
having to expel a greater thickness or depth of water in the thicker cracks
or parts--a difference of course absolutely as nothing.
I have seen an old boiler in action, with steam and drops of water spurting
out of some of the rivet-holes. No one would think whether the rivet-holes
passed through a greater or less thickness of iron, or were connected with
the water higher or lower within the boiler, so small would the gravity be
compared with the force of the steam. If the boiler had been not heated,
then of course there would be a great difference whether the rivet-holes
entered the water high or low, so that there was greater or less pressure
of gravity. How to close my volcanic rivet-holes I don't know.
I do not know whether you will understand what I am driving at, and it will
not signify much whether you do or not. I remember in old days (I may
mention the subject as we are on it) often wishing I could get you to look
at continental elevations as THE phenomenon, and volcanic outbursts and
tilting up of mountain chains as connected, but quite secondary, phenomena.
I became deeply impressed with the truth of this view in S. America, and I
do not think you hold it, or if so make it clear: the same explanation,
whatever it may be, which will account for the whole coast of Chili rising,
will and must apply to the volcanic action of the Cordillera, though
modified no doubt by the liquefied rock coming to the surface and reaching
water, and so [being] rendered explosive. To me it appears that this ought
to be borne in mind in your present subject of discussion. I have written
at too great length; and have amused myself if I have done you no good--so
LETTER 489. TO C. LYELL.
Down, July 5th .
I am very much obliged for your long letter, which has interested me much;
but before coming to the volcanic cosmogony I must say that I cannot gather
your verdict as judge and jury (and not as advocate) on the continental
extensions of late authors (489/1. See "Life and Letters," II., page 74;
Letter to Lyell, June 25th, 1856: also letters in the sections of the
present work devoted to Evolution and Geographical Distribution.), which I
must grapple with, and which as yet strikes me as quite unphilosophical,
inasmuch as such extensions must be applied to every oceanic island, if to
any one, as to Madeira; and this I cannot admit, seeing that the skeletons,
at least, of our continents are ancient, and seeing the geological nature
of the oceanic islands themselves. Do aid me with your judgment: if I
could honestly admit these great [extensions], they would do me good
With respect to active volcanic areas being rising areas, which looks so
pretty on the coral maps, I have formerly felt "uncomfortable" on exactly
the same grounds with you, viz. maritime position of volcanoes; and still
more from the immense thicknesses of Silurian, etc., volcanic strata, which
thicknesses at first impress the mind with the idea of subsidence. If this
could be proved, the theory would be smashed; but in deep oceans, though
the bottom were rising, great thicknesses of submarine lava might
accumulate. But I found, after writing Coral Book, cases in my notes of
submarine vesicular lava-streams in the upper masses of the Cordillera,
formed, as I believe, during subsidence, which staggered me greatly. With
respect to the maritime position of volcanoes, I have long been coming to
the conclusion that there must be some law causing areas of elevation
(consequently of land) and of subsidence to be parallel (as if balancing
each other) and closely approximate; I think this from the form of
continents with a deep ocean on one side, from coral map, and especially
from conversations with you on immense subsidences of the Carboniferous and
[other] periods, and yet with continued great supply of sediment. If this
be so, such areas, with opposite movements, would probably be separated by
sets of parallel cracks, and would be the seat of volcanoes and tilts, and
consequently volcanoes and mountains would be apt to be maritime; but why
volcanoes should cling to the rising edge of the cracks I cannot
conjecture. That areas with extinct volcanic archipelagoes may subside to
any extent I do not doubt.
Your view of the bottom of Atlantic long sinking with continued volcanic
outbursts and local elevations at Madeira, Canaries, etc., grates (but of
course I do not know how complex the phenomena are which are thus
explained) against my judgment; my general ideas strongly lead me to
believe in elevatory movements being widely extended. One ought, I think,
never to forget that when a volcano is in action we have distinct proof of
an action from within outwards. Nor should we forget, as I believe follows
from Hopkins (489/2. "Researches in Physical Geology," W. Hopkins, "Trans.
Phil. Soc. Cambridge," Volume VI., 1838. See also "Report on the
Geological Theories of Elevation and Earthquakes," W. Hopkins, "Brit.
Assoc. Rep." page 33, 1847 (Oxford meeting).), and as I have insisted in my
Earthquake paper, that volcanoes and mountain chains are mere accidents
resulting from the elevation of an area, and as mountain chains are
generally long, so should I view areas of elevation as generally large.
(489/3. "On the Connexion of certain Volcanic Phenomena in S. America, and
on the Formation of Mountain Chains and Volcanoes, as the Effect of the
same Power by which Continents are Elevated," "Trans. Geol. Soc." Volume
V., page 601, 1840. "Bearing in mind Mr. Hopkins' demonstration, if there
be considerable elevation there must be fissures, and, if fissures, almost
certainly unequal upheaval, or subsequent sinking down, the argument may be
finally thus put: mountain chains are the effects of continental
elevations; continental elevations and the eruptive force of volcanoes are
due to one great motive, now in progressive action..." (loc. cit., page
Your old original view that great oceans must be sinking areas, from there
being causes making land and yet there being little land, has always struck
me till lately as very good. But in some degree this starts from the
assumption that within periods of which we know anything there was either a
continent in such areas, or at least a sea-bottom of not extreme depth.
LETTER 490. TO C. LYELL.
King's Head Hotel, Sandown, Isle of Wight, July 18th .
I write merely to thank you for the abstract of the Etna paper. (490/1.
"On the Structure of Lavas which have Consolidated on Steep Slopes, with
Remarks on the Mode of Origin of Mount Etna and on the Theory of 'Craters
of Elevation,'" by C. Lyell, "Phil. Trans. R. Soc." Volume CXLVIII., page
703, 1859.) It seems to me a very grand contribution to our volcanic
knowledge. Certainly I never expected to see E. de B.'s [Elie de Beaumont]
theory of slopes so completely upset. He must have picked out favourable
cases for measurement. And such an array of facts he gives! You have
scotched, and will see die, I now think, the Crater of Elevation theory.
But what vitality there is in a plausible theory! (490/2. The rest of
this letter is published in "Life and Letters," II., page 129.)
LETTER 491. TO C. LYELL.
Down, November 25th .
I have endeavoured to think over your discussion, but not with much
success. You will have to lay down, I think, very clearly, what foundation
you argue from--four parts (which seems to me exceedingly moderate on your
part) of Europe being now at rest, with one part undergoing movement. How
it is, that from this you can argue that the one part which is now moving
will have rested since the commencement of the Glacial period in the
proportion of four to one, I do not pretend to see with any clearness; but
does not your argument rest on the assumption that within a given period,
say two or three million years, the whole of Europe necessarily has to
undergo movement? This may be probable or not so, but it seems to me that
you must explain the foundation of your argument from space to time, which
at first, to me was very far from obvious. I can, of course, see that if
you can make out your argument satisfactorily to yourself and others it
would be most valuable. I can imagine some one saying that it is not fair
to argue that the great plains of Europe and the mountainous districts of
Scotland and Wales have been at all subjected to the same laws of movement.
Looking to the whole world, it has been my opinion, from the very size of
the continents and oceans, and especially from the enormous ranges of so
many mountain-chains (resulting from cracks which follow from vast areas of
elevation, as Hopkins argues (491/1. See "Report on the Geological
Theories of Elevation and Earthquakes." by William Hopkins. "Brit. Assoc.
Rep." 1847, pages 33-92; also the Anniversary Address to the Geological
Society by W. Hopkins in 1852 ("Quart. Journ. Geol. Soc." Volume VIII.); in
this Address, pages lxviii et seq.) reference is made to the theory of
elevation which rests on the supposition "of the simultaneous action of an
upheaving force at every point of the area over which the phenomena of
elevation preserve a certain character of continuity...The elevated
mass...becomes stretched, and is ultimately torn and fissured in those
directions in which the tendency thus to tear is greatest...It is thus that
the complex phenomena of elevation become referable to a general and simple
mechanical cause...")) and from other reasons, it has been my opinion that,
as a general rule, very large portions of the world have been
simultaneously affected by elevation or subsidence. I can see that this
does not apply so strongly to broken Europe, any more than to the Malay
Archipelago. Yet, had I been asked, I should have said that probably
nearly the whole of Europe was subjected during the Glacial period to
periods of elevation and of subsidence. It does not seem to me so certain
that the kinds of partial movement which we now see going on show us the
kind of movement which Europe has been subjected to since the commencement
of the Glacial period. These notions are at least possible, and would they
not vitiate your argument? Do you not rest on the belief that, as
Scandinavia and some few other parts are now rising, and a few others
sinking, and the remainder at rest, so it has been since the commencement
of the Glacial period? With my notions I should require this to be made
pretty probable before I could put much confidence in your calculations.
You have probably thought this all over, but I give you the reflections
which come across me, supposing for the moment that you took the
proportions of space at rest and in movement as plainly applicable to time.
I have no doubt that you have sufficient evidence that, at the commencement
of the Glacial period, the land in Scotland, Wales, etc., stood as high or
higher than at present, but I forget the proofs.
Having burnt my own fingers so consumedly with the Wealden, I am fearful
for you, but I well know how infinitely more cautious, prudent, and
far-seeing you are than I am; but for heaven's sake take care of your
fingers; to burn them severely, as I have done, is very unpleasant.
Your 2 1/2 feet for a century of elevation seems a very handsome allowance.
can D. Forbes really show the great elevation of Chili? I am astounded at
it, and I took some pains on the point.
I do not pretend to say that you may not be right to judge of the past
movements of Europe by those now and recently going on, yet it somehow
grates against my judgment,--perhaps only against my prejudices.
As a change from elevation to subsidence implies some great subterranean or
cosmical change, one may surely calculate on long intervals of rest
between. Though, if the cause of the change be ever proved to be
astronomical, even this might be doubtful.
P.S.--I do not know whether I have made clear what I think probable, or at
least possible: viz., that the greater part of Europe has at times been
elevated in some degree equably; at other times it has all subsided
equably; and at other times might all have been stationary; and at other
times it has been subjected to various unequal movements, up and down, as
LETTER 492. TO C. LYELL.
Down, December 4th .
It certainly seems to me safer to rely solely on the slowness of
ascertained up-and-down movement. But you could argue length of probable
time before the movement became reversed, as in your letter. And might you
not add that over the whole world it would probably be admitted that a
larger area is NOW at rest than in movement? and this I think would be a
tolerably good reason for supposing long intervals of rest. You might even
adduce Europe, only guarding yourself by saying that possibly (I will not
say probably, though my prejudices would lead me to say so) Europe may at
times have gone up and down all together. I forget whether in a former
letter you made a strong point of upward movement being always interrupted
by long periods of rest. After writing to you, out of curiosity I glanced
at the early chapters in my "Geology of South America," and the areas of
elevation on the E. and W. coasts are so vast, and proofs of many
successive periods of rest so striking, that the evidence becomes to my
mind striking. With regard to the astronomical causes of change: in
ancient days in the "Beagle" when I reflected on the repeated great
oscillations of level on the very same area, and when I looked at the
symmetry of mountain chains over such vast spaces, I used to conclude that
the day would come when the slow change of form in the semi-fluid matter
beneath the crust would be found to be the cause of volcanic action, and of
all changes of level. And the late discussion in the "Athenaeum" (492/1.
"On the Change of Climate in Different Regions of the Earth." Letters from
Sir Henry James, Col. R.E., "Athenaeum," August 25th, 1860, page 256;
September 15th, page 355; September 29th, page 415; October 13th, page 483.
Also letter from J. Beete Jukes, Local Director of the Geological Survey of
Ireland, loc. cit., September 8th, page 322; October 6th, page 451.), by
Sir H. James (though his letter seemed to me mighty poor, and what Jukes
wrote good), reminded me of this notion. In case astronomical agencies
should ever be proved or rendered probable, I imagine, as in nutation or
precession, that an upward movement or protrusion of fluidified matter
below might be immediately followed by movement of an opposite nature.
This is all that I meant.
I have not read Jamieson, or yet got the number. (492/2. Possibly William
Jameson, "Journey from Quito to Cayambe," "Geog. Soc. Journ." Volume XXXI.,
page 184, 1861.) I was very much struck with Forbes' explanation of
n[itrate] of soda beds and the saliferous crust, which I saw and examined
at Iquique. (492/3. "On the Geology of Bolivia and Southern Peru," by D.
Forbes, "Quart. Journ. Geol. Soc." Volume XVII., page 7, 1861. Mr. Forbes
attributes the formation of the saline deposits to lagoons of salt water,
the communication of which with the sea has been cut off by the rising of
the land (loc. cit., page 13).) I often speculated on the greater rise
inland of the Cordilleras, and could never satisfy myself...
I have not read Stur, and am awfully behindhand in many things...(492/4.
The end of this letter is published as a footnote in "Life and Letters,"
II., page 352.)
(FIGURE 5. Map of part of South America and the Galapagos Archipelago.)
LETTER 493. TO C. LYELL.
Down, July 18th .
(493/1. The first part of this letter is published in "Life and Letters,"
III., page 71.)
(493/2. Tahiti (Society Islands) is coloured blue in the map showing the
distribution of the different kinds of reefs in "The Structure and
Distribution of Coral Reefs," Edition III., 1889, page 185. The blue
colour indicates the existence of barrier reefs and atolls which, on
Darwin's theory, point to subsidence.)
Tahiti is, I believe, rightly coloured, for the reefs are so far from the
land, and the ocean so deep, that there must have been subsidence, though
not very recently. I looked carefully, and there is no evidence of recent
elevation. I quite agree with you versus Herschel on Volcanic Islands.
(493/3. Sir John Herschel suggested that the accumulation on the sea-floor
of sediment, derived from the waste of the island, presses down the bed of
the ocean, the continent being on the other hand relieved of pressure;
"this brings about a state of strain in the crust which will crack in its
weakest spot, the heavy side going down, and the light side rising." In
discussing this view Lyell writes ("Principles," Volume II. Edition X.,
page 229), "This hypothesis appears to me of very partial application, for
active volcanoes, even such as are on the borders of continents, are rarely
situated where great deltas have been forming, whether in Pliocene or
post-Tertiary times. The number, also, of active volcanoes in oceanic
islands is very great, not only in the Pacific, but equally in the
Atlantic, where no load of coral matter...can cause a partial weighting and
pressing down of a supposed flexible crust.") Would not the Atlantic and
Antarctic volcanoes be the best examples for you, as there then can be no
coral mud to depress the bottom? In my "Volcanic Islands," page 126, I
just suggest that volcanoes may occur so frequently in the oceanic areas as
the surface would be most likely to crack when first being elevated. I
find one remark, page 128 (493/4. "Volcanic Islands," page 128: "The
islands, moreover, of some of the small volcanic groups, which thus border
continents, are placed in lines related to those along which the adjoining
shores of the continents trend" [see Figure 5].), which seems to me worth
consideration--viz. the parallelism of the lines of eruption in volcanic
archipelagoes with the coast lines of the nearest continent, for this seems
to indicate a mechanical rather than a chemical connection in both cases,
i.e. the lines of disturbance and cracking. In my "South American
Geology," page 185 (493/5. "Geological Observations on South America,"
London, 1846, page 185.), I allude to the remarkable absence at present of
active volcanoes on the east side of the Cordillera in relation to the
absence of the sea on this side. Yet I must own I have long felt a little
sceptical on the proximity of water being the exciting cause. The one
volcano in the interior of Asia is said, I think, to be near great lakes;
but if lakes are so important, why are there not many other volcanoes
within other continents? I have always felt rather inclined to look at the
position of volcanoes on the borders of continents, as resulting from coast
lines being the lines of separation between areas of elevation and
subsidence. But it is useless in me troubling you with my old
LETTER 494. TO A.R. WALLACE.
March 22nd .
(494/1. The following extract from a letter to Mr. Wallace refers to his
"Malay Archipelago," 1869.)
I have only one criticism of a general nature, and I am not sure that other
geologists would agree with me. You repeatedly speak as if the pouring out
of lava, etc., from volcanoes actually caused the subsidence of an
adjoining area. I quite agree that areas undergoing opposite movements are
somehow connected; but volcanic outbursts must, I think, be looked at as
mere accidents in the swelling up of a great dome or surface of plutonic
rocks, and there seems no more reason to conclude that such swelling or
elevation in mass is the cause of the subsidence, than that the subsidence
is the cause of the elevation, which latter view is indeed held by some
geologists. I have regretted to find so little about the habits of the
many animals which you have seen.
LETTER 495. TO C. LYELL.
Down, May 20th, 1869.
I have been much pleased to hear that you have been looking at my S.
American book (495/1. "Geological Observations on South America," London,
1846.), which I thought was as completely dead and gone as any pre-Cambrian
fossil. You are right in supposing that my memory about American geology
has grown very hazy. I remember, however, a paper on the Cordillera by D.
Forbes (495/2. "Geology of Bolivia and South Peru," by Forbes, "Quart.
Journ. Geol. Soc." Volume XVII., pages 7-62, 1861. Forbes admits that
there is "the fullest evidence of elevation of the Chile coast since the
arrival of the Spaniards. North of Arica, if we accept the evidence of M.
d'Orbigny and others, the proof of elevation is much more decided; and
consequently it may be possible that here, as is the case about Lima,
according to Darwin, the elevation may have taken place irregularly in
places..." (loc. cit., page 11).), with splendid sections, which I saw in
MS., but whether "referred" to me or lent to me I cannot remember. This
would be well worth your looking to, as I think he both supports and
criticises my views. In Ormerod's Index to the Journal (495/3.
"Classified Index to the Transactions, Proceedings and Quarterly Journal of
the Geological Society."), which I do not possess, you would, no doubt,
find a reference; but I think the sections would be worth borrowing from
Forbes. Domeyko (495/4. Reference is made by Forbes in his paper on
Bolivia and Peru to the work of Ignacio Domeyko on the geology of Chili.
Several papers by this author were published in the "Annales des Mines"
between 1840 and 1869, also in the "Comptes Rendus" of 1861, 1864, etc.)
has published in the "Comptes Rendus papers on Chili, but not, as far as I
can remember, on the structure of the mountains. Forbes, however, would
know. What you say about the plications being steepest in the central and
generally highest part of the range is conclusive to my mind that there has
been the chief axis of disturbance. The lateral thrusting has always
appeared to me fearfully perplexing. I remember formerly thinking that all
lateral flexures probably occurred deep beneath the surface, and have been
brought into view by an enormous superincumbent mass having been denuded.
If a large and deep box were filled with layers of damp paper or clay, and
a blunt wedge was slowly driven up from beneath, would not the layers above
it and on both sides become greatly convoluted, whilst those towards the
top would be only slightly arched? When I spoke of the Andes being
comparatively recent, I suppose that I referred to the absence of the older
formations. In looking to my volume, which I have not done for many years,
I came upon a passage (page 232) which would be worth your looking at, if
you have ever felt perplexed, as I often was, about the sources of volcanic
rocks in mountain chains. You have stirred up old memories, and at the
risk of being a bore I should like to call your attention to another point
which formerly perplexed me much--viz. the presence of basaltic dikes in
most great granitic areas. I cannot but think the explanation given at
page 123 of my "Volcanic Islands" is the true one. (495/5. On page 123 of
the "Geological Observations on the Volcanic Islands visited during the
Voyage of H.M.S. 'Beagle,'" 1844, Darwin quotes several instances of
greenstone and basaltic dikes intersecting granitic and allied metamorphic
rocks. He suggests that these dikes "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
oozing out, and being sucked into such fissures.")
LETTER 496. TO VICTOR CARUS.
Down, March 21st, 1876.
The very kind expressions in your letter have gratified me deeply.
I quite forget what I said about my geological works, but the papers
referred to in your letter are the right ones. I enclose a list with those
which are certainly not worth translating marked with a red line; but
whether those which are not thus marked with a red line are worth
translation you will have to decide. I think much more highly of my book
on "Volcanic Islands" since Mr. Judd, by far the best judge on the subject
in England, has, as I hear, learnt much from it.
I think the short paper on the "formation of mould" is worth translating,
though, if I have time and strength, I hope to write another and longer
paper on the subject.
I can assure you that the idea of any one translating my books better than
you never even momentarily crossed my mind. I am glad that you can give a
fairly good account of your health, or at least that it is not worse.
LETTER 497. TO T. MELLARD READE.
London, December 9th, 1880.
I am sorry to say that I do not return home till the middle of next week,
and as I order no pamphlets to be forwarded to me by post, I cannot return
the "Geolog. Mag." until my return home, nor could my servants pick it out
of the multitude which come by the post. (497/1. Article on "Oceanic
Islands," by T. Mellard Reade, "Geol. Mag." Volume VIII., page 75, 1881.)
As I remarked in a letter to a friend, with whom I was discussing Wallace's
last book (497/2. Wallace's "Island Life," 1880.), the subject to which
you refer seems to me a most perplexing one. The fact which I pointed out
many years ago, that all oceanic islands are volcanic (except St. Paul's,
and now this is viewed by some as the nucleus of an ancient volcano), seems
to me a strong argument that no continent ever occupied the great oceans.
(497/3. "During my investigations on coral reefs I had occasion to consult
the works of many voyagers, and I was invariably struck with the fact that,
with rare exceptions, the innumerable islands scattered through the
Pacific, Indian, and Atlantic Oceans were composed either of volcanic or of
modern coral rocks" ("Geological Observations on Volcanic Islands, etc."
Edition II., 1876, page 140).) Then there comes the statement from the
"Challenger" that all sediment is deposited within one or two hundred miles
from the shores, though I should have thought this rather doubtful with
respect to great rivers like the Amazons.
The chalk formerly seemed to me the best case of an ocean having extended
where a continent now stands; but it seems that some good judges deny that
the chalk is an oceanic deposit. On the whole, I lean to the side that the
continents have since Cambrian times occupied approximately their present
positions. But, as I have said, the question seems a difficult one, and
the more it is discussed the better.
LETTER 498. TO A. AGASSIZ.
Down, January 1st, 1881.
I must write a line or two to thank you much for having written to me so
long a letter on coral reefs at a time when you must have been so busy. Is
it not difficult to avoid believing that the wonderful elevation in the
West Indies must have been accompanied by much subsidence, notwithstanding
the state of Florida? (498/1. The Florida reefs cannot be explained by
subsidence. Alexander Agassiz, who has described these reefs in detail
("Three Cruises of the U.S. Coast and Geodetic Survey Steamer 'Blake,'" 2
volumes, London, 1888), shows that the southern extremity of the peninsula
"is of comparatively recent growth, consisting of concentric barrier-reefs,
which have been gradually converted into land by the accumulation of
intervening mud-flats" (see also Appendix II., page 287, to Darwin's "Coral
Reefs," by T.G. Bonney, Edition III., 1889.)) When reflecting in old days
on the configuration of our continents, the position of mountain chains,
and especially on the long-continued supply of sediment over the same
areas, I used to think (as probably have many other persons) that areas of
elevation and subsidence must as a general rule be separated by a single
great line of fissure, or rather of several closely adjoining lines of
fissure. I mention this because, when looking within more recent times at
charts with the depths of the sea marked by different tints, there seems to
be some connection between the profound depths of the ocean and the trends
of the nearest, though distant, continents; and I have often wished that
some one like yourself, to whom the subject was familiar, would speculate
P.S.--I do hope that you will re-urge your views about the reappearance of
old characters (498/2. See "Life and Letters," III., pages 245, 246.),
for, as far as I can judge, the most important views are often neglected
unless they are urged and re-urged.
I am greatly indebted to you for sending me very many most valuable works
published at your institution.
2.IX.II. ICE-ACTION, 1841-1882.
LETTER 499. TO C. LYELL.
Your extract has set me puzzling very much, and as I find I am better at
present for not going out, you must let me unload my mind on paper. I
thought everything so beautifully clear about glaciers, but now your case
and Agassiz's statement about the cavities in the rock formed by cascades
in the glaciers, shows me I don't understand their structure at all. I
wish out of pure curiosity I could make it out. (499/1. "Etudes sur les
Glaciers," by Louis Agassiz, 1840, contains a description of cascades (page
343), and "des cavites interieures" (page 348).)
If the glacier travelled on (and it certainly does travel on), and the
water kept cutting back over the edge of the ice, there would be a great
slit in front of the cascade; if the water did not cut back, the whole
hollow and cascade, as you say, must travel on; and do you suppose the next
season it falls down some crevice higher up? In any case, how in the name
of Heaven can it make a hollow in solid rock, which surely must be a work
of many years? I must point out another fact which Agassiz does not, as it
appears to me, leave very clear. He says all the blocks on the surface of
the glaciers are angular, and those in the moraines rounded, yet he says
the medial moraines whence the surface rocks come and are a part [of], are
only two lateral moraines united. Can he refer to terminal moraines alone
when he says fragments in moraines are rounded? What a capital book
Agassiz's is. In [reading] all the early part I gave up entirely the Jura
blocks, and was heartily ashamed of my appendix (499/2. "M. Agassiz has
lately written on the subject of the glaciers and boulders of the Alps. He
clearly proves, as it appears to me, that the presence of the boulders on
the Jura cannot be explained by any debacle, or by the power of ancient
glaciers driving before them moraines...M. Agassiz also denies that they
were transported by floating ice." ("Voyages of the 'Adventure' and
'Beagle,'" Volume III., 1839: "Journal and Remarks: Addenda," page 617.))
(and am so still of the manner in which I presumptuously speak of Agassiz),
but it seems by his own confession that ordinary glaciers could not have
transported the blocks there, and if an hypothesis is to be introduced the
sea is much simpler; floating ice seems to me to account for everything as
well as, and sometimes better than the solid glaciers. The hollows,
however, formed by the ice-cascades appear to me the strongest hostile
fact, though certainly, as you said, one sees hollow round cavities on
I am glad to observe that Agassiz does not pretend that direction of
scratches is hostile to floating ice. By the way, how do you and Buckland
account for the "tails" of diluvium in Scotland? (499/3. Mr. Darwin
speaks of the tails of diluvium in Scotland extending from the protected
side of a hill, of which the opposite side, facing the direction from which
the ice came, is marked by grooves and striae (loc. cit., pages 622, 623).)
I thought in my appendix this made out the strongest argument for rocks
having been scratched by floating ice.
Some facts about boulders in Chiloe will, I think, in a very small degree
elucidate some parts of Jura case. What a grand new feature all this ice
work is in Geology! How old Hutton would have stared! (499/4. Sir
Charles Lyell speaks of the Huttonian theory as being characterised by "the
exclusion of all causes not supposed to belong to the present order of
Nature" (Lyell's "Principles," Edition XII., volume I., page 76, 1875).
Sir Archibald Geikie has recently edited the third volume of Hutton's
"Theory of the Earth," printed by the Geological Society, 1899. See also
"The Founders of Geology," by Sir Archibald Geikie; London, 1897.)
I ought to be ashamed of myself for scribbling on so. Talking of shame, I
have sent a copy of my "Journal" (499/5. "Journal and Remarks," 1832-36.
See note 2, page 148.) with very humble note to Agassiz, as an apology for
the tone I used, though I say, I daresay he has never seen my appendix, or
would care at all about it.
I did not suppose my note about Glen Roy could have been of any use to
you--I merely scribbled what came uppermost. I made one great oversight,
as you would perceive. I forgot the Glacier theory: if a glacier most
gradually disappeared from mouth of Spean Valley [this] would account for
buttresses of shingle below lowest shelf. The difficulty I put about the
ice-barrier of the middle Glen Roy shelf keeping so long at exactly same
level does certainly appear to me insuperable. (499/5. For a description
of the shelves or parallel roads in Glen Roy see Darwin's "Observations on
the Parallel Roads of Glen Roy, etc." "Phil. Trans. R. Soc." 1839, page
39; also Letter 517 et seq.)
What a wonderful fact this breakdown of old Niagara is. How it disturbs
the calculations about lengths of time before the river would have reached
I hope Mrs. Lyell will read this to you, then I shall trust for forgiveness
for having scribbled so much. I should have sent back Agassiz sooner, but
my servant has been very unwell. Emma is going on pretty well.
My paper on South American boulders and "till," which latter deposit is
perfectly characterised in Tierra del Fuego, is progressing rapidly.
(499/6. "On the Distribution of the Erratic Boulders and on the
Contemporaneous Unstratified Deposits of South America," "Trans. Geol.
Soc." Volume VI., page 415, 1842.)
I much like the term post-Pliocene, and will use it in my present paper
P.S.--I should have thought that the most obvious objection to the marine-
beach theory for Glen Roy would be the limited extension of the shelves.
Though certainly this is not a valid one, after an intermediate one, only
half a mile in length, and nowhere else appearing, even in the valley of
Glen Roy itself, has been shown to exist.
LETTER 500. TO C. LYELL.
I had some talk with Murchison, who has been on a flying visit into Wales,
and he can see no traces of glaciers, but only of the trickling of water
and of the roots of the heath. It is enough to make an extraneous man
think Geology from beginning to end a work of imagination, and not founded
on observation. Lonsdale, I observe, pays Buckland and myself the
compliment of thinking Murchison not seeing as worth nothing; but I confess
I am astonished, so glaringly clear after two or three days did the
evidence appear to me. Have you seen last "New Edin. Phil. Journ.", it is
ice and glaciers almost from beginning to end. (500/1. "The Edinburgh New
Philosophical Journal," Volume XXXIII. (April-October), 1842, contains
papers by Sir G.S. Mackenzie, Prof. H.G. Brown, Jean de Charpentier,
Roderick Murchison, Louis Agassiz, all dealing with glaciers or ice; also
letters to the Editor relating to Prof. Forbes' account of his recent
observations on Glaciers, and a paper by Charles Darwin entitled "Notes on
the Effects produced by the Ancient Glaciers of Carnarvonshire, and on the
Boulders transported by Floating Ice.") Agassiz says he saw (and has laid
down) the two lowest terraces of Glen Roy in the valley of the Spean,
opposite mouth of Glen Roy itself, where no one else has seen them. (500/2.
"The Glacial Theory and its Recent Progress," by Louis Agassiz, loc. cit.,
page 216. Agassiz describes the parallel terraces on the flanks of Glen
Roy and Glen Spean (page 236), and expresses himself convinced "that the
Glacial theory alone satisfies all the exigencies of the phenomenon" of the
parallel roads.) I carefully examined that spot, owing to the sheep tracks
[being] nearly but not quite parallel to the terrace. So much, again, for
difference of observation. I do not pretend to say who is right.
LETTER 501. TO J.D. HOOKER.
Down, October 12th, 1849.
I was heartily glad to get your last letter; but on my life your thanks for
my very few and very dull letters quite scalded me. I have been very
indolent and selfish in not having oftener written to you and kept my ears
open for news which would have interested you; but I have not forgotten
you. Two days after receiving your letter, there was a short leading
notice about you in the "Gardeners' Chronicle" (501/1. The "Gardeners'
Chronicle," 1849, page 628.); in which it is said you have discovered a
noble crimson rose and thirty rhododendrons. I must heartily congratulate
you on these discoveries, which will interest the public; and I have no
doubt that you will have made plenty of most interesting botanical
observations. This last letter shall be put with all your others, which
are now safe together. I am very glad that you have got minute details
about the terraces in the valleys: your description sounds curiously like
the terraces in the Cordillera of Chili; these latter, however, are single
in each valley; but you will hereafter see a description of these terraces
in my "Geology of S. America." (501/2. "Geological Observations," pages
10 et passim.) At the end of your letter you speak about giving up
Geology, but you must not think of it; I am sure your observations will be
very interesting. Your account of the great dam in the Yangma valley is
most curious, and quite full; I find that I did not at all understand its
wonderful structure in your former letter. Your notion of glaciers pushing
detritus into deep fiords (and ice floating fragments on their channels),
is in many respects new to me; but I cannot help believing your dam is a
lateral moraine: I can hardly persuade myself that the remains of floating
ice action, at a period so immensely remote as when the Himalaya stood at a
low level in the sea, would now be distinguishable. (501/3. Hooker's
"Himalayan Journals," Volume II., page 121, 1854. In describing certain
deposits in the Lachoong valley, Hooker writes: "Glaciers might have
forced immense beds of gravel into positions that would dam up lakes
between the ice and the flanks of the valley" (page 121). In a footnote he
adds: "We are still very ignorant of many details of ice action, and
especially of the origin of many enormous deposits which are not true
moraines." Such deposits are referred to as occurring in the Yangma
valley.) Your not having found scored boulders and solid rocks is an
objection both to glaciers and floating ice; for it is certain that both
produce such. I believe no rocks escape scoring, polishing and
mammillation in the Alps, though some lose it easily when exposed. Are you
familiar with appearance of ice-action? If I understand rightly, you
object to the great dam having been produced by a glacier, owing to the
dryness of the lateral valley and general infrequency of glaciers in
Himalaya; but pray observe that we may fairly (from what we see in Europe)
assume that the climate was formerly colder in India, and when the land
stood at a lower height more snow might have fallen. Oddly enough, I am
now inclined to believe that I saw a gigantic moraine crossing a valley,
and formerly causing a lake above it in one of the great valleys (Valle del
Yeso) of the Cordillera: it is a mountain of detritus, which has puzzled
me. If you have any further opportunities, do look for scores on steep
faces of rock; and here and there remove turf or matted parts to have a
look. Again I beg, do not give up Geology:--I wish you had Agassiz's work
and plates on Glaciers. (501/4. "Etudes sur les Glaciers." L. Agassiz,
Neuchatel, 1840.) I am extremely sorry that the Rajah, ill luck to him,
has prevented your crossing to Thibet; but you seem to have seen most
interesting country: one is astonished to hear of Fuegian climate in
India. I heard from the Sabines that you were thinking of giving up
Borneo; I hope that this report may prove true.
LETTER 502. TO C. LYELL.
Down, May 8th .
The notion you refer to was published in the "Geological Journal" (502/1.
"on the Transportal of Erratic Boulders from a lower to a higher Level."
By C. Darwin.), Volume IV. (1848), page 315, with reference to all the
cases which I could collect of boulders apparently higher than the parent
The argument of probable proportion of rock dropped by sea ice compared to
land glaciers is new to me. I have often thought of the idea of the
viscosity and enormous momentum of great icebergs, and still think that the
notion I pointed out in appendix to Ramsay's paper is probable, and can
hardly help being applicable in some cases. (502/2. The paper by Ramsay
has no appendix; probably, therefore Mr. Darwin's notes were published
separately as a paper in the "Phil. Mag.") I wonder whether the "Phil.
Journal [Magazine?.]" would publish it, if I could get it from Ramsay or
the Geological Society. (502/3. "On the Power of Icebergs to make
rectilinear, uniformly-directed grooves across a Submarine Undulatory
Surface." By C. Darwin, "Phil. Mag." Volume X., page 96, 1855.) If you
chance to meet Ramsay will you ask him whether he has it? I think it would
perhaps be worth while just to call the N. American geologists' attention
to the idea; but it is not worth any trouble. I am tremendously busy with
all sorts of experiments. By the way, Hopkins at the Geological Society
seemed to admit some truth in the idea of scoring by (viscid) icebergs. If
the Geological Society takes so much [time] to judge of truth of notions,
as you were telling me in regard to Ramsay's Permian glaciers (502/4. "On
the Occurrence of angular, sub-angular, polished, and striated Fragments
and Boulders in the Permian Breccia of Shropshire, Worcestershire, etc.;
and on the Probable Existence of Glaciers and Icebergs in the Permian
Epoch." By A.C. Ramsay, "Quart. Journ. Geol. Soc." Volume XI., page 185,
1855.), it will be as injurious to progress as the French Institut.
LETTER 503. TO J.D. HOOKER.
Cliff Cottage, Bournemouth, [September] 21st .
I am especially obliged to you for sending me Haast's communications.
(503/1. "Quart. Journ. Geol. Soc." Volume XXI., pages 130, 133, 1865;
Volume XXIII., page 342, 1867.) They are very interesting and grand about
glacial and drift or marine glacial. I see he alludes to the whole
southern hemisphere. I wonder whether he has read the "Origin."
Considering your facts on the Alpine plants of New Zealand and remarks, I
am particularly glad to hear of the geological evidence of glacial action.
I presume he is sure to collect and send over the mountain rat of which he
speaks. I long to know what it is. A frog and rat together would, to my
mind, prove former connection of New Zealand to some continent; for I can
hardly suppose that the Polynesians introduced the rat as game, though so
esteemed in the Friendly Islands. Ramsay sent me his paper (503/2. "On
the Glacial Origin of certain Lakes in Switzerland, etc." "Quart. Journ.
Geol. Soc." Volume XVIII., page 185, 1862.) and asked my opinion on it. I
agree with you and think highly of it. I cannot doubt that it is to a
large extent true; my only doubt is, that in a much disturbed country, I
should have thought that some depressions, and consequently lakes, would
almost certainly have been left. I suggested a careful consideration of
mountainous tropical countries such as Brazil, peninsula of India, etc.; if
lakes are there, [they are] very rare. I should fully subscribe to
What presumption, as it seems to me, in the Council of Geological Society
that it hesitated to publish the paper.
We return home on the 30th. I have made up [my] mind, if I can keep up my
courage, to start on the Saturday for Cambridge, and stay the last few days
of the [British] Association there. I do so hope that you may be there
LETTER 504. TO J.D. HOOKER.
November 3rd .
When I wrote to you I had not read Ramsay. (504/1. "On the Erosion of
Valleys and Lakes: a Reply to Sir Roderick Murchison's Anniversary Address
to the Geographical Society." "Phil. Mag." Volume XXVIII., page 293, 1864)
How capitally it is written! It seems that there is nothing for style like
a man's dander being put up. I think I agree largely with you about
denudation--but the rocky-lake-basin theory is the part which interests me
at present. It seems impossible to know how much to attribute to ice,
running water, and sea. I did not suppose that Ramsay would deny that
mountains had been thrown up irregularly, and that the depressions would
become valleys. The grandest valleys I ever saw were at Tahiti, and here I
do not believe ice has done anything; anyhow there were no erratics. I
said in my S. American Geology (504/2. "Finally, the conclusion at which I
have arrived with respect to the relative powers of rain, and sea-water on
the land is, that the latter is by far the most efficient agent, and that
its chief tendency is to widen the valleys, whilst torrents and rivers tend
to deepen them and to remove the wreck of the sea's destroying action"
("Geol. Observations," pages 66, 67).) that rivers deepen and the sea
widens valleys, and I am inclined largely to stick to this, adding ice to
water. I am sorry to hear that Tyndall has grown dogmatic. H. Wedgwood
was saying the other day that T.'s writings and speaking gave him the idea
of intense conceit. I hope it is not so, for he is a grand man of science.
...I have had a prospectus and letter from Andrew Murray (504/3. See
Volume II., Letters 379, 384, etc.) asking me for suggestions. I think
this almost shows he is not fit for the subject, as he gives me no idea
what his book will be, excepting that the printed paper shows that all
animals and all plants of all groups are to be treated of. Do you know
anything of his knowledge?
In about a fortnight I shall have finished, except concluding chapter, my
book on "Variation under Domestication"; (504/4. Published in 1868.) but
then I have got to go over the whole again, and this will take me very many
months. I am able to work about two hours daily.
LETTER 505. TO J.D. HOOKER.
Down [July, 1865].
I was glad to read your article on Glaciers, etc., in Yorkshire. You seem
to have been struck with what most deeply impressed me at Glen Roy (wrong
as I was on the whole subject)--viz. the marvellous manner in which every
detail of surface of land had been preserved for an enormous period. This
makes me a little sceptical whether Ramsay, Jukes, etc., are not a little
overdoing sub-aerial denudation.
In the same "Reader" (505/1. Sir J.D. Hooker wrote to Darwin, July 13th,
1865, from High Force Inn, Middleton, Teesdale: "I am studying the
moraines all day long with as much enthusiasm as I am capable of after
lying in bed till nine, eating heavy breakfasts, and looking forward to
dinner as the summum bonum of existence." The result of his work, under
the title "Moraines of the Tees Valley," appeared in the "Reader" (July
15th, 1865, page 71), of which Huxley was one of the managers or
committee-men, and Norman Lockyer was scientific editor ("Life and Letters
of T.H. Huxley," I., page 211). Hooker describes the moraines and other
evidence of glacial action in the upper part of the Tees valley, and speaks
of the effect of glaciers in determining the present physical features of
the country.) there was a striking article on English and Foreign Men of
Science (505/2. "British and Foreign Science," "The Reader," loc. cit.,
page 61. The writer of the article asserts the inferiority of English
scientific workers.), and I think unjust to England except in pure
Physiology; in biology Owen and R. Brown ought to save us, and in Geology
we are most rich.
It is curious how we are reading the same books. We intend to read Lecky
and certainly to re-read Buckle--which latter I admired greatly before. I
am heartily glad you like Lubbock's book so much. It made me grieve his
taking to politics, and though I grieve that he has lost his election, yet
I suppose, now that he is once bitten, he will never give up politics, and
science is done for. Many men can make fair M.P.'s; and how few can work
in science like him!
I have been reading a pamphlet by Verlot on "Variation of Flowers," which
seems to me very good; but I doubt whether it would be worth your reading.
it was published originally in the "Journal d'Hort.," and so perhaps you
have seen it. It is a very good plan this republishing separately for sake
of foreigners buying, and I wish I had tried to get permission of Linn.
Soc. for my Climbing paper, but it is now too late.
Do not forget that you have my paper on hybridism, by Max Wichura. (505/3.
Wichura, M.E., "L'Hybridisation dans le regne vegetal etudiee sur les
Saules," "Arch. Sci. Phys. Nat." XXIII., page 129, 1865.)
I hope you are returned to your work, refreshed like a giant by your huge
breakfasts. How unlucky you are about contagious complaints with your
I keep very weak, and had much sickness yesterday, but am stronger this
Can you remember how we ever first met? (505/4. See "Life and Letters,"
II., page 19.) It was in Park Street; but what brought us together? I
have been re-reading a few old letters of yours, and my heart is very warm
LETTER 506. TO C. LYELL.
Down, March 8th .
(506/1. In a letter from Sir Joseph Hooker to Mr. Darwin on February 21st,
1866, the following passage occurs: "I wish I could explain to you my
crude notions as to the Glacial period and your position towards it. I
suppose I hold this doctrine: that there was a Glacial period, but that it
was not one of universal cold, because I think that the existing
distribution of glaciers is sufficiently demonstrative of the proposition
that by comparatively slight redispositions of sea and land, and perhaps
axis of globe, you may account for all the leading palaeontological
phenomena." This letter was sent by Mr. Darwin to Sir Charles Lyell, and
the latter, writing on March 1st, 1866, expresses his belief that "the
whole globe must at times have been superficially cooler. Still," he adds,
"during extreme excentricity the sun would make great efforts to compensate
in perihelion for the chill of a long winter in aphelion in one hemisphere,
and a cool summer in the other. I think you will turn out to be right in
regard to meridional lines of mountain-chains by which the migrations
across the equator took place while there was contemporaneous tropical heat
of certain lowlands, where plants requiring heat and moisture were saved
from extinction by the heat of the earth's surface, which was stored up in
perihelion, being prevented from radiating off freely into space by a
blanket of aqueous vapour caused by the melting of ice and snow. But
though I am inclined to profit by Croll's maximum excentricity for the
glacial period, I consider it quite subordinate to geographical causes or
the relative position of land and sea and the abnormal excess of land in
polar regions." In another letter (March 5th, 1866) Lyell writes: "In the
beginning of Hooker's letter to you he speaks hypothetically of a change in
the earth's axis as having possibly co-operated with redistribution of land
and sea in causing the cold of the Glacial period. Now, when we consider
how extremely modern, zoologically and botanically, the Glacial period is
proved to be, I am shocked at any one introducing, with what I may call so
much levity, so organic a change as a deviation in the axis of the
planet...' (see Lyell's "Principles," 1875, Chapter XIII.; also a letter to
Sir Joseph Hooker printed in the "Life of Sir Charles Lyell," Volume II.,
Many thanks for your interesting letter. From the serene elevation of my
old age I look down with amazement at your youth, vigour, and indomitable
energy. With respect to Hooker and the axis of the earth, I suspect he is
too much overworked to consider now any subject properly. His mind is so
acute and critical that I always expect to hear a torrent of objections to
anything proposed; but he is so candid that he often comes round in a year
or two. I have never thought on the causes of the Glacial period, for I
feel that the subject is beyond me; but though I hope you will own that I
have generally been a good and docile pupil to you, yet I must confess that
I cannot believe in change of land and water, being more than a subsidiary
agent. (506/2. In Chapter XI. of the "Origin," Edition V., 1869, page
451, Darwin discusses Croll's theory, and is clearly inclined to trust in
Croll's conclusion that "whenever the northern hemisphere passes through a
cold period the temperature of the southern hemisphere is actually
raised..." In Edition VI., page 336, he expresses his faith even more
strongly. Mr. Darwin apparently sent his MS. on the climate question,
which was no doubt prepared for a new edition of the "Origin," to Sir
Charles. The arrival of the MS. is acknowledged in a letter from Lyell on
March 10th, 1866 ("Life of Sir Charles Lyell," II., page 408), in which the
writer says that he is "more than ever convinced that geographical
changes...are the principal and not the subsidiary causes.") I have come
to this conclusion from reflecting on the geographical distribution of the
inhabitants of the sea on the opposite sides of our continents and of the
inhabitants of the continents themselves.
LETTER 507. TO C. LYELL.
Down, September 8th .
Many thanks for the pamphlet, which was returned this morning. I was very
glad to read it, though chiefly as a psychological curiosity. I quite
follow you in thinking Agassiz glacier-mad. (507/1. Agassiz's pamphlet,
("Geology of the Amazons") is referred to by Lyell in a letter written to
Bunbury in September, 1866 ("Life of Sir Charles Lyell," II., page 409):
"Agassiz has written an interesting paper on the 'Geology of the Amazons,'
but, I regret to say, he has gone wild about glaciers, and has actually
announced his opinion that the whole of the great valley, down to its mouth
in latitude 0 deg., was filled by ice..." Agassiz published a paper,
"Observations Geologiques faites dans la Vallee de l'Amazone," in the
"Comptes Rendus," Volume LXIV., page 1269, 1867. See also a letter
addressed to M. Marcou, published in the "Bull. Soc. Geol. France," Volume
XXIV., page 109, 1866.) His evidence reduces itself to supposed moraines,
which would be difficult to trace in a forest-clad country; and with
respect to boulders, these are not said to be angular, and their source
cannot be known in a country so imperfectly explored. When I was at Rio, I
was continually astonished at the depth (sometimes 100 feet) to which the
granitic rocks were decomposed in situ, and this soft matter would easily
give rise to great alluvial accumulations; I well remember finding it
difficult to draw a line between the alluvial matter and the softened rock
in situ. What a splendid imagination Agassiz has, and how energetic he is!
What capital work he would have done, if he had sucked in your "Principles"
with his mother's milk. It is wonderful that he should have written such
wild nonsense about the valley of the Amazon; yet not so wonderful when one