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Darwin Correspondence Project

From J. D. Hooker   30 September 1849

Thibet frontier | Camp | Sikkim Himal1

Sept 30/49

Carissimo Darwin

Motive for the 2d. Edition of Darwin’s Geolog of S. America

Stratification is vexation, Foliation’s twice as bad; Where joints there be, They puzzle me; And Cleavage drives me mad.

Dear Darwin

I have been reading your Geology of S. Am. with immense profit & pleasure, & have to own myself duly & truly ashamed of not having done so before.— You are partly right & partly wrong in supposing that what I called stratification was your foliation I of course included the foliation in the stratification but in the Himal. both fol. & strat are so disturbed down to the individual leaves, that I never measure or judge except from the Strata by which I understand the individual masses if differing in relative amount of Quartz Mica or Feldspar, & which strata are further foliated or stratified throughout. To begin at the beginning I premise that Gneiss Mica Schist & Clay slate are our only rocks except the intruded. Of these the Gneiss is all prevalent, the M.S. not unfrequent & the Clayslate rare & confined to the base of the outer range & bottoms of a few valleys. Do what I will & go where I will I can never find the C.S. but below the M.S & the MS. below the Gneiss— Mc Lelland writes me that he finds the same in the Curruckpore range (S. of the Ganges) substituting I think Hornblende for Mica schist.2 What is most puzzling of all; the clay slate overlies the recent sandstone with coal & coal fossils at the foot of the hills.! except there be some complete fold or overturn of a Mt 8000 ft high. I do not of course say it is so, but Hodgson & myself spent weeks down there in futile endeavors to unravel the real or apparent anomaly. I hope Thomson is coming to meet me in a couple of months & we will have another overhaul.

Now for your question— the Strat. & foliation & Cleavage are throughout the Himal. parallel to & conformable to one another. I have no where found the foliation to be but to appearance a lesser stratification (in degree) & the cleavage is always along the Strat planes. On the other hand I never did look on foliation as a water action or a sure index of the deposition of the folia from water but being a sneering skeptic I kept my heresy to myself & was not going to break my head against the stony gizzards of Deans & Doctors.3 Not that I can any way explain foliation, even so partially as you do, but nobody once could make me believe that the convoluted individual folia of quartz mica & feldspar were due to pressure on such a paste as was soft enough to yield to the pressure & yet so consistent as that the elements should not intimately mix— The double action of chemical aggregation & pressure I have always thought might accomplish it. Again the eye like concretions of both Quartz & feldspar, from an inch to a foot in diam. abound throughout the Gneiss, the laminæ foliate round these ellipsees, concentrically, & regularly—folia of feldspar Quartz & mica— Now the only other way of explaining these lenses is a partial fusion during metamorphosis but these are either of Quartz & of Feldspar sometimes of both, a very different amount of heat is required for either, & the thin folia above & below of both minerals could not stand that. Now where the plutonic rocks erupt, at 17 & 19000 ft I find it utterly impossible to distinguish at once which is the erupted & ⁠⟨⁠which⁠⟩⁠ the so called sedimentary rock., for the latter by metamorphosis looses its foliated character, & most distinctly erupted veins assume it, the tendency being to assume it in wavy lines & of the mica to concrete in broken i.e. non continuous plates, enclosing continuous beds an inch or so thick of Q. & F. always like beads soldered (or my lenses) together. The black lines here represent the micah. diagram

Again if my eyes did not deceive me I passed two days ago an enormous mass of Gneiss, traversed with a vein 4 feet broad, which vein was distorted & contorted far more than the Gneiss itself. Unluckily this was only a huge block recently come down from the Mts. & I could not be positive which was the vein—but that one foliated rock enclosed another was as clear as in your sketch of the Rio rock.4 diagram

A long story again arises out of the formation chrystallization & I take it re chrystallization of the Garnets & their arrangement now in veins & now in the sed. rock,—equally dispersed through all the mineral constituents in one metamorphosed area,—confined to the Feldspar & Quartz in another— but there I am still further beyond my depth. Unfortunately it is extremely difficult to follow the Geology in its details of these Mts. In the first place the disturbance is too great, & in the next it is a most difficult country to explore.

I am not going to condescend to give you any more glacial action, I may just say that you could not be silent on the phemonomena I see here had you the remotest similarity to them in the Andes. I have been exploring two splendid live glaciers at 17 & 19000 ft & trace a perfect continuity of the moraine hills (500 & 1000 ft above the flanks & floors of the valleys) from 19000 down to 12000 ft.5

I now write from 9000 ft, & could you see the lovely clear cut perfectly level terraces along both flanks of this (Lachoong) valley, abutting on a precipitous Mt 18000 ft high rising in steps 1000 ft above the floor, you would not be so skeptical of a poor ignoramus even on water action. A fatter man with less to do will come & reduce it all to feet & degrees & you will then believe.

I have heaps & heaps of things to remark upon in your S. Am. Geolog. in which I assure you I have been deeply interested, it is a most capital book in matter & extremely well written. How you would have laughed could you have seen me perusing it with avidity up at 16000 ft where I camped for 20 days, & where the volume came to my hands. Lying in bed huddled up in blankets with the smallest possible tip of one finger exposed to turn the pages, the skin off both nose & cheeks & holding the book with my hand cased in the blanket so awkwardly that it ever & anon bumped on to my face & deranged my spectacles.— I still read in bed you see, & indeed the severity of the cold is such at these elevations, that even with a fire at the mouth of the tent you cannot work when the sun is down without always warming your fingers.

You say the late Dr Malcolmson6 —I think he is alive if there be not two such men. entre nous he is said to drink— Lord D.7 has appointed him something in the Punjaub.

I am charmed with your Geological part of diagram Instructions,8 but have the same fault with yours as with all— You do not give the prices of the required or recommended Instruments & books, & that, however infra-dignit:, you may think it; you surely know is a most serious defect to travellers. Did I know the price of the hand levels of Adies9 you recommend I would send for one in all probability.— What on Earth can any but a profound mineralogist understand by DelaBeches Mineralogy?—10 Pinnock’s Catechism11 would do ten times more good in the navy. All the rest I like very well. All want something. Herschells12 especially neither gives rules for calculating Bar. heights nor recommends any, & yet who can have heard of the only good ones.? (Bessells13 in the Scientific Memoirs translated by Sabine, but which it almost requires mathematical powers to use.). There is still a terrible want of real practical books on Science, (like Simms Surveying)—14 Of books from which a traveller or foreign settler shall know, how to set about his work, I speak now from a good deal of experience & can answer for it that the two great obstacles to science at our possessions abroad, are, the want of correspondents in England & the inability to procure information as to the price & makers of very trifling utensils. People especially find or think they find curious things, take the trouble of sending a long letter & specimens to an enquirer in England & have neither thanks nor notice taken of letter or gift.— Poor Williams15 complained that of all the letters he had written to the Survey but one was answered & the magnificent series of coal fossils not even acknowledged.— Do not suppose I complain for myself.— it is not the case. my correspondents I write to keep & require not answers except where specially desired

CD annotations

2.16 except … high. 2.17] double scored pencil
3.1 the Strat. … conformable 3.2] double scored pencil
6.1 I am … action,] scored pencil
10.3 however … travellers. 10.4] double scored pencil


Hooker had spent twenty days exploring the Donkia pass, unknown to Europeans, camping at Momay Samdong, 15,362 ft (J. D. Hooker 1854, 2: 117–44). He left Momay on 30 September to return to the village of Yeumtong, en route to join Archibald Campbell at Choongtam (ibid., p. 145).
John McClelland was junior member and secretary of a committee for the investigation of the mineral resources of India.
An allusion to the Geological Society of London, whose fellows had frequently debated whether foliated rocks were aqueous or metamorphic in origin and also the relationship between foliation and cleavage. CD discussed his own theories in South America, pp. 165–6.
South America, p. 143, in which CD gave a diagram of a fragment of gneiss embedded in another variety of the same rock.
The Kinchinjhow glacier and the Donkia glaciers are described in J. D. Hooker 1854, 2: 133–8.
John Grant Malcolmson had died in Dhoolia, India, in 1844 (Gentleman’s Magazine n.s. 21 (1844): 670).
Lord Dalhousie, governor-general of India.
The Admiralty manual, Herschel ed. 1849.
Alexander James Adie, Scottish instrument maker (see letter to Robert Chambers, [14 February – 20 March 1848], n. 2). Hooker was, at that time, experiencing great practical problems with his own instruments: one barometer could not cope with the cold; a thermometer broke when a tripod collapsed; and he had to keep calibrating and adjusting for the altitude against readings taken at Calcutta. In an appendix to J. D. Hooker 1854, Hooker discussed the merits of various instruments for high altitude work.
Henry Thomas De la Beche wrote the chapter on mineralogy for the Admiralty manual (Herschel ed. 1849).
Pinnock 1821. William Pinnock wrote a series of elementary ‘catechisms’ on a wide range of subjects in the early part of the nineteenth century.
John Frederick William Herschel wrote the chapter on meteorology for Herschel ed. 1849.
Friedrich Wilhelm Bessel, whose paper ‘On barometrical measurement of heights’ from the Astronomische Nachrichten was translated by Edward Sabine in Richard Taylor’s Scientific Memoirs (Bessel 1841).
David Hiram Williams, of the Geological Survey of India, who had died early in 1849. Before working in India, he had been employed by the Geological Survey of Great Britain (see letter from J. D. Hooker, 20 February – 16 [March] 1848, n. 3).


Bessel, Friedrich Wilhelm. 1841. On barometrical measurement of heights. (Translated from the Astronomische Nachrichten, nos. 356, 357.) Scientific Memoirs, selected from the transactions of foreign academies of science and learned societies, and from foreign journals 2: 517–50.

Pinnock, William. 1821. A catechism of mineralogy. 4th ed. London.

Simms, Frederic Walter. 1837. A treatise of the principles and practice of levelling … particularly in the construction of roads; with Mr Tetford’s rules for the same. London.

South America: Geological observations on South America. Being the third part of the geology of the voyage of the Beagle, under the command of Capt. FitzRoy RN, during the years 1832 to 1836. By Charles Darwin. London: Smith, Elder & Co. 1846.


CD partly right. JDH was calling "stratification" what CD calls "foliation". Answers CD’s question on cleavage foliation in Himalayas. Glacial action.

Charmed by CD’s Admiralty instructions on geology [in Manual of scientific enquiry (1849), Collected papers 1: 227–50], but complains he does not give prices of books and instruments he recommends.

Letter details

Letter no.
Joseph Dalton Hooker
Charles Robert Darwin
Sent from
Camp Sikkim, Himalayas
Source of text
Royal Botanic Gardens, Kew (India letters 1847–51: 217–18 JDH/1/10)
Physical description
inc ?

Please cite as

Darwin Correspondence Project, “Letter no. 1257,” accessed on 20 July 2024,

Also published in The Correspondence of Charles Darwin, vol. 4