[[1]]
Camp Thibet [Tibet] frontier
Sikkim Himal
Sept[ember] 30/ [18]49
Carissimo Darwin
Motive for the 2d Edition
of Darwin's Geolog[y] of
S. America.
Stratification is vexation,
Foliation's twice as bad;
Where joints there be,
They puzzle me;
And Cleavage drives me mad.
Dear [Charles] Darwin
I have been reading your Geology of S[outh]. Am[erica]. 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
different differing in relative amount of Quartz Mica or Feldspar, & which strata are
further foliated or stratified throughout. To begin at the beginning I [1 word crossed
out, illeg.] 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
[[2]] 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 *1 writes me that he finds
the same in the Curruckpore range (S. of the Ganges) substituting I think
Hornblende for Mica schist. 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
[[3]] index of the deposition of the folia from water but being a sneering skeptic[sic] I
kept my heresy to myself & was not going to break my head against the stony
gizzards of Deans & Doctors. 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 [1 word crossed out,
illeg.] 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 laminae foliate round these ellipsees[sic], 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 both 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>
[[4]] 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 plates beds an inch or so thick of Q. & F. always like beads soldered
(or my lenses) [1 word crossed out, illeg.] together. The black lines here represent
the micah. [Sketch of sediment layers appears here]
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 came down
from the Mts. & I could not be positive which was the vein--but that one stratified
foliated rock enclosed another was as clear as in your sketch of the Rio rock.
[Sketch of rocks appear here with the labels "block of Gneiss" and "vein?"] A long
story again arises out of the formation chrystallization & I take it rechrystallization of
the Garnets & their arrangement now in veins
[[5]] & 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.
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 sceptical[sic] 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[outh]. Am[Erica]. Geolog[y].
in which I assure you I have been deeply interested, it is a most
[[6]] 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 Malcolmson *2 --I think he is alive if there be not two such
men. entre nous he is said to drink -- Lord D. *3 has appointed him something in the
Punjaub [Punjab].
I am charmed with your Geological part of [DIAG] Instructions *4, 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 Adies *5 you recommend I would send for one in all probability.-- What
on Earth can
[[7]] any but a profound mineralogist understand by DelaBeches *6 Mineralogy? -f10 Pinnock's Catechism *7 would do ten times more good in the navy. All the rest I
like very well. All want something. Herschells *8 especially neither gives rules for
calculating Bar. heights nor recommends any, & yet who can have heard of the only
good ones.? (Bessellsf13 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) -- 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 Williams *9 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[.] *10
ENDNOTES
1. John McClellend.
2. John Grant Malcolmson.
3. Lord. Dalhousie (James Broun-Ramsay, 1st Marquess of Dalhousie) Governor -General of India.
4. The Admiralty manual, Herschel ed. 1849.
5. Alexander James Adie.
6. Henry Thomas De la Beche.
7. William Pinnock.
8. Friedrich Wilhelm Bessel.
9. David Hiram Williams.
10. The letter concludes here, though it is unsigned it is written in the hand of Joseph
Dalton Hooker.
Please note that work on this transcript is ongoing. Users are advised to study
electronic image(s) of this document where possible.