From David Forbes [after 11 December 1860]1
and is about finished—
The question you ask me about the glacial action I can only answer as follows—2
From Lat. 13o to lat 30o there is a plateau or rather indistinct remains of one at about 12000 feet elevation composed of debris such as would generally be ascribed to ice action— the rocks are in many parts especially lat 15o 16o. 17o. 18o S. strongly furrowed & grooved similar to those of Norway.3 the grooves have a general direction and the debris from the plateau in question contains rolled and marked or grooved & scratched pebbles— down where you observed the mass of debris in question,4 the remains of the plateau is only distinct in spots evidently from the river action, but only some 15 leagues north of same I found it grandly developed—and could not explain it at all untill my later examination of the chain of the Andes northward up to Lat 13. showed me at spots (barometrical measurements) a similar development connecting same with the great Eastern Andean plateau of Silurian debris, described in section— I was informed that a little south of Cauquenes, there exist real glaciers in the Andes—but I found none north of same— my information was tolerably reliable
As I believe fully in your theory of the origin of species I shall be glad to do anything for you in advancing same and shall attend to the questions you send me and send you answers as soon as possible If you have more points I shall attend to them if you drop me a line— The question you ask me about the Chilean breed of sheep—I can in part answer now—5
I was also struck with this and at 2 haciendas I staid at endeavoured to come to the bottom of this but not satisfactorily.— The prevalent opinion is that the race was originally derived from an intermixture of sheep & goat but as far as I could discover, it is nowhere now produced from this source—and the flocks at all the haciendas I saw are only ofspring of similar sheep and not artificially produced as the mules— One Haciendado at Mendoza stated that, altho if I asked every other Haciendado—in the province they would tell me it was a cross he never knew such a case to have actually occurred & stated his belief that they were a distinct race of sheep
One would think it had been easy to have sifted such a simple question but I did not succed— would an examination (microscopic) of the hair be of service— I could send you some as I have a saddle cover here in Birmingham of this article.—6
There is one point I would direct your attention to it is the horse— The horse of S America was originally Spanish or Andalusian—but now presents 3 wonderfully different variety
1. Chilian—exactly same as true Andalusian
2. Pampa horse you know
3. Puno horse—a most strange sort of small horse, slender narrow chested & very peculiar altogether—evidently owing to the rarified atmosphere—7 I believe I can prove a great change from same cause in the Puno Indians (Aymara) whom I found to be structurally different. for example femur longer than tibia, &c.8
Yours very truly | David Forbes
CD annotations
Footnotes
Bibliography
Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.
DNB: Dictionary of national biography. Edited by Leslie Stephen and Sidney Lee. 63 vols. and 2 supplements (6 vols.). London: Smith, Elder & Co. 1885–1912. Dictionary of national biography 1912–90. Edited by H. W. C. Davis et al. 9 vols. London: Oxford University Press. 1927–96.
Forbes, James David. 1861. On the climate of Edinburgh for fifty-six years, from 1795 to 1850, deduced principally from Mr Adie’s observations; with an account of other and earlier registers. Transactions of the Royal Society of Edinburgh 22: 327–56.
Origin 3d ed.: On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. 3d edition, with additions and corrections. By Charles Darwin. London: John Murray. 1861.
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.
Variation: The variation of animals and plants under domestication. By Charles Darwin. 2 vols. London: John Murray. 1868.
Summary
Glacial action in the Andes.
Origin of Chilean sheep.
Varieties of S. American horses.
Letter details
- Letter no.
- DCP-LETT-2621
- From
- David Forbes
- To
- Charles Robert Darwin
- Sent from
- unstated
- Source of text
- DAR 164: 150
- Physical description
- ALS 2pp inc †
Please cite as
Darwin Correspondence Project, “Letter no. 2621,” accessed on 26 September 2022, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-2621.xml
Also published in The Correspondence of Charles Darwin, vol. 8