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Darwin Correspondence Project

From Charles San Lambert1   [c. July 1835]

You travel upwards in that dry ravine [Santandrés] for about 3 miles, where it ends, & on the summit of the hill which forms its boundary, you find large superficial beds of Sulphur & the Sulphate of Alumina.— In the ravine there are scattered about fragments of Pumice Lavas calcinèe Granite & Porphyry & other Volcanic productions.— The formation of all the country from Sant Andrès is generally of Granite & Porphyry covered by Volcanic eruptions. These substances present generally a red appearance, whilst the Granite & Porphyry formation on which they lay is black.— There are many points, where you can see the points of the Granitic hills rise in the middle of the Volcanic formation; the Lava not being in sufficient quantity to cover the whole.— All the ravines have been formed after the eruptions of the Lava.— This Volcanic formation extends from Copiapò to Atacama, forming in some places regular basaltic elevated plains. These detain the waters which flow from the Western side of the Cordilleras & cause those Salt lakes, where the inhabitants of Copiapò & Atacama provide themselves with that article.

CD annotations

‘It must be remarked, that Mr Lambert’s statement that the Volcanic eruptions capped the hills prior to the excavation of the Valleys is in perfect accordance with my idea that the Tufa is submarine formation & not subaerial if subaerial, there is no possible reason for imagining why all the patches should have belonged to one level.—’


Mr Lambert is mentioned in South America, p. 211. This letter is used on p. 220.


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.


Describes volcanic formations capping granite hills from Copiapò to Atacama [Chile]. [See South America, pp. 230–1.]

Letter details

Letter no.
Charles San Lambert
Charles Robert Darwin
Sent from
Source of text
DAR 37: 648
Physical description
CC 2pp, CD note

Please cite as

Darwin Correspondence Project, “Letter no. 279,” accessed on 25 June 2022,

Also published in The Correspondence of Charles Darwin, vol. 1