skip to content

Darwin Correspondence Project

From Alcide Charles Victor Dessalines d’Orbigny   14 February 18451

Monsieur,

Je venais enfin de terminer le travail relatif à vos fossiles lorsque votre dernière lettre m’est parvenue. Je me suis empressé de rédiger mes observations générales et je vous adresse la caisse par l’entremise de M. Ballière, comme vous me l’avez demandé.

Vous remarquerez, comme je le pensais bien que votre magnifique collection de Fossile, ne montre aucune contradiction avec ce que j’ai vu en Amérique. Les différences qui pourraient exister tenaient toutes à de fausses déterminations de Mr. Sowerby. Les fossiles sont des élemens d’une valeur immense en Géologie, mais ils doivent être pris avec toutes les précautions désirables. Sans cela ils peuvent donner des resultats tout a fait opposés avec les faits. Si je me suis fait beaucoup attendre pour vos déterminations, c’est que je voulais ne pas vous donner un travail provisoire. cela m’a demandé des recherches trés longues, que je ne voulais pas néanmoins négliger, pour ne pas Vous donner des renseignemens fautifs. J’espère que vous me pardonnerez le retard, en faveur du motif qui me guidait.

Votre intéressante collection est sans contredit magnifique, et demanderait une publication spéciale faites avec tous le soin désirable—car elle peut servir de base à l’eacute;tude de l’Amérique Méridionale. Je vous engage bien à faire facon des Planches de toutes les espèces Nouvelles, afin que votre travail et le mien puisse completer la Géologie de l’amerique du sud.2 Il serait bon surtout que les fossiles fuissent représentés sur plusieurs faces et avec beaucoup de series. Des figures imparfaites ne font qu’encombrer la science sans lui servir aucunement.

Je dois à votre collection de pouvoir rectifier une erreur que j’ai commise sur l’age des grès de Concepcion,3 que j’ai placée dans les terrains tertiaires et qui d’après votre Baculite nouvelle est une dépendance des terrains Crétacés.

Pour le reste je me suis souvent trouvé embarrassé pour les noms des espèces. Lorsque Mr Sowerby avait, par exemple donné un nom connu à une espèce que je crois nouvelle, j’ai cru devoir lui donner une dénomination, mais je n’y attache aucune importance, si vous ne la conservez pas changez la ou faites ce que vous voudrez, je n’ai voulu que vous fixer, et pouvoir m’entendre avec vous s’il devenait nécessaire de vous donner de nouvelles indications sur les détails et sur l’ensemble.

Voici du reste, le resumé suivant l’age des terrains que j’ai pu reconnaitre d’après vos fossiles. En commencant par les plus inferieurs. diag Terrains Jurassiques?4 une partie de la cordillère de copiapo, l’alto de guasco, (chile) et la cordillere de coquimbo

Terrain Néocomien ou crétacé inferieur. La cordillère centrale du chile. La chaine centrale de la Tierra del Fuego. La Cordillère du Perou près de Pasco. Terrain turonien, ou craie chloritée Concepcion du chile. Cordillera de Copiapo, Cordillera de Coquimbo.

Terrain patagonieen ou Tertiaire inferieur Sur l’ocean atlantique. La Bajada de Santa fé. Baie de San Joseph. Port desire. Port St Julian. Rivière de Santa Cruz. Sur le grand océan

Chiloé; (Côte est) Huafo. Navidad. Coquimbo (couches inferieures et moyennes) Payta, la Mocha.

Tous ces fossiles ne se trouvent plus vivans dans les mers actuelles et appartenaient à une periode passée.5 Terrain Diluvien ou de L’epoque actuelle Buenos Ayres. Maldonado. Coquimbo, (couches superieures de la Plaine.).ramme

Vous voyez, par cet apercu rapide, dont vous avez les details avec mon travail, que de cette manière tout se classe sans aucune indécision et sans mélange.

Vous avez dans vos fossiles le plus beau fait que je connaisse pour prouver les mouvemens brusques de la période qui a determiné leur extinction. C’est un groupe de Crépidules. Ces coquilles sont encore réunies, telles qu’on les rencontre vivante au Callao. Le moindre mouvement, même la mort des individus si elle était survenue avant d’être enveloppée, aurait séparé les differentes coquilles qui composent le groupe. C’est un fait très curieux.6

Je serais heureux, Monsieur, si le travail que j’ai fait peut vous être utile, j’insiste encore sur l’importance de vos collections pour qu’elles soient publiées.

Veuillez, je vous prie, disposer d〈e〉 moi en toutes circonstances et me croire | Votre très humble et très | Obéissant Serviteur | Alcide d’Orbigny Paris ce 14 fevrier 1845

Votre caisse est chez M Ballière.

CD annotations

Top of first page: ‘M. Hombron | astonished at amount of my labour’ ink
‘(B. Blanca | Silurian Falkland)’7

Footnotes

For a translation of this letter, see Correspondence vol. 3, Appendix I.
CD eventually included four plates of shells in South America.
Orbigny (1835–47, vol. 3, pt 3: G’{eologie}, p. 90) had earlier described the Concepci’{o}n sandstone as Tertiary. Though CD was inclined to accept the new Cretaceous dating, he noted the possibility that the baculite may simply have been a survivor from an earlier epoch (South America, pp. 126–31).
According to CD, the shells distinguished by Orbigny as Jurassic and Turonian (Upper Cretaceous) had all come from the same deposit. CD, who preferred the term Oolitic to Jurassic, compromised on the expression ‘Cretaceo-Oolitic’ (South America, p. 216).
Orbigny (1835–47, vol. 3, pt 3: G’{eologie}, p. 191) had criticised CD’s opinion (Journal of researches, p. 423) that a few living species were to be found in the lower beds at Coquimbo. Following George Brettingham Sowerby’s species determinations, CD qualified his position in South America, pp. 128–9, and in Journal of researches 2d ed., p. 344.
Orbigny believed that the shells were joined together in a way that would have been easily disturbed, and that the molluscs were therefore still living when the sea-bed was elevated. According to CD, the molluscs appeared to have died long before the shells were lifted up (South America, pp. 46–8).
Roderick Impey Murchison and James de Carle Sowerby considered CD’s Falklands specimens to be Silurian (Journal of researches, p. 253). The specimens were later described and dated by John Morris and Daniel Sharpe (Morris and Sharpe 1846). Three were described as Silurian and three as resembling Devonian forms. CD summarises the results in ‘On the geology of the Falkland Islands’, Collected papers 1: 203–4.

Translation

From Alcide Charles Victor Dessalines d’Orbigny   14 February 18451

Dear Sir,

I had at last come to the end of the work on your fossils when your last letter reached me. I have hurried to draw up the general observations, and I send you the box by way of M. Ballière as you requested.

You will observe that, as I expected, your magnificent collection of fossils shows no contradiction with those that I saw in America. The apparent differences were entirely owing to the incorrect determinations of Mr. Sowerby. Fossils are elements of immense value in geology, but they should be taken with every appropriate precaution. Failing that they will give results entirely opposed to the facts. If I kept you waiting a long time for your results, it is because I did not want to give you provisional work. This required very long searches which I would not wish to neglect to avoid giving you faulty information. I hope you will pardon the delay in view of the motive that guided me.

Your interesting collection is without question magnificent, and I would recommend a special publication produced with all due care for it can serve as a basis for the study of South America. I urge you to have the plates made of all the new species so that your work and mine can complete the geology of South America.2 Above all it would be good if the fossils could be represented from several angles and in many series. Imperfect drawings can only burden science without doing any good whatever.

I owe to your collection the opportunity to correct an error that I committed concerning the age of the sandstone of Concepcion;3 I had placed it in the Tertiary, but, according to your new Baculite, it belongs to the Cretaceous.

Furthermore, I often found myself troubled by the names of species. For example when Mr Sowerby had given a familiar name to a species that I considered to be new, I believed I ought to give it a new designation, but I attach no importance to whether you keep it or not, change it or do as you please; I wanted only to call your attention to them and to be able to know what you referred to if it became necessary to give you additional information on the details and on the whole collection.

Finally, here is the summary showing the age of the formations which I was able to recognize according to your fossils. It begins with the lowest.

Jurassic Period 4 A part of the Cordillera of Copiapo, the Alto of Guasco (Chile) and the Cordillera of Coquimbo Neocomian Period or lower Cretaceous. The central Cordillera of Chile, the central chain of Tierra del Fuego, the Cordillera of Peru near Pasco. Turonian Period, or chalk chlorite. Concepcion du Chile. Cordillera of Copiapo, Cordillera of Coquimbo. Patagonian Period or lower Tertiary. On the Atlantic Ocean. La Bajada de Santa Fe. St. Joseph’s Bay. Port Desire. Port St Julien River of Santa-Cruz. By the great ocean Chiloe (east coast) Huafo. Navidad. Coquimbo (lower and middle layers) Payta, La Mocha.

All these fossils are no longer found in the seas today; they belong to a past era.5 Diluvial Period or from the modern epoch. Buenos Ayres. Maldonado. Coquimbo, (upper levels of the plain).

With this rapid summary, the details of which you have in my book, you see that in this manner everything is classified without indecision or confusion.

You have among your fossils the most beautiful fact that I know of to prove the abrupt changes of the period in which they became extinct. It is a group of Crépidules. These shells are still joined together, just as one finds them now alive at Callao. The least change, even the death of individuals, if it occurred before they were covered over would have separated the different shells that compose the group. It is a very curious fact.6

I should be happy, Sir, if the work can be useful to you, I insist again on the importance of your collections so that they may be published.

Please, I beg of you, to make use of me under any circumstances and believe me.

Your very humble and very | Obedient Servant | Alcide d’Orbigny

Paris, 14 February 1845

Your box is at M. Baillière’s.

Footnotes

For the transcription of this letter in the original French and CD’s annotations, see Correspondence vol. 3, pp. 143–5.
CD eventually included four plates of shells in South America.
Orbigny (1835–47, vol. 3, pt 3: G’{eologie}, p. 90) had earlier described the Concepci’{o}n sandstone as Tertiary. Though CD was inclined to accept the new Cretaceous dating, he noted the possibility that the baculite may simply have been a survivor from an earlier epoch (South America, pp. 126–31).
According to CD, the shells distinguished by Orbigny as Jurassic and Turonian (Upper Cretaceous) had all come from the same deposit. CD, who preferred the term Oolitic to Jurassic, compromised on the expression ‘Cretaceo-Oolitic’ (South America, p. 216).
Orbigny (1835–47, vol. 3, pt 3: G’{eologie}, p. 191) had criticised CD’s opinion (Journal of researches, p. 423) that a few living species were to be found in the lower beds at Coquimbo. Following George Brettingham Sowerby’s species determinations, CD qualified his position in South America, pp. 128–9, and in Journal of researches 2d ed., p. 344.
Orbigny believed that the shells were joined together in a way that would have been easily disturbed, and that the molluscs were therefore still living when the sea-bed was elevated. According to CD, the molluscs appeared to have died long before the shells were lifted up (South America, pp. 46–8).

Summary

Agrees that CD’s fossil shells do not differ from those ADd’O saw in South America. Apparent differences due to errors by G. B. Sowerby. Collection magnificent; recommends special publication. Enabled ADd’O to correct error in dating of sandstone of Concepción. Lists geological periods represented in collection from Jurassic to Diluvian. Collection includes unusual group of crepidules.

Letter details

Letter no.
DCP-LETT-829
From
Alcide Charles Victor Dessalines (Alcide) d’Orbigny
To
Charles Robert Darwin
Sent from
Paris
Source of text
DAR 43.1: 62–5
Physical description
7pp † (French)

Please cite as

Darwin Correspondence Project, “Letter no. 829,” accessed on 16 September 2019, https://www.darwinproject.ac.uk/letter/DCP-LETT-829.xml

Also published in The Correspondence of Charles Darwin, vol. 3

letter