More Letters of Charles Darwin Volume I [16]
period. The conclusion of my excursion was very unfortunate, I became unwell and could hardly reach this place. I have been in bed for the last month, but am now rapidly getting well. I had hoped during this time to have made a good collection of insects but it has been impossible: I regret the less because Chiloe fairly swarms with collectors; there are more naturalists in the country, than carpenters or shoemakers or any other honest trade.
In my letter from the Falkland Islands I said I had fears about a box with a Megatherium. I have since heard from B. Ayres that it went to Liverpool by the brig "Basingwaithe." If you have not received it, it is I think worth taking some trouble about. In October two casks and a jar were sent by H.M.S. "Samarang" via Portsmouth. I have no doubt you have received them. With this letter I send a good many bird skins; in the same box with them, there is a paper parcel containing pill boxes with insects. The other pill boxes require no particular care. You will see in two of these boxes some dried Planariae (terrestrial), the only method I have found of preserving them (they are exceedingly brittle). By examining the white species I understand some little of the internal structure. There are two small parcels of seeds. There are some plants which I hope may interest you, or at least those from Patagonia where I collected every one in flower. There is a bottle clumsily but I think securely corked containing water and gas from the hot baths of Cauquenes seated at foot of Andes and long celebrated for medicinal properties. I took pains in filling and securing both water and gas. If you can find any one who likes to analyze them, I should think it would be worth the trouble. I have not time at present to copy my few observations about the locality, etc., etc., [of] these springs. Will you tell me how the Arachnidae which I have sent home, for instance those from Rio, appear to be preserved. I have doubts whether it is worth while collecting them.
We sail the day after to-morrow: our plans are at last limited and definite; I am delighted to say we have bid an eternal adieu to T. del Fuego. The "Beagle" will not proceed further south than C. Tres Montes; from which point we survey to the north. The Chonos Archipelago is delightfully unknown: fine deep inlets running into the Cordilleras--where we can steer by the light of a volcano. I do not know which part of the voyage now offers the most attractions. This is a shamefully untidy letter, but you must forgive me.
LETTER 6. TO J.S. HENSLOW. April 18th, 1835. Valparaiso.
I have just returned from Mendoza, having crossed the Cordilleras by two passes. This trip has added much to my knowledge of the geology of the country. Some of the facts, of the truth of which I in my own mind feel fully convinced, will appear to you quite absurd and incredible. I will give a very short sketch of the structure of these huge mountains. In the Portillo pass (the more southern one) travellers have described the Cordilleras to consist of a double chain of nearly equal altitude separated by a considerable interval. This is the case; and the same structure extends to the northward to Uspallata; the little elevation of the eastern line (here not more than 6,000-7,000 feet.) has caused it almost to be overlooked. To begin with the western and principal chain, we have, where the sections are best seen, an enormous mass of a porphyritic conglomerate resting on granite. This latter rock seems to form the nucleus of the whole mass, and is seen in the deep lateral valleys, injected amongst, upheaving, overturning in the most extraordinary manner, the overlying strata. The stratification in all the mountains is beautifully distinct and from a variety in the colour can be seen at great distances. I cannot imagine any part of the world presenting a more extraordinary scene of the breaking up of the crust of the globe than the very central parts of the Andes. The upheaval has taken place by a great number of (nearly) N. and S.
In my letter from the Falkland Islands I said I had fears about a box with a Megatherium. I have since heard from B. Ayres that it went to Liverpool by the brig "Basingwaithe." If you have not received it, it is I think worth taking some trouble about. In October two casks and a jar were sent by H.M.S. "Samarang" via Portsmouth. I have no doubt you have received them. With this letter I send a good many bird skins; in the same box with them, there is a paper parcel containing pill boxes with insects. The other pill boxes require no particular care. You will see in two of these boxes some dried Planariae (terrestrial), the only method I have found of preserving them (they are exceedingly brittle). By examining the white species I understand some little of the internal structure. There are two small parcels of seeds. There are some plants which I hope may interest you, or at least those from Patagonia where I collected every one in flower. There is a bottle clumsily but I think securely corked containing water and gas from the hot baths of Cauquenes seated at foot of Andes and long celebrated for medicinal properties. I took pains in filling and securing both water and gas. If you can find any one who likes to analyze them, I should think it would be worth the trouble. I have not time at present to copy my few observations about the locality, etc., etc., [of] these springs. Will you tell me how the Arachnidae which I have sent home, for instance those from Rio, appear to be preserved. I have doubts whether it is worth while collecting them.
We sail the day after to-morrow: our plans are at last limited and definite; I am delighted to say we have bid an eternal adieu to T. del Fuego. The "Beagle" will not proceed further south than C. Tres Montes; from which point we survey to the north. The Chonos Archipelago is delightfully unknown: fine deep inlets running into the Cordilleras--where we can steer by the light of a volcano. I do not know which part of the voyage now offers the most attractions. This is a shamefully untidy letter, but you must forgive me.
LETTER 6. TO J.S. HENSLOW. April 18th, 1835. Valparaiso.
I have just returned from Mendoza, having crossed the Cordilleras by two passes. This trip has added much to my knowledge of the geology of the country. Some of the facts, of the truth of which I in my own mind feel fully convinced, will appear to you quite absurd and incredible. I will give a very short sketch of the structure of these huge mountains. In the Portillo pass (the more southern one) travellers have described the Cordilleras to consist of a double chain of nearly equal altitude separated by a considerable interval. This is the case; and the same structure extends to the northward to Uspallata; the little elevation of the eastern line (here not more than 6,000-7,000 feet.) has caused it almost to be overlooked. To begin with the western and principal chain, we have, where the sections are best seen, an enormous mass of a porphyritic conglomerate resting on granite. This latter rock seems to form the nucleus of the whole mass, and is seen in the deep lateral valleys, injected amongst, upheaving, overturning in the most extraordinary manner, the overlying strata. The stratification in all the mountains is beautifully distinct and from a variety in the colour can be seen at great distances. I cannot imagine any part of the world presenting a more extraordinary scene of the breaking up of the crust of the globe than the very central parts of the Andes. The upheaval has taken place by a great number of (nearly) N. and S.