RECORD: Darwin, C. R. Geological diary: St Pauls (2.1832) CUL-DAR32.37-38 Transcribed by Kees Rookmaaker, edited by John van Wyhe . (Darwin Online, http://darwin-online.org.uk/).
REVISION HISTORY: Transcribed from microfilm by Kees Rookmaaker, corrections by John van Wyhe and Gordon Chancellor 5.2010. RN3
NOTE: This document, part of the largest scientific document composed by Darwin during the voyage of the Beagle, is written mostly in ink. Where pencil was used instead this is noted in the textual notes. Marginal notes are here integrated into the text.
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Reproduced with the permission of the Syndics of Cambridge University Library and William Huxley Darwin.
1832 Feb 16th St. Pauls 23
This small Island lies in 0.58' N. & 29° 15' West longitude. The total circumference is barely 3/4 of a miles, the highest eminence about 50 feet above the sea. — It may be considered as the peak of a submarine mountain. At 1/4 of a mile distance, no bottom could be found, excepting on the West, where it shelved a little. Apparently in most places the sides are perpendicular beneath the sea. — The rocks are serpentine. & in the lower parts mixed with much Diallage. — the whole island is intersected with veins or beds of various substances. 235...239 — The serpentine. contain Feldspar, Chlorite & traces of Copper. — The diallage 242...245, contains [illeg]. Feldspar. Mica Serpentine & Chlorite. — This rock weathers in a curious manner. owing to the washing away of minute veins of Serpentine. —
The third rock 240 & 241 is much veined with serpentine I am ignorant of its nature. The veins or beds are of three sorts. — One 252-253 of a decomposing vesicular mineral. infusible not effervescing with Acids: 2d a conglomerate of Diallage. with a matrix of the same. — does not effervesce. with acids. — 246-248 this ought rather to be considered as a bed (?) instead of vein: it dips to the S. & was only place where I could see anything like stratification. —
3d sort is a conglomerate of diallage &
(a) the action of the weather has a curious effect on the serpentine rock. the outside in many places with a white mineral with an unctuous feel. — This cause give the island at a short distance a very white appearance. — which has by navigators been solely attributed to birds dung. —
(b) The perpendicular face of the rock although exposed to the full force of the Atlantic. swell which even on the calmer days is considerable, is yet matted with Fuci Zoophite & shells. — Is not this a strong proof
t what little power pure water by itself has of wearing away the surfaces of rocks. Vide "Cuviers theory of earth"1 on this subject
1 Cuvier 1817.
1832 Feb. 16th St. Pauls 24
Feldspar in a hard calcareous base. — Perhaps this latter one may be of a different origin from the other two. 249..251 — The
latter former ones from their numbers & the manner, in which they are interlaced I should think were formed at the same time as the rock.
The Serpentine or
cleavage Diallage (a) is much divided by cleavage. which is in a perpendicular direction. — The Island. in works of navigation has wrongly been described as consisting of several distinct rocks. — It is nearly circular with a large oval opening in centre through which the sea flows. — There are a few small outlying rocks. —
This little speck in the Atlantic (b) is 350 miles from the nearest land, which is the island Fernando Noronha. & 540 from the coast of S America. —
I will here add the few other observations I made. — The island is entirely destitute of vegetation: it affords a secure a building place for countless numbers of boobys & noddys: They hitherto have had so little cause to dread man, that we killed numbers with my geological hammer. — The Boobys lay their eggs on the bare ground; the noddys make a sort of
orpi nest with sea-weed. — By the side of the female noddy on the nest, there generally was lying a small flying fish. It was very amusing to see the large crabs with which the rock is covered, quietly
1832 Feb. 16th St. Pauls 25
stealing them. — The only other inhabitants were numbers of [Flies]
& Ornithomya. the latter on the bodies of the Boobys. — I think it is
a new species. — There were several spiders. A Staphylinus in the dung. &
a small brown moth. — What this latter isolated little being found to live-on
I am quite at a loss even to guess. — I believe what I have mentioned is the
whole Fauna of the Island of St Pauls. — Whilst
I we were busy in collecting
the birds & their eggs. the men in boats caught numbers of fine fish.
& had it not been for the vast numbers of sharks they would have soon
filled the boat. —
Is not this the first Island in the Atlantic which has been shown not to be of Volcanic origin? —
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Citation: John van Wyhe, editor. 2002-. The Complete Work of Charles Darwin Online. (http://darwin-online.org.uk/)
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