RECORD: Darwin, C. R. Geological diary: Coast of Patagonia. (8-9.1832) CUL-DAR32.61-62 Transcribed by Kees Rookmaaker, edited by John van Wyhe (Darwin Online,

REVISION HISTORY: Transcribed from the microfilm by Kees Rookmaaker, corrections and editing by John van Wyhe 5-6.2010, corrected against the manuscript by van Wyhe 7.2010. RN2

NOTE: This document, part of the largest scientific document composed by Darwin during the voyage of the Beagle, is written mostly in ink. 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.

See the introduction to the Geological Diary by Gordon Chancellor.



1832 Aug: Sept: Coast of Patagonia


Sailing from Buenos Ayres to a little north of Cape Corrientes the coast is singularly void of any sort of interest. — In its appearance it resembles that of the Province of M: Video. which consisting of Mica slate by its degradation forms quantities of sand. This is collected by the action of the winds & forms dunes. — Falkner1 states that the Pampas do not extend to the SE of Buenos Ayres but that hills, covered with wood, run in E. W direction through this tract of country. — (?) These in all probability are the same as those on the northern bank of the Plata, which are compared of Phyllade (daubuisson) & Mica slate. —

Does not this refer to the [Tandil] ranges, placed by him far too much to the N ∴ in line with C. St Anthony.

In laititude 37° 55', a little north of Corrientes the features of the coast alter; here a perfectly horizontal line of cliffs takes the place of the monotonous chain of sand hillocks. — The cliff is about 30 or 40 feet high & perhaps is composed of clay. — Probably This formation extends probably this in W 1/2 N direction for many miles within the country. — Large outlying masses of a quadrangular figure V. Drawing, are seen a little north of where it first appears on the coast & at a considerable distance (25 miles?). — Their elevation must of course also be much greater. The great vallies which form the outlying masses appear to run in a NNE & SSW direction. — At Cape Corrientes beds of horizontally stratified rock (probably sandstone) seem to underlie (?) the great formation of clay. — SW of Corrientes Cliffs & sandy dunes alternate; but in the long E.W range before the entrance of Bahia Blanca

1 Thomas Falkner (1707-1784), Jesuit missionary in Patagonia, 1740-1768. Falkner 1774.

61 verso

N. B. For the future. the marginal letters will refer to the notes on the back of page & not on the opposite one:



1832 Sept: Octob Coast of Patagonia


it is one succession of the sand hillocks: I do not know whether to attribute the sand to the detrition of Granitic rocks or to sandstone: In Lat 38° 28' S & Long 58° 4'. a piece of Granite not rolled 693, was accidentally brought up from the bottom. — Along this whole line of coast the water deppens but very gradually; opposite to the cliffs it is deepest: the action of the tides must continually cause large masses to fall down, but this clayey substance would not so easily form protecting banks & shoals as sand produced from the detrition of rock.

Bahia Blanca

The northern shore of this bay is rather less than 30 miles along, in all this line I only found three v. notes !!! geological sections; the intervals being completely covered up by sand dunes. — The settlement or town is built on a slight elevation in an extensive plain; the rock is composed of horizontal strata of a soft spongey friable pale coloured argillaceous limestone 716, containing small pebbles of quartz & other extraneous matter. — Being there only a few hours I know nothing of its relation to the great plain: —

Punta Alta. projects into the bay & is formed of a mile of low cliffs. — it posseses great interest to the geologist from containing numerous organic remains. — The lowest bed extends horizontally for some miles at low water mark; it is a gravel of quartzy pebbles (b) cemented by calcareous matter, is hard & made up of plates, which at first sight look like stratification. — Within in some

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(a) At 30 miles distant, the sounding only give between 30 & 40 fathoms. — Is not this generally the case

(b) Specimens of this gravel may be seen adhering to the fossils: the same may be said for the "Tosca"

Is not this generally the case] added pencil.

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