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

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

NOTE: See record in the Darwin Online manuscript catalogue, enter its Identifier here. 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.

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

62 verso

(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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