RECORD: Darwin, C. R. 5.1834. Geological diary: Gregory Bay. CUL-DAR34.183. Edited by John van Wyhe (Darwin Online,

REVISION HISTORY: Transcribed by Kees Rookmaaker, corrections by John van Wyhe 4.2011, 2015. 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.


May 28th 1834. — Gregory Bay

The low cliffs are composed chiefly of blackish hard mud full of fragments & rolled pieces of slate & syenite, some of greenstone; a few of serpentine feldspathic rock & conglomerate. chiefly in size walnut to turnip; occasionally size of mans head. — sometimes interstratified with masses of yellow sandy clay with lines of pebbles & curved plates of fine gravel. —

Two sections much interested me. in one, blackish sandy clay, very finely & much laminated (D) (Fig 1), was interstratified with yellow more sandy clay (B) also much more laminated, (laminae more un even) these beds dipped to the NW by W at ∠ 65°. —

The difference of color. straightness & high inclination of line of separation rendered this very curious & immediately brought to mind the cleavage of the old slates:

The chief part of cliff was composed of this yellow sandy clay, which at right hand contained large pebbles & lost its stratification

The black clay, in its upper part, became [sentence unfinished]

183 verso

Even in the straight beds of the blackish clay: the layers were often involuted.

Very like generally in shape to clay slate & quartz South of Las Minas.

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Citation: John van Wyhe, ed. 2002-. The Complete Work of Charles Darwin Online. (

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