RECORD: Darwin, C. R. Geological diary: Gregory Bay. (5.1834) CUL-DAR34.183 Transcribed by Kees Rookmaaker, edited by John van Wyhe (Darwin Online,

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


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 uneven) 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, editor. 2002-. The Complete Work of Charles Darwin Online. (

File last updated 27 November, 2015