RECORD: Darwin, C. R. [1836]. rough hand-drawn and water-coloured sketch of elevations of coral reef. CUL-DAR44.25. (John van Wyhe ed., 2002-. The Complete Work of Charles Darwin Online, http://darwin-online.org.uk/)

REVISION HISTORY: Transcribed and edited by John van Wyhe 2024. With thanks to Gordon Chancellor. RN1

NOTE: See record in the Darwin Online manuscript catalogue, enter its Identifier here. Reproduced with the permission of the Syndics of Cambridge University Library and William Huxley Darwin. The volume CUL-DAR44 contains maps of South America, plans, diagrams and geological sections etc. drawn by Darwin.

Introduction

These six partially watercoloured pencil sketches are filed in the Darwin Archive next to the coloured sections of Keeling (CUL-DAR44.24) which have become the classic illustrations of Darwin's coral reef theory. However, there are important differences that suggest this sheet may belong with the 'Coral Islands' essay rather than with the Keeling notes. First of all, five of those here represent a mountainous island with an encircling reef and lagoon, like Tahiti, rather than a low coral atoll like Keeling. Compare those below with the sketches in the 'Coral Islands' essay in CUL-DAR41.15v. Here Darwin contrasts islands with steep angles descending into the sea versus shallow angles. The two sheets were not done at the same time; they are on different paper types, CUL-DAR44.24 was sketched in ink and these in pencil. New Holland is mentioned here and in the 'Coral Islands' essay. The focus of the Keeling sections is closer to the surface whereas these portray a much greater scale of depth. Perhaps this indicates more of a focus on subsidence than on the details of reef construction in the Keeling sketches. Incomplete shield of 'G WILMOT 1834', 21x26cm.

[25]

 [above 1st sketch:] (A) IV | [Allen] | Margin | Level of the sea

[below 1st sketch:] draw this one not the subsided | 100 fathoms 100

[above 2nd sketch:] (B) III (b) (a) | Reef | 20 fathoms | Limit at [2 words illeg] | Level of sea [below 2nd sketch:] Describe this if subsided like reefs of New Holland [3rd sketch:] III (b) [4th sketch:] Calculate land under 20º degrees at 4 miles distance depth. | 20º 4 miles ?

[25v]

[1st sketch:] (A) | Reef | Level of the sea | 100 fathoms

[2nd sketch:] (B) | Reef | 30 Fathoms

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Citation: John van Wyhe, ed. 2002-. The Complete Work of Charles Darwin Online. (http://darwin-online.org.uk/)

File last updated 8 February, 2026