Darwin's notes on the geology of Galápagos

An introduction by K. Thalia Grant and Gregory B. Estes

This is an introduction to an annotated transcription of Darwin's geological notes from Galápagos, with a geographical orientation to the land formations described within.

The original manuscript pages are bound in a volume of Darwin's geological observations from Galápagos, Tahiti and New Zealand. This volume (entitled DAR 37.2) and a volume of Darwin's earlier geological observations from northern Chile and Peru (DAR 37.1) are catalogued together, in the Darwin Archive of Cambridge University Library, as "DAR 37. Notes on the geology of places visited on the voyage. Part IV".

Most of the pages consist of sheets of paper folded in half to make four writing surfaces. The remaining pages consist of single, unfolded pieces of paper. The width of the pages varies between 14 cm and 20.5 cm and the height ranges from 15.5 cm to 32 cm.

The pages were first transcribed by the authors in 1996 and used, together with Captain FitzRoy's log of HMS Beagle and charts of the archipelago, to retrace Darwin's footsteps in Galápagos.¹ The information was invaluable in determining where Darwin stepped ashore, which geological features he examined and the route he took to reach them. It was also used extensively in researching his geological discoveries.² The transcription has never been published in full until now.

There are two parts to Darwin's Galápagos geology notes; the pages he wrote while in the Galápagos islands (15 September - 20 October 1835), and those he wrote after reflection, on the passage home. It is clear that Darwin wrote the second part after he left Galápagos because there are references within these pages to the Low archipelago and Tahiti, which Darwin visited in November 1835. He most likely wrote these pages during the first half of 1836, as suggested by the following excerpt from one of his letters to his sister Caroline, dated April 29, 1836, and posted from Mauritius.

"Whilst we are at sea, & the weather is fine, my time passes smoothly, because I am very busy. My occupation consists in rearranging old geological notes: the rearranging generally consists in totally rewriting them."³

References to Ascension Island, which Darwin explored in July 1836, and to Notebook A, which Darwin wrote between 1837 and 1838, were clearly added later.⁴

Pagination

In total there are 121 pages of CUL-DAR37 that have notes on or related to the geology of Galápagos. Thirty-seven sketches and diagrams are also included in these pages. Eighty-one of the pages are numbered with two distinct numbers –a "small" number between 1 and 49 written in ink, and a "large" number between 716 and 795, added in pencil. Both sets of numbers are found on the upper right hand side of the page. In most cases the small number is separated from the large number by a single bracket.

There are three sets of small numbers and they define three sections of the Galápagos manuscript. In the bound volume of CUL-DAR37, the first section (labeled pages 1-10) consists of notes about James Island (Santiago). These pages, each measuring 20 x 32 cm, were almost certainly written on land when Darwin was camped on James Island. The second section (pages 1-20) consists of notes about Chatham (San Cristóbal), Charles (Floreana) and Albemarle (Isabela) islands, in that order. They were most likely written on board the Beagle within a few days of Darwin making his corresponding shore excursions. These pages each measure 16 x 20 cm. In chronological order of Darwin's explorations in Galápagos this second section should precede the first section, for Chatham was the first island Darwin visited, and James was the last. These first two sections comprise the notes Darwin wrote while he was still in Galápagos. Many of the pages have a large X or several squiggly lines through them, presumably marked by Darwin as he read through them to rewrite them.

The third section (pages 1-49) was written after Galápagos and consists of a re-treatment of Charles, Chatham, Albemarle and James (beginning with the most Southerly islands and proceeding northwards, as Darwin intended), notes on places that Darwin did not visit but saw from the Beagle or learned about from the ship's surveying officers, and a general overview of the archipelago. These pages measure 20.5 x 25.5 cm, and have a running, underlined heading of "Galapagos Islands". The year 1835 is also recorded in the top left hand corner of most pages. The first two pages of this third section are both labeled number 1 and contain similar information. Three pages are labeled 41bis.

The second set of numbers runs from 716 to 795, and was added at a later date by an archivist. (Notes Rookmaaker and van Wyhe) These page numbers indicate their place within Darwin's complete Geological diary from the voyage (CUL-DAR34-38, pages 1-960). His James Island notes have for some reason been catalogued as before his notes on Chatham, Charles and Albemarle. Pages 722 and 723 are incorrectly numbered. That is, the page that is labelled 723 (7) should precede page 722 (8), according to both Darwin's original numbering system and the content of the pages.

Orthography

The following transcription copies Darwin's orthography. Spelling mistakes are not corrected, underlines and abbreviations are kept, and insertions and deletions are noted. Darwin consistently misspelled some words, such as the island of Albemarle, which he spelled as "Albermale" or "Albermales". His other spelling mistakes include: neighbourhead, occassionally, broard, weekness, untill, escarpement and doones (dunes). He was inconsistent in his spelling of color, neighboring, separated and Wenman; sometimes spelling them as colour, neighbouring, seperated and Wenams. He spelled the word dyke once as dike. Darwin mostly (but not always) used the symbol '&' in place of the word "and". He used the abbreviation "V" to mean vide or 'see', and "do." to mean ditto, or 'the same'. He also used the symbol "∠" in place of the written word 'angle', such that ∠^r means 'angular' and rt ∠s means 'right angles'. He often abbreviated the words "crystal" to "Cryst", "feldspar" to "feld", and "grey" to "gry". He used the unlikely word "smally" three times in this manuscript, and in his catalogue of geological specimens.⁵

Editorial comments are noted in red, within red square brackets ([ ]). Page numbers are also indicated in red and the words recto and verso are used to indicate the front and back of a page. Darwin did not number the verso pages. Words and letters that are illegible or uncertain are marked in italicized square brackets ([ ]). Marginal notes are defined by angular brackets (< >) and insertions are indicated with double angular brackets (<< >>). Annotations by the authors are added as footnotes. Global Positioning System (GPS) readings taken from Google Earth are provided for some of the places and formations that Darwin described. It should be noted that GPS readings of these same sites were measured in the field in 1996 and published by the authors in 2000.⁶ However, due to the US government's deployment of "selective availability" for all non-military GPS users prior to 2000 (which resulted in purposeful random errors of up to 100 meters), these published readings must be considered lower in resolution than the Google Earth values. The authors have since been re-measuring the location of sites in the field with a new GPS receiver (WGS-84 datum) and are listing and updating these more accurate readings on their website http://www.galapagosconnection.net/

Darwin's step by step experiences in Galápagos are explored in detail in the authors' book Darwin in Galápagos: Footsteps to a New World.⁷ An abbreviated sketch of Darwin's movements in the archipelago is provided below. Spanish place names are those in use today. Corresponding English names are provided in brackets.

A Synopsis of Darwin's Galápagos itinerary

The Beagle sailed into Galápagos waters on 15 September 1835. At 4 pm on 16 September Darwin and Captain FitzRoy landed for an hour at a place now called Cerro Tijeretas (Frigatebird Hill) on Isla San Cristóbal (Chatham Island). The following morning Darwin landed in Bahía Stephens (Stephens Bay). On 18 September the Beagle sailed up the coast to Bahía Agua de Tortuga Negra (Terrapin Road) and in the afternoon Darwin hiked inland to a tuff cone, now called Pan de Azucar (Sugar Loaf). The 19^th and 20^th were spent rounding the island and stopping at La Honda (Freshwater Bay) to determine the feasibility of collecting drinking water for the ship. There is no indication that Darwin went ashore here. On 21 September Darwin and his servant Syms Covington landed on the edge of a lava flow which Darwin named the Craterized District. They spent the 21^st and 22^nd exploring this flow, spending the night of the 21^st camped on a small beach. Darwin also explored a nearby tuff cone, Cerro Brujo (Finger Hill), a little further to the south. The Beagle sailed from San Cristóbal (Chatham) on the 23^rd. On the 24^th of September the Beagle anchored in Bahía Correo (Post Office Bay), Isla Floreana (Charles Island) and received a visit from the acting governor of the island, Nicholas Lawson. The next day Darwin and FitzRoy were taken by boat to Rada Black Beach (Black Beach), from where they hiked to a small settlement in the highlands. September 26 was spent at Post Office Bay. On 27 September Darwin climbed Cerro Pajas (Round Hill) to the summit of Floreana. The Beagle left Isla Floreana (Charles) on 28 September on route for Isla Isabela (Albemarle Island). After passing close by Isla Tortuga (Brattle Island), and stopping briefly at Caleta Iguana (Iguana Cove), the Beagle arrived at Caleta Tagus (Tagus Cove/Banks Cove) on the evening of 30 September. Darwin spent 1 October exploring a large tuff ring now called Cráter Beagle (Beagle Crater), and Tagus Cove. The Beagle left Isla Isabela (Albemarle) on 2 October, and after navigating past Islas Pinta (Abingdon Island), Genovesa (Tower Island) and Marchena (Bindloe Island) arrived at Isla Santiago (James Island) on 8 October. Darwin landed at Caleta Bucanero (Buccaneer Cove) with his servant Syms Covington, the ship's surgeon Benjamin Bynoe, and FitzRoy's steward Harry Fuller. These men remained camped on the island from 8-17 October while Captain FitzRoy took the Beagle back to Isla San Cristóbal (Chatham Island) to collect drinking water for the ship. During his ten days on shore Darwin made several excursions along the coast and into the highlands. After the men were picked up on 17 October the Beagle headed north towards Islas Wolf (Wenman Island) and Darwin (Culpepper Island) before leaving the archipelago on 20 October.

Darwin's Geological Specimens from Galápagos

Darwin's geological and paleontological collection from Galápagos consisted of forty rock specimens and three "fossil" marine shells: thirteen rocks and one rock with embedded uplifted marine shells from Isla San Cristóbal (Chatham Island), one "fossil" murex from Champion Island (more likely Enderby Island), four rocks from Isla Isabela (Albemarle Island), nineteen rocks from Isla Santiago (James Island), one rock and one collection of "fossil" marine shells from Isla Marchena (Bindloe Island), one rock from Isla Genovesa (Tower Island) and two rocks from Isla Pinta (Abingdon Island). The specimen numbers, collection location and date of collection are listed below. The tuff specimens are distinguished from other rocks.

Darwin's specimens.

Isla San Cristóbal (Chatham Island)
16 September 1835
3239 basalt. Cerro Tijeretas (Frigatebird Hill)
3290 uplifted shells. Cerro Tijeretas (Frigatebird Hill)

18 September 1835
3220 Tuff. Pan de Azucar (Sugar Loaf). Lower outer slopes of crater.
3221 Tuff. Pan de Azucar (Sugar Loaf). Lower outer slopes of crater.
3222 Tuff. Pan de Azucar (Sugar Loaf). Lower outer slopes of crater.
3223 Tuff. Pan de Azucar (Sugar Loaf). Upper outer slopes of crater.
3224 Tuff. Pan de Azucar (Sugar Loaf). Upper outer slopes of crater.
3225 Tuff. Pan de Azucar (Sugar Loaf). Central part of crater.

21-22 September 1835
3226 Tuff. Cerro Brujo (Finger Hill).
3238 Tuff. Cerro Brujo (Finger Hill).
3234 Craterized District.
3235 Interior of Cerro Brujo (Finger Hill).
3236 Tuff. Dyke of Cerro Brujo (Finger Hill).
3237 Tuff. Dyke of Cerro Brujo (Finger Hill).

Isla Floreana (Charles Island)
25-27 September 1835
3291 "Fossil" murex from "Champion" (more likely Enderby Island)

Isla Isabela (Albemarle Island)
1 October 1835
3247 Lava flow between Tagus and Beagle Craters.
3248 Lava flow between Tagus and Beagle Craters.
3249 Tuff. Beagle Crater.
3250 Tuff with accretionary lapilli. Beagle Crater.

Isla Santiago (James Island)
For a detailed description of the specimens collected from Santiago see: Herbert, S., Gibson, S., Norman, D., Geist, D., Estes, G., Grant, T. and Miles, A. 2009. Into the Field Again: Re-examining Charles Darwin's 1825 Geological Work on Isla Santiago (James Island) in the Galápagos Archipelago. Earth Sciences History 28(1): 1-31.

9 October 1835
These specimens collected in a SE line from behind Caleta Bucanero (Buccaneer Cove) to the island summit at Jaboncillos.
3265
3266
3267
3268

10 October 1835
These specimens collected from Caleta Bucanero (Buccaneer Cove)
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279

11 October 1835
3280. James Bay lava flow.
3281 James Bay lava flow.
3282. Tuff. Upper strata of Mina de Sal (Salt mine crater).
3283 Tuff. Upper strata of Mina de Sal (Salt mine crater).

Edward Main Chaffers' specimens

Isla Marchena (Bindloe Island)
Between 9-19 October 1835. Probably around 10 October.
3286
3292 Marine shells from tuff. Eastern side of island.

Isla Genovesa (Tower Island)
Between 9-19 October 1835. Probably around 14 October.
3287 North side of island.

Isla Abingdon (Pinta Island)
Between 9-19 October 1835. Probably around 17 October.
3288
3289

Darwin, C. R. Geological diary: Galapagos. (10.1835) Text & image CUL-DAR37.716-795A