Voyage of the Beagle and Darwin’s coral reef
theory
Darwin’s theory on coral reefs originally formed during
the famous voyage of the Beagle (1831–1836), with
Robert Fitzroy as Captain/Commander and Surveyor
(Fitzroy, 1839). Fitzroy received his “instructions” for the
voyage from the “Lords Commissioners of the Admiralty”:
“You are hereby required and directed to put to sea, in the
vessel you command, so soon as she shall be in every respect
ready, and to proceed in her, with all convenient expedition,
successively to Madeira or Teneriffe; the Cape de Verde
Islands; Fernando Noronha; and the South American station;
to perform the operations, and execute the surveys, pointed
out in the accompanying memorandum, which has been
drawn up under our direction by the Hydrographer of this
office; observing and following, in the prosecution of the said
surveys, and in your other operations, the directions and suggestions contained in the said memorandum.” (Extract from
“Instructions” in Fitzroy, 1839, p. 22).
As pointed out by Chancellor (2008 np), coral reefs
“. . .were in fact one of the key scientific objectives of the
Beagle’s orders from the Admiralty.” Certainly, the undertaking of coral reef investigations on the voyage were detailed
in the “memorandum” accompanying the instructions:
The circularly-formed Coral Islands in the Pacific occasionally afford excellent land-locked harbours, with a sufficient
entrance, and would be well adapted to any nice astronomical
observations. . . While these are quietly proceeding. . ., a very
interesting inquiry might be instituted respecting the formation of these coral reefs.
An exact geological map of the whole island should be
constructed, showing its form, the greatest height to which
the solid coral has risen, as well as that to which the fragments appear to have been forced. The slope of its sides
should be carefully measured in different places, and particularly on the external face, by a series of soundings, at very
short distances from each other, and carried out to the greatest
possible depths, at times when no tide or current can affect
the perpendicularity of the line. A modern and very plausible
theory has been put forward, that these wonderful formations, instead of ascending from the bottom of the sea, have
been raised from the summits of extinct volcanoes; and therefore the nature of the bottom at each of these soundings
should be noted, and every means exerted that ingenuity
can devise of discovering at what depth the coral formation
begins, and of what materials the substratum on which it rests
is composed. The shape, slope, and elevation of the coral
knolls in the lagoon would also help the investigation; and
no circumstances should be neglected which can render an
account of the general structure clear and perspicuous.
(Extract from “memorandum” in Fitzroy, 1839, p. 38).
Charles Darwin’s presence on the Beagle’s voyage
was precipitated by Fitzroy’s anxiousness “. . . that no
opportunity of collecting useful information, during the
voyage, should be lost. . .” so Fitzroy “. . . proposed to
the Hydrographer that some well-educated and scientific
person should be sought . . . . . . Captain Beaufort approved of the suggestion, and wrote to Professor Peacock,
of Cambridge, who consulted with a friend, Professor
Henslow, and he named Mr. Charles Darwin, grandson
of Dr. Darwin the poet, as a young man of promising ability, extremely fond of geology, and indeed all branches of
natural history.” (Fitzroy, 1839, pp. 18–19). In Fitzroy’s
(1839) list of persons aboard the Beagle when it sailed
from England, Darwin was listed as “naturalist.”
During the voyage of the Beagle, Darwin visited South
America in 1934–1935. He was strongly influenced
by Lyell’s Principles of Geology published in 1832 in
which Lyell dedicated the final chapter to coral reefs.
(see Chapter Lyell, Charles (1797–1875)). Influenced by
Lyell’s work, Darwin noted the effects of intermittent
uplift on the land together with erosion and deposition of
sediments. From this, he speculated on the effects of subsidence upon the upward growth of corals and made some
outstanding deductions before he had ever seen a coral
reef. He deduced that progressive island subsidence could
transform a fringing reef into a barrier reef and finally into
an atoll. According to Harvey (1982, p. 3) Darwin’s
deductive model was confirmed when he visited Tahiti
in November 1835 and viewed the island of Moorea from
the neighboring slopes behind Papeete. He saw the central
volcanic island surrounded by a lagoon, which in turn was
encircled by a barrier reef. He deduced that with progressive subsidence of the central volcanic island the
encircling reef would slowly grow upwards until the central lagoon had disappeared altogether leaving only
a circular rim of coral with a central lagoon. Thus, the theoretical development of fringing reefs to barrier reefs and
finally to atolls overcame the problem of explaining the
anomalously great depths at which shallow water reefal
limestones had been found.
The same sequence of reef development was not readily
applicable to continental margin reefs such as the Great
Barrier Reef (GBR). Harvey (1982) notes that Darwin
never visited the GBR although following the visit to
Tahiti, the Beagle on her homeward journey sailed around
the southern shores of Australia. Darwin did, however,
attempt to relate his subsidence theory to the GBR, suggesting that it “may have been important in the Reef’s evolution. Although he was not able to test this hypothesis,
the importance of his subsidence theory deduced from
Pacific atolls and the debate that followed its publication
had a profound effect upon research in the Great Barrier
Reef Province” (Harvey, 1982, p. 3).
A deductive theory
As noted by Chancellor and van Wyhe (2008) and Harvey
(1982), Darwin’s ideas on coral reefs had been formed
before he had seen one. Chancellor and van Wyhe (2008)
comment that Darwin’s “Santiago Notebook” “. . .has
been quoted from by many scholars in connection with
the famous passage which confirms that Darwin had
thought out his coral reef theory before seeing a coral
island, as he claimed in his Autobiography. . .”. In the
autobiography, Darwin wrote:
No other work of mine was begun in so deductive a spirit as
this; for the whole theory was thought out on the west coast of
300
DARWIN, CHARLES (1809–1882)
theory
Darwin’s theory on coral reefs originally formed during
the famous voyage of the Beagle (1831–1836), with
Robert Fitzroy as Captain/Commander and Surveyor
(Fitzroy, 1839). Fitzroy received his “instructions” for the
voyage from the “Lords Commissioners of the Admiralty”:
“You are hereby required and directed to put to sea, in the
vessel you command, so soon as she shall be in every respect
ready, and to proceed in her, with all convenient expedition,
successively to Madeira or Teneriffe; the Cape de Verde
Islands; Fernando Noronha; and the South American station;
to perform the operations, and execute the surveys, pointed
out in the accompanying memorandum, which has been
drawn up under our direction by the Hydrographer of this
office; observing and following, in the prosecution of the said
surveys, and in your other operations, the directions and suggestions contained in the said memorandum.” (Extract from
“Instructions” in Fitzroy, 1839, p. 22).
As pointed out by Chancellor (2008 np), coral reefs
“. . .were in fact one of the key scientific objectives of the
Beagle’s orders from the Admiralty.” Certainly, the undertaking of coral reef investigations on the voyage were detailed
in the “memorandum” accompanying the instructions:
The circularly-formed Coral Islands in the Pacific occasionally afford excellent land-locked harbours, with a sufficient
entrance, and would be well adapted to any nice astronomical
observations. . . While these are quietly proceeding. . ., a very
interesting inquiry might be instituted respecting the formation of these coral reefs.
An exact geological map of the whole island should be
constructed, showing its form, the greatest height to which
the solid coral has risen, as well as that to which the fragments appear to have been forced. The slope of its sides
should be carefully measured in different places, and particularly on the external face, by a series of soundings, at very
short distances from each other, and carried out to the greatest
possible depths, at times when no tide or current can affect
the perpendicularity of the line. A modern and very plausible
theory has been put forward, that these wonderful formations, instead of ascending from the bottom of the sea, have
been raised from the summits of extinct volcanoes; and therefore the nature of the bottom at each of these soundings
should be noted, and every means exerted that ingenuity
can devise of discovering at what depth the coral formation
begins, and of what materials the substratum on which it rests
is composed. The shape, slope, and elevation of the coral
knolls in the lagoon would also help the investigation; and
no circumstances should be neglected which can render an
account of the general structure clear and perspicuous.
(Extract from “memorandum” in Fitzroy, 1839, p. 38).
Charles Darwin’s presence on the Beagle’s voyage
was precipitated by Fitzroy’s anxiousness “. . . that no
opportunity of collecting useful information, during the
voyage, should be lost. . .” so Fitzroy “. . . proposed to
the Hydrographer that some well-educated and scientific
person should be sought . . . . . . Captain Beaufort approved of the suggestion, and wrote to Professor Peacock,
of Cambridge, who consulted with a friend, Professor
Henslow, and he named Mr. Charles Darwin, grandson
of Dr. Darwin the poet, as a young man of promising ability, extremely fond of geology, and indeed all branches of
natural history.” (Fitzroy, 1839, pp. 18–19). In Fitzroy’s
(1839) list of persons aboard the Beagle when it sailed
from England, Darwin was listed as “naturalist.”
During the voyage of the Beagle, Darwin visited South
America in 1934–1935. He was strongly influenced
by Lyell’s Principles of Geology published in 1832 in
which Lyell dedicated the final chapter to coral reefs.
(see Chapter Lyell, Charles (1797–1875)). Influenced by
Lyell’s work, Darwin noted the effects of intermittent
uplift on the land together with erosion and deposition of
sediments. From this, he speculated on the effects of subsidence upon the upward growth of corals and made some
outstanding deductions before he had ever seen a coral
reef. He deduced that progressive island subsidence could
transform a fringing reef into a barrier reef and finally into
an atoll. According to Harvey (1982, p. 3) Darwin’s
deductive model was confirmed when he visited Tahiti
in November 1835 and viewed the island of Moorea from
the neighboring slopes behind Papeete. He saw the central
volcanic island surrounded by a lagoon, which in turn was
encircled by a barrier reef. He deduced that with progressive subsidence of the central volcanic island the
encircling reef would slowly grow upwards until the central lagoon had disappeared altogether leaving only
a circular rim of coral with a central lagoon. Thus, the theoretical development of fringing reefs to barrier reefs and
finally to atolls overcame the problem of explaining the
anomalously great depths at which shallow water reefal
limestones had been found.
The same sequence of reef development was not readily
applicable to continental margin reefs such as the Great
Barrier Reef (GBR). Harvey (1982) notes that Darwin
never visited the GBR although following the visit to
Tahiti, the Beagle on her homeward journey sailed around
the southern shores of Australia. Darwin did, however,
attempt to relate his subsidence theory to the GBR, suggesting that it “may have been important in the Reef’s evolution. Although he was not able to test this hypothesis,
the importance of his subsidence theory deduced from
Pacific atolls and the debate that followed its publication
had a profound effect upon research in the Great Barrier
Reef Province” (Harvey, 1982, p. 3).
A deductive theory
As noted by Chancellor and van Wyhe (2008) and Harvey
(1982), Darwin’s ideas on coral reefs had been formed
before he had seen one. Chancellor and van Wyhe (2008)
comment that Darwin’s “Santiago Notebook” “. . .has
been quoted from by many scholars in connection with
the famous passage which confirms that Darwin had
thought out his coral reef theory before seeing a coral
island, as he claimed in his Autobiography. . .”. In the
autobiography, Darwin wrote:
No other work of mine was begun in so deductive a spirit as
this; for the whole theory was thought out on the west coast of
300
DARWIN, CHARLES (1809–1882)