DANA, JAMES DWIGHT (1813–1895)
Tom Spencer
University of Cambridge, Cambridge, UK
James Dwight Dana (1813–1895) American geologist,
mineralogist, and naturalist. Holder of the Silliman Professorship of Natural History and Geology at Yale College,
1850–1892. Dana was geologist and mineralogist of the
United States Exploring Expedition commanded by
Charles Wilkes (1838–1842), gaining field experience of
volcanoes and coral reefs in Madeira, Kiribati, Tuvalu,
the Tuamotu Archipelago, the Society Islands, Samoa,
Tonga, Fiji, and the Phoenix and Hawaiian Islands.
His expedition reports, published in large volumes with
elaborate plates and an atlas, included Zoophytes (1846),
Geology (1849), and Crustacea (1852–1855). Dana was
the foremost American geologist of his time, writing more
than 200 books and published papers, and he held an influential position as editor of the American Journal of Science. His highly popular “On Coral Reefs and Islands”
published in 1853 (revised as “Corals and Coral Islands”
(1872, then 1890)), established coral reefs as a legitimate
object of scientific inquiry in North America. One of the
key elements in Dana’s writings was his strong support
for the Darwinian theory of coral reef development. He
tried to refine Darwin’s estimate of the area of the Pacific
Ocean characterized by subsidence (as evidenced in
Darwin’s (1842) maps of the distribution of barrier reefs
and atolls) and came to the remarkable conclusion, prefiguring modern plate tectonic theory, that subsidence
had increased across the Pacific Ocean basin from south
to north. He recognized the morphological evidence for
the sequence of island ages in the Hawaiian Islands and
was the first to argue for the paucity of reef development
on the eastern sides of the ocean basins as a result of
the presence of cool sea surface temperatures. As the “outstanding fluvialist” (Chorley et al., 1964, p. 367) of the
mid-nineteenth century, he recognized the fluvial dissection of mid-ocean volcanoes and the relation of valley
development and stream density to rainfall patterns on
windward and leeward volcanic slopes. His observation
that island subsidence would lead to an irregular coastline
with large embayments, as commonly seen on volcanic
islands lying within barrier reef lagoons, was a powerful
proof in favor of the subsidence theory, as recognized by
Charles Darwin himself.
Bibliography
Appleman, D. E., 1985. James Dwight Dana and Pacific geology. In
Viola, H. J., and Margolis, C. (eds.), Magnificent Voyagers: the
U.S. Exploring Expedition, 1838–1842. Washington DC:
Smithsonian Institution Press, pp. 89–118.
Chorley, R. J., Dunn, A. J., and Beckinsale, R. P., 1964. The History
of the Study of Landforms or the Development of Geomorphology. Volume 1. Geomorphology Before Davis. London:
Methuen.
Dana, J. D., 1843. On the temperature limiting the distribution of
coral reefs. American Journal of Science, 45, 130–131.
Dana, J. D., 1872. Corals and Coral Islands. New York: Dodd,
Mead & Co.
Darwin, C. R., 1842. The Structure and Distribution of Coral Reefs.
London: Smith Elder.
Gilman, D. C., 1899. The Life of James Dwight Dana. New York:
Harper & Brothers.
Natland, J. H., 1997. At vulcan’s shoulder: James Dwight Dana and
the beginnings of planetary volcanology. American Journal of
Science, 297, 312–342.
Cross-references
Darwin, Charles (1809–1882)
Davis, William Morris (1850–1934)
Subsidence Hypothesis of Reef Development
DARWIN POINT
Richard W. Grigg
University of Hawaii, Honolulu, HI, USA
Darwin Point
Darwin Points are drowning thresholds for coral reefs and
coral islands that have existed in the world oceans since
the evolution of reef building corals at the beginning of
the Mesozoic Era ~240 Ma (Grigg, in press). A Darwin
Point is reached when the net production or vertical accretion rate of CaCO 3 by reef building corals no longer keeps
pace with relative sea level. A Darwin Point is exceeded
when the reef structure permanently drowns. Drowning
occurs when production rates due to coral growth are
exceeded by rates of bio-erosion, physical-induced losses,
rates of island subsidence, or sea-level rise. During the
last transgression, the sea level rose on the order of
130 m (21,000 years B.P. to the present), and many coral
reefs in the world drowned. Another classic example
where a Darwin Point exists is the northwestern end of
the Hawaiian Archipelago (Grigg, 1982) (see Figure 2
in the entry Hawaiian Emperor Volcanic Chain and Coral
Reef History), beyond which atolls drown and become
guyots. Even older and deeper examples are the numerous
guyots that dot the northwestern Pacific Ocean that
today make up, in part, the Mid-Pacific Mountains
(Flood, 1999).
Clearly, there are many causal factors that potentially
produce “Darwin Point events,” and there is an abundant
literature on the question of why coral reefs fail (drown)
(Chave et al., 1972; Hopley, 1982; Grigg and Epp, 1989;
Grigg, 2006). In the modern day, perhaps the most common examples of Darwin Points are the vertical depth
limits of reef building corals set by light extinction or
a combination of factors including light extinction, bioerosion, temperature stratification, or sedimentation
(Figure 1). Looking at the future and to the possible effects
298
DANA, JAMES DWIGHT (1813–1895)
Tom Spencer
University of Cambridge, Cambridge, UK
James Dwight Dana (1813–1895) American geologist,
mineralogist, and naturalist. Holder of the Silliman Professorship of Natural History and Geology at Yale College,
1850–1892. Dana was geologist and mineralogist of the
United States Exploring Expedition commanded by
Charles Wilkes (1838–1842), gaining field experience of
volcanoes and coral reefs in Madeira, Kiribati, Tuvalu,
the Tuamotu Archipelago, the Society Islands, Samoa,
Tonga, Fiji, and the Phoenix and Hawaiian Islands.
His expedition reports, published in large volumes with
elaborate plates and an atlas, included Zoophytes (1846),
Geology (1849), and Crustacea (1852–1855). Dana was
the foremost American geologist of his time, writing more
than 200 books and published papers, and he held an influential position as editor of the American Journal of Science. His highly popular “On Coral Reefs and Islands”
published in 1853 (revised as “Corals and Coral Islands”
(1872, then 1890)), established coral reefs as a legitimate
object of scientific inquiry in North America. One of the
key elements in Dana’s writings was his strong support
for the Darwinian theory of coral reef development. He
tried to refine Darwin’s estimate of the area of the Pacific
Ocean characterized by subsidence (as evidenced in
Darwin’s (1842) maps of the distribution of barrier reefs
and atolls) and came to the remarkable conclusion, prefiguring modern plate tectonic theory, that subsidence
had increased across the Pacific Ocean basin from south
to north. He recognized the morphological evidence for
the sequence of island ages in the Hawaiian Islands and
was the first to argue for the paucity of reef development
on the eastern sides of the ocean basins as a result of
the presence of cool sea surface temperatures. As the “outstanding fluvialist” (Chorley et al., 1964, p. 367) of the
mid-nineteenth century, he recognized the fluvial dissection of mid-ocean volcanoes and the relation of valley
development and stream density to rainfall patterns on
windward and leeward volcanic slopes. His observation
that island subsidence would lead to an irregular coastline
with large embayments, as commonly seen on volcanic
islands lying within barrier reef lagoons, was a powerful
proof in favor of the subsidence theory, as recognized by
Charles Darwin himself.
Bibliography
Appleman, D. E., 1985. James Dwight Dana and Pacific geology. In
Viola, H. J., and Margolis, C. (eds.), Magnificent Voyagers: the
U.S. Exploring Expedition, 1838–1842. Washington DC:
Smithsonian Institution Press, pp. 89–118.
Chorley, R. J., Dunn, A. J., and Beckinsale, R. P., 1964. The History
of the Study of Landforms or the Development of Geomorphology. Volume 1. Geomorphology Before Davis. London:
Methuen.
Dana, J. D., 1843. On the temperature limiting the distribution of
coral reefs. American Journal of Science, 45, 130–131.
Dana, J. D., 1872. Corals and Coral Islands. New York: Dodd,
Mead & Co.
Darwin, C. R., 1842. The Structure and Distribution of Coral Reefs.
London: Smith Elder.
Gilman, D. C., 1899. The Life of James Dwight Dana. New York:
Harper & Brothers.
Natland, J. H., 1997. At vulcan’s shoulder: James Dwight Dana and
the beginnings of planetary volcanology. American Journal of
Science, 297, 312–342.
Cross-references
Darwin, Charles (1809–1882)
Davis, William Morris (1850–1934)
Subsidence Hypothesis of Reef Development
DARWIN POINT
Richard W. Grigg
University of Hawaii, Honolulu, HI, USA
Darwin Point
Darwin Points are drowning thresholds for coral reefs and
coral islands that have existed in the world oceans since
the evolution of reef building corals at the beginning of
the Mesozoic Era ~240 Ma (Grigg, in press). A Darwin
Point is reached when the net production or vertical accretion rate of CaCO 3 by reef building corals no longer keeps
pace with relative sea level. A Darwin Point is exceeded
when the reef structure permanently drowns. Drowning
occurs when production rates due to coral growth are
exceeded by rates of bio-erosion, physical-induced losses,
rates of island subsidence, or sea-level rise. During the
last transgression, the sea level rose on the order of
130 m (21,000 years B.P. to the present), and many coral
reefs in the world drowned. Another classic example
where a Darwin Point exists is the northwestern end of
the Hawaiian Archipelago (Grigg, 1982) (see Figure 2
in the entry Hawaiian Emperor Volcanic Chain and Coral
Reef History), beyond which atolls drown and become
guyots. Even older and deeper examples are the numerous
guyots that dot the northwestern Pacific Ocean that
today make up, in part, the Mid-Pacific Mountains
(Flood, 1999).
Clearly, there are many causal factors that potentially
produce “Darwin Point events,” and there is an abundant
literature on the question of why coral reefs fail (drown)
(Chave et al., 1972; Hopley, 1982; Grigg and Epp, 1989;
Grigg, 2006). In the modern day, perhaps the most common examples of Darwin Points are the vertical depth
limits of reef building corals set by light extinction or
a combination of factors including light extinction, bioerosion, temperature stratification, or sedimentation
(Figure 1). Looking at the future and to the possible effects
298
DANA, JAMES DWIGHT (1813–1895)