M
MACNEIL, F. STEARNS (1909–1983)
David Hopley
James Cook University, Townsville, QLD, Australia
Darwin’s 1842 model for atoll development provoked
numerous alternative ideas including antecedent platforms, eustatic sea level oscillations, and integrated
hypotheses. Japanese researchers were the first to consider
that modern reefs are growing on limestone platforms
exposed to sub-aerial weathering during lower sea level
periods of the Pleistocene (Asano, 1942; Yabe, 1942;
Tayama, 1952). Their papers, however, were largely
ignored or dismissed (e.g., Umbgrove, 1947) until the ideas
were redeveloped in the American literature. Initially
Stearns (1946) believed that variations in sea level were
major factors in producing the relief of atolls and in particular, internal unconformities where the reef limestone was
eroded or exposed during low sea levels.
However, the paper published in 1954 by F. Stearns
MacNeil of the US Geological Survey has become the
most widely quoted source of the hypothesis of an inheritance from sub-aerial forms for the shape of atolls. Interestingly, MacNeil notes that Hoffmeister and Ladd
(1944) had previously concluded that the saucer shape of
many uplifted Pacific limestone islands was due to solution, and not to the fact that they were raised atolls, yet
they did not develop the argument in their exposition on
antecedent platforms. MacNeil’s theory recognized the
importance of organic growth during periods of submergence but placed at least equal importance on the role of
solution in fashioning the lagoonal depressions and anular
rims of atolls. Case-hardening and development of underground drainage systems were seen as important factors in
the development of the sub-aerially exposed limestone
surface. MacNeil, in the introduction to his 1954 paper,
stated:
Though it is true that most authors have sought to explain
barriers and atolls as the ultimate forms of reefs, the inclusion of all reef hypotheses under one heading implies more
conflict than really exists. Generally no distinction is made
between theories dealing mainly with the foundation of
reefs, and the shape of reefs. There is a general feeling
among investigators at present that atolls are not always
formed the same way, and therefore no one theory can
explain atolls.
and later:
It would seem that each atoll should be studied as an individual and it is not thought that the present hypothesis, believed
to be true for the oceanic atolls of the mid Pacific, is necessarily true for the atolls (sic) of the Great Barrier Reef.
MacNeil, 1954. pp. 402–403
It is possible here that MacNeil was too conservative in his
application of his hypothesis, for Purdy (1974) has greatly
extended the antecedent karst model to explain the configuration of all reefs by means of preferential reef accretion
on topographic highs in underlying subaerially weathered
surfaces. However, MacNeil’s statements implying that
the coral reef problem has been largely a matter of confusing structure and surface morphology, and of assuming
that all reefs have a similar evolution, are an illumination
of the problem not previously considered. It is from about
the time of his paper that general models of reef evolution
have become unfashionable, a trend that is noticeable
within geomorphology generally, as indicated by Higgins
(1975). Higgins attributes this decline in landscape
models to a change in the intellectual climate resulting
from increasing quantification and interest in process,
which in turn have suggested that complex landforms
may be explained by more than one hypothesis.
David Hopley (ed.), Encyclopedia of Modern Coral Reefs, DOI 10.1007/978-90-481-2639-2,
# Springer Science+Business Media B.V. 2011
MACNEIL, F. STEARNS (1909–1983)
David Hopley
James Cook University, Townsville, QLD, Australia
Darwin’s 1842 model for atoll development provoked
numerous alternative ideas including antecedent platforms, eustatic sea level oscillations, and integrated
hypotheses. Japanese researchers were the first to consider
that modern reefs are growing on limestone platforms
exposed to sub-aerial weathering during lower sea level
periods of the Pleistocene (Asano, 1942; Yabe, 1942;
Tayama, 1952). Their papers, however, were largely
ignored or dismissed (e.g., Umbgrove, 1947) until the ideas
were redeveloped in the American literature. Initially
Stearns (1946) believed that variations in sea level were
major factors in producing the relief of atolls and in particular, internal unconformities where the reef limestone was
eroded or exposed during low sea levels.
However, the paper published in 1954 by F. Stearns
MacNeil of the US Geological Survey has become the
most widely quoted source of the hypothesis of an inheritance from sub-aerial forms for the shape of atolls. Interestingly, MacNeil notes that Hoffmeister and Ladd
(1944) had previously concluded that the saucer shape of
many uplifted Pacific limestone islands was due to solution, and not to the fact that they were raised atolls, yet
they did not develop the argument in their exposition on
antecedent platforms. MacNeil’s theory recognized the
importance of organic growth during periods of submergence but placed at least equal importance on the role of
solution in fashioning the lagoonal depressions and anular
rims of atolls. Case-hardening and development of underground drainage systems were seen as important factors in
the development of the sub-aerially exposed limestone
surface. MacNeil, in the introduction to his 1954 paper,
stated:
Though it is true that most authors have sought to explain
barriers and atolls as the ultimate forms of reefs, the inclusion of all reef hypotheses under one heading implies more
conflict than really exists. Generally no distinction is made
between theories dealing mainly with the foundation of
reefs, and the shape of reefs. There is a general feeling
among investigators at present that atolls are not always
formed the same way, and therefore no one theory can
explain atolls.
and later:
It would seem that each atoll should be studied as an individual and it is not thought that the present hypothesis, believed
to be true for the oceanic atolls of the mid Pacific, is necessarily true for the atolls (sic) of the Great Barrier Reef.
MacNeil, 1954. pp. 402–403
It is possible here that MacNeil was too conservative in his
application of his hypothesis, for Purdy (1974) has greatly
extended the antecedent karst model to explain the configuration of all reefs by means of preferential reef accretion
on topographic highs in underlying subaerially weathered
surfaces. However, MacNeil’s statements implying that
the coral reef problem has been largely a matter of confusing structure and surface morphology, and of assuming
that all reefs have a similar evolution, are an illumination
of the problem not previously considered. It is from about
the time of his paper that general models of reef evolution
have become unfashionable, a trend that is noticeable
within geomorphology generally, as indicated by Higgins
(1975). Higgins attributes this decline in landscape
models to a change in the intellectual climate resulting
from increasing quantification and interest in process,
which in turn have suggested that complex landforms
may be explained by more than one hypothesis.
David Hopley (ed.), Encyclopedia of Modern Coral Reefs, DOI 10.1007/978-90-481-2639-2,
# Springer Science+Business Media B.V. 2011