Mayor collected specimens for the MCZ in various
locations on the east coast of America and around the
Dry Tortugas, in the Gulf of Mexico. Between 1896 and
1900, he also accompanied Agassiz on three major
collecting expeditions in the South Pacific Ocean. Mayor
received the Ph.D. degree in 1896, but continued in his
position at the MCZ until 1900, when he left to become
curator of zoology in the Brooklyn Museum.
In 1903, the Carnegie Institution of Washington (CIW)
approved Mayor’s proposal for establishing a tropical
marine laboratory on Loggerhead Key, in the Dry
Tortugas, and made him director of the new station, which
opened in 1904. During the early years of the Laboratory,
Mayor worked mainly on jellyfish taxonomy, and, in
1910, completed the monumental three-volume work
titled Medusae of the World. Two years later, he published
Ctenophores of the Atlantic Coast of North Atlantic,
a standard work on the comb jellies.
Influenced by the studies of the prodigious coral geologist
Thomas Wayland Vaughan, who conducted considerable
research at the Tortugas Laboratory, Mayor began around
1913 to focus his attention on the stony corals. In the waters
of the Florida Keys and later those of the South Pacific,
Mayor concentrated on the ecology of coral reefs, and produced a number of pioneering studies on the growth-rate of
corals and the effects of temperature, light, water depth, wave
action, fresh water, and silt on coral development. In 1917, he
began to use a diving helmet to further his studies, thus
becoming one of the first biologists to conduct underwater
explorations of reefs. Mayor was elected to membership in
the National Academy of Sciences in 1916.
By the time of his premature death on 24 June 1922, on
Loggerhead Key, Mayor had achieved international
acclaim for his pioneering work in jellyfish and comb jelly
taxonomy and on coral-reef ecology. A monument in his
memory was erected on Loggerhead Key in 1923.
Bibliography
Stephens, L. D., and Calder, D. R., 2006. Seafaring Scientist: Alfred
Goldsborough Mayor, Pioneer in Marine Biology. Columbia:
University of South Carolina Press.
Cross-references
Agassiz, Alexander (1835–1910),
Vaughan, Thomas Wayland (1870–1952)
MEGABLOCKS
Cliff Frohlich, Matthew J. Hornbach,
Frederick W. Taylor
John A. and Katherine G. Jackson School of Geosciences,
University of Texas, Austin, TX, USA
Synonyms
Boulder or megaboulder deposits; Coral boulders; Coral
megablocks; Erratic coral boulders
Definition
Megablocks. Intact blocks or boulders, often composed of
coral and occasionally with dimensions of 10 m or greater,
situated well apart from (as much as 100–500 m) and
sometimes well above (up to 30 m) their original formation sites.
Introduction
Coral megablocks are large erratic boulders detached from
the reefs or paleoreefs where they formed, and presently
situated in the surf zone, along the beach, or still further
inland. We distinguish megablocks from sea stacks, which
are coral formations that may be similar in size and location to megablocks but are still in growth position,
attached at their bases. Megablocks as discussed here are
also distinct from tectonic segments or arc segments, often
described along subduction zones, which are tectonic
blocks with horizontal dimensions up to tens of km or
greater that undergo coherent lateral or vertical motions
distinct from the motions of adjacent blocks or segments.
There is also a vast literature describing ice-rafted or glacier-deposited boulders composed of materials other than
coral; for example, glacier-transported boulders reported
in Tierra del Fuego by Charles Darwin (1842) are still
being studied today (Kaplan et al., 2007).
Scientific interest in megablocks, whether composed of
coral or otherwise, often focuses on determining the mechanism and timing of their emplacement. Where coral
megablocks may have been emplaced by prehistoric
storms or tsunami waves, analysis can provide information about potential hazards from natural events too rare
to be represented in the historical record.
Examples
Erratic megablocks often occur near and below sea cliffs.
Although the specific mechanism of transport may be
uncertain, in most cases a plausible explanation is that
the blocks separated from the cliff due to the action of surf,
biological activity, earthquakes, or weathering, and subsequently were transported downhill via mass wasting.
However, coral megablocks also occur where sea cliffs
are absent, and may lie well above their original sites of
formation (Scheffers and Kelletat, 2003). To emplace
these, storm or tsunami waves are the most credible mechanism (e.g., Zhao et al., 2009), especially as some such
emplacements have occurred historically. The 26 December 2004 Indonesian tsunami deposited hundreds of
meter-sized coral boulders in the intertidal zone along
Pakarang Cape, Thailand (Goto et al., 2007), including
some with estimated weights up to 40 tons (Kelletat
et al., 2007). On 27 August 1883 the island of Krakatau
in Indonesia experienced a huge explosive eruption; at
Anyer beach at a distance of 40 km, this produced a tsunami
with a reported height of 36 m that moved coral megablocks
distances up to 240 m. The largest transported megablock
had a reported volume 317 m
3 and an estimated mass of
600 tons (see picture in Simkin and Fiske, 1983).
MEGABLOCKS
679
locations on the east coast of America and around the
Dry Tortugas, in the Gulf of Mexico. Between 1896 and
1900, he also accompanied Agassiz on three major
collecting expeditions in the South Pacific Ocean. Mayor
received the Ph.D. degree in 1896, but continued in his
position at the MCZ until 1900, when he left to become
curator of zoology in the Brooklyn Museum.
In 1903, the Carnegie Institution of Washington (CIW)
approved Mayor’s proposal for establishing a tropical
marine laboratory on Loggerhead Key, in the Dry
Tortugas, and made him director of the new station, which
opened in 1904. During the early years of the Laboratory,
Mayor worked mainly on jellyfish taxonomy, and, in
1910, completed the monumental three-volume work
titled Medusae of the World. Two years later, he published
Ctenophores of the Atlantic Coast of North Atlantic,
a standard work on the comb jellies.
Influenced by the studies of the prodigious coral geologist
Thomas Wayland Vaughan, who conducted considerable
research at the Tortugas Laboratory, Mayor began around
1913 to focus his attention on the stony corals. In the waters
of the Florida Keys and later those of the South Pacific,
Mayor concentrated on the ecology of coral reefs, and produced a number of pioneering studies on the growth-rate of
corals and the effects of temperature, light, water depth, wave
action, fresh water, and silt on coral development. In 1917, he
began to use a diving helmet to further his studies, thus
becoming one of the first biologists to conduct underwater
explorations of reefs. Mayor was elected to membership in
the National Academy of Sciences in 1916.
By the time of his premature death on 24 June 1922, on
Loggerhead Key, Mayor had achieved international
acclaim for his pioneering work in jellyfish and comb jelly
taxonomy and on coral-reef ecology. A monument in his
memory was erected on Loggerhead Key in 1923.
Bibliography
Stephens, L. D., and Calder, D. R., 2006. Seafaring Scientist: Alfred
Goldsborough Mayor, Pioneer in Marine Biology. Columbia:
University of South Carolina Press.
Cross-references
Agassiz, Alexander (1835–1910),
Vaughan, Thomas Wayland (1870–1952)
MEGABLOCKS
Cliff Frohlich, Matthew J. Hornbach,
Frederick W. Taylor
John A. and Katherine G. Jackson School of Geosciences,
University of Texas, Austin, TX, USA
Synonyms
Boulder or megaboulder deposits; Coral boulders; Coral
megablocks; Erratic coral boulders
Definition
Megablocks. Intact blocks or boulders, often composed of
coral and occasionally with dimensions of 10 m or greater,
situated well apart from (as much as 100–500 m) and
sometimes well above (up to 30 m) their original formation sites.
Introduction
Coral megablocks are large erratic boulders detached from
the reefs or paleoreefs where they formed, and presently
situated in the surf zone, along the beach, or still further
inland. We distinguish megablocks from sea stacks, which
are coral formations that may be similar in size and location to megablocks but are still in growth position,
attached at their bases. Megablocks as discussed here are
also distinct from tectonic segments or arc segments, often
described along subduction zones, which are tectonic
blocks with horizontal dimensions up to tens of km or
greater that undergo coherent lateral or vertical motions
distinct from the motions of adjacent blocks or segments.
There is also a vast literature describing ice-rafted or glacier-deposited boulders composed of materials other than
coral; for example, glacier-transported boulders reported
in Tierra del Fuego by Charles Darwin (1842) are still
being studied today (Kaplan et al., 2007).
Scientific interest in megablocks, whether composed of
coral or otherwise, often focuses on determining the mechanism and timing of their emplacement. Where coral
megablocks may have been emplaced by prehistoric
storms or tsunami waves, analysis can provide information about potential hazards from natural events too rare
to be represented in the historical record.
Examples
Erratic megablocks often occur near and below sea cliffs.
Although the specific mechanism of transport may be
uncertain, in most cases a plausible explanation is that
the blocks separated from the cliff due to the action of surf,
biological activity, earthquakes, or weathering, and subsequently were transported downhill via mass wasting.
However, coral megablocks also occur where sea cliffs
are absent, and may lie well above their original sites of
formation (Scheffers and Kelletat, 2003). To emplace
these, storm or tsunami waves are the most credible mechanism (e.g., Zhao et al., 2009), especially as some such
emplacements have occurred historically. The 26 December 2004 Indonesian tsunami deposited hundreds of
meter-sized coral boulders in the intertidal zone along
Pakarang Cape, Thailand (Goto et al., 2007), including
some with estimated weights up to 40 tons (Kelletat
et al., 2007). On 27 August 1883 the island of Krakatau
in Indonesia experienced a huge explosive eruption; at
Anyer beach at a distance of 40 km, this produced a tsunami
with a reported height of 36 m that moved coral megablocks
distances up to 240 m. The largest transported megablock
had a reported volume 317 m
3 and an estimated mass of
600 tons (see picture in Simkin and Fiske, 1983).
MEGABLOCKS
679