Morris tribune. [volume] (Morris, Minn.) 1880-2000, 1912-08-16
ISLANDS OF CORAL
True Ones Only In the Pacific
and Indian Oceans.
THE GREAT BARRIER ATOLL.
This Famous Coral Reef, off the Aus
traIian Coast, Is the Largest In the
World and Extends For Thousands
Of MiIes-Bermuda's Worm Tubes.


World and Extends For Thousands
Of MiIes-Bermuda's Worm Tubes.
There are no true coral islands in the
Atlantic. The coral islands Of the Pa
cific and Indian oceans are very dis
tinct from the so called coral islands
of Bermuda and the West Indies.
True coral islands, or atolls, are
formed by corals building upward on
a submerged reef or peak until the
growth reaches the surface of the sea
or so near it that broken pieces OF coral,
drift, sand, etc., accumulate and IN
time build an exposed islet. At other
times the coral reef is raised above the
water by volcanic action. The Pacific
reefs are often circular or semicircular
In form, and such reefs are known as
atolls
The largest coral reef is the Great
Barrier reef of Australia, which ex-
tends for several thousand miles
The coral islands of the Atlantic are
formed by wave broken shells and bits
of coral which have become sol1dlt1ed
and fossilized by chemical action and
age. This material is known as AGO.
liam limestone and after exposure to
the air is exceedingly hard and dura-
BILE, but where freshly broken or cut
1t is very soft and can be chiseled and
sawed into blocks for building pur-
poses.
Many of the West Indian coral is
lands are partly composed of fossil
coral reefs which have been raised fal
above the present sea level by the vol
canic uplift of the rocks to which they
were attached. Such coral reefs, says
the American Boy, are often founC
hundreds of feet above sea level anC
In places are found alternating will
layers Of lava, showing that the is
lands have been raised and submerged
several times in the past.
The atoll-like reefs in Bermuda ar
not coral at all, but are formed Of in
Vulnerable worm tubes belonging t.
certain annelids. These worm tube
are often thickly incrusted with othe
growths, such as coraline, seaweeds
bryozoa, corals, etc., and thus have tn
appearance Of being composed of rea
coral.
Corals, when alive, are not white, bu
are of many beautiful and vivid shade
of green, pink, red, brown, yellow, Law
ender or orange.
A mass of living corals, when see
Of the tropical sea, is very beautifU
and brilliantly colored sight. Their
are a great many kinds Of coral. Som
are rounded and massive and ar
known as brain corals." Others ar
broad and spreading or branched, Will
others are delicately formed and yer
brittle. Others are covered with ros
shaped or star shaped markings an
are called rose" or "star corals."
The openings or indentatiOns in an
coral mark the spot where coral an
NAL lived. The animals or ''polyps
are very similar to sea anemones
form and have numerous feshy tent;
cles, which may be drawn in out {
sight when danger threatens. The Ell
tire coral is covered with animal ma
ter when alive, and it is only after a
the flesh is removed and the skeleto
is bleached that the white coral al
pears. All the corals mentioned al
known as "stony corals."
Another very large group of corals
the ''horny corals," or Gorgonias. TT
well known "sea FANS" as we'll as til
''red coraP' used for jewelry, belong I
this group.